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Chapter 0. Preface
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0.1 About This Book
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Chapter 1. Introduction to Algorithms
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1.1 Algorithms are Everywhere
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1.2 What is an Algorithm
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Chapter 2. Complexity Analysis
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2.1 Algorithm Efficiency Assessment
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2.2 Iteration and Recursion
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2.3 Time Complexity
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2.4 Space Complexity
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2.5 Summary
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Chapter 3. Data Structures
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3.1 Classification of Data Structures
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3.2 Fundamental Data Types
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3.3 Number Encoding *
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3.4 Character Encoding *
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3.5 Summary
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Chapter 4. Array and Linked List
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Chapter 4. Array and Linked List
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4.1 Array
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4.2 Linked List
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4.3 List
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4.4 Memory and Cache
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4.5 Summary
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Chapter 5. Stack and Queue
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Chapter 5. Stack and Queue
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5.1 Stack
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5.2 Queue
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5.3 Double-ended Queue
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5.4 Summary
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Chapter 6. Hash Table
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Chapter 6. Hash Table
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6.1 Hash Table
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6.2 Hash Collision
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6.3 Hash Algorithm
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6.4 Summary
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Chapter 7. Tree
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Chapter 7. Tree
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7.1 Binary Tree
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7.2 Binary Tree Traversal
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7.2 Binary Tree Traversal
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Table of contents
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7.2.1 Level-order traversal
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1. Code implementation
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2. Complexity analysis
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7.2.2 Preorder, inorder, and postorder traversal
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1. Code implementation
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7.3 Array Representation of Tree
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7.4 Binary Search Tree
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7.5 AVL Tree *
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7.2.1 Level-order traversal
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7.2.2 Preorder, inorder, and postorder traversal
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< h1 id = "72-binary-tree-traversal" > 7.2 Binary tree traversal< a class = "headerlink" href = "#72-binary-tree-traversal" title = "Permanent link" > ¶ < / a > < / h1 >
< p > From the perspective of physical structure, a tree is a data structure based on linked lists, hence its traversal method involves accessing nodes one by one through pointers. However, a tree is a non-linear data structure, which makes traversing a tree more complex than traversing a linked list, requiring the assistance of search algorithms to achieve.< / p >
< p > Common traversal methods for binary trees include level-order traversal, preorder traversal, inorder traversal, and postorder traversal, among others.< / p >
< h2 id = "721-level-order-traversal" > 7.2.1 Level-order traversal< a class = "headerlink" href = "#721-level-order-traversal" title = "Permanent link" > ¶ < / a > < / h2 >
< p > As shown in the Figure 7-9 , "level-order traversal" traverses the binary tree from top to bottom, layer by layer, and accesses nodes in each layer in a left-to-right order.< / p >
< p > Level-order traversal essentially belongs to "breadth-first traversal", also known as "breadth-first search (BFS)", which embodies a "circumferentially outward expanding" layer-by-layer traversal method.< / p >
< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/binary_tree_bfs.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "Level-order traversal of a binary tree" class = "animation-figure" src = "../binary_tree_traversal.assets/binary_tree_bfs.png" / > < / a > < / p >
< p align = "center" > Figure 7-9 Level-order traversal of a binary tree < / p >
< h3 id = "1-code-implementation" > 1. Code implementation< a class = "headerlink" href = "#1-code-implementation" title = "Permanent link" > ¶ < / a > < / h3 >
< p > Breadth-first traversal is usually implemented with the help of a "queue". The queue follows the "first in, first out" rule, while breadth-first traversal follows the "layer-by-layer progression" rule, the underlying ideas of the two are consistent. The implementation code is as follows:< / p >
< div class = "tabbed-set tabbed-alternate" data-tabs = "1:14" > < input checked = "checked" id = "__tabbed_1_1" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_2" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_3" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_4" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_5" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_6" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_7" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_8" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_9" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_10" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_11" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_12" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_13" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_14" name = "__tabbed_1" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_1_1" > Python< / label > < label for = "__tabbed_1_2" > C++< / label > < label for = "__tabbed_1_3" > Java< / label > < label for = "__tabbed_1_4" > C#< / label > < label for = "__tabbed_1_5" > Go< / label > < label for = "__tabbed_1_6" > Swift< / label > < label for = "__tabbed_1_7" > JS< / label > < label for = "__tabbed_1_8" > TS< / label > < label for = "__tabbed_1_9" > Dart< / label > < label for = "__tabbed_1_10" > Rust< / label > < label for = "__tabbed_1_11" > C< / label > < label for = "__tabbed_1_12" > Kotlin< / label > < label for = "__tabbed_1_13" > Ruby< / label > < label for = "__tabbed_1_14" > Zig< / label > < / div >
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< div class = "highlight" > < span class = "filename" > binary_tree_bfs.py< / span > < pre > < span > < / span > < code > < a id = "__codelineno-0-1" name = "__codelineno-0-1" href = "#__codelineno-0-1" > < / a > < span class = "k" > def< / span > < span class = "nf" > level_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > )< / span > < span class = "o" > -> < / span > < span class = "nb" > list< / span > < span class = "p" > [< / span > < span class = "nb" > int< / span > < span class = "p" > ]:< / span >
< a id = "__codelineno-0-2" name = "__codelineno-0-2" href = "#__codelineno-0-2" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 层序遍历" " " < / span >
< a id = "__codelineno-0-3" name = "__codelineno-0-3" href = "#__codelineno-0-3" > < / a > < span class = "c1" > # 初始化队列，加入根节点< / span >
< a id = "__codelineno-0-4" name = "__codelineno-0-4" href = "#__codelineno-0-4" > < / a > < span class = "n" > queue< / span > < span class = "p" > :< / span > < span class = "n" > deque< / span > < span class = "p" > [< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ]< / span > < span class = "o" > =< / span > < span class = "n" > deque< / span > < span class = "p" > ()< / span >
< a id = "__codelineno-0-5" name = "__codelineno-0-5" href = "#__codelineno-0-5" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > )< / span >
< a id = "__codelineno-0-6" name = "__codelineno-0-6" href = "#__codelineno-0-6" > < / a > < span class = "c1" > # 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-0-7" name = "__codelineno-0-7" href = "#__codelineno-0-7" > < / a > < span class = "n" > res< / span > < span class = "o" > =< / span > < span class = "p" > []< / span >
< a id = "__codelineno-0-8" name = "__codelineno-0-8" href = "#__codelineno-0-8" > < / a > < span class = "k" > while< / span > < span class = "n" > queue< / span > < span class = "p" > :< / span >
< a id = "__codelineno-0-9" name = "__codelineno-0-9" href = "#__codelineno-0-9" > < / a > < span class = "n" > node< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > =< / span > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > popleft< / span > < span class = "p" > ()< / span > < span class = "c1" > # 队列出队< / span >
< a id = "__codelineno-0-10" name = "__codelineno-0-10" href = "#__codelineno-0-10" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span > < span class = "c1" > # 保存节点值< / span >
< a id = "__codelineno-0-11" name = "__codelineno-0-11" href = "#__codelineno-0-11" > < / a > < span class = "k" > if< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "ow" > is< / span > < span class = "ow" > not< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-0-12" name = "__codelineno-0-12" href = "#__codelineno-0-12" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span > < span class = "c1" > # 左子节点入队< / span >
< a id = "__codelineno-0-13" name = "__codelineno-0-13" href = "#__codelineno-0-13" > < / a > < span class = "k" > if< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "ow" > is< / span > < span class = "ow" > not< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-0-14" name = "__codelineno-0-14" href = "#__codelineno-0-14" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span > < span class = "c1" > # 右子节点入队< / span >
< a id = "__codelineno-0-15" name = "__codelineno-0-15" href = "#__codelineno-0-15" > < / a > < span class = "k" > return< / span > < span class = "n" > res< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.cpp< / span > < pre > < span > < / span > < code > < a id = "__codelineno-1-1" name = "__codelineno-1-1" href = "#__codelineno-1-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-1-2" name = "__codelineno-1-2" href = "#__codelineno-1-2" > < / a > < span class = "n" > vector< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-1-3" name = "__codelineno-1-3" href = "#__codelineno-1-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-1-4" name = "__codelineno-1-4" href = "#__codelineno-1-4" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *> < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-5" name = "__codelineno-1-5" href = "#__codelineno-1-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-1-6" name = "__codelineno-1-6" href = "#__codelineno-1-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-1-7" name = "__codelineno-1-7" href = "#__codelineno-1-7" > < / a > < span class = "w" > < / span > < span class = "n" > vector< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-8" name = "__codelineno-1-8" href = "#__codelineno-1-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > empty< / span > < span class = "p" > ())< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-1-9" name = "__codelineno-1-9" href = "#__codelineno-1-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > front< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-1-10" name = "__codelineno-1-10" href = "#__codelineno-1-10" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > pop< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-1-11" name = "__codelineno-1-11" href = "#__codelineno-1-11" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-1-12" name = "__codelineno-1-12" href = "#__codelineno-1-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-1-13" name = "__codelineno-1-13" href = "#__codelineno-1-13" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-1-14" name = "__codelineno-1-14" href = "#__codelineno-1-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-1-15" name = "__codelineno-1-15" href = "#__codelineno-1-15" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-1-16" name = "__codelineno-1-16" href = "#__codelineno-1-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-1-17" name = "__codelineno-1-17" href = "#__codelineno-1-17" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-18" name = "__codelineno-1-18" href = "#__codelineno-1-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.java< / span > < pre > < span > < / span > < code > < a id = "__codelineno-2-1" name = "__codelineno-2-1" href = "#__codelineno-2-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-2-2" name = "__codelineno-2-2" href = "#__codelineno-2-2" > < / a > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "n" > Integer< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-2-3" name = "__codelineno-2-3" href = "#__codelineno-2-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-2-4" name = "__codelineno-2-4" href = "#__codelineno-2-4" > < / a > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "w" > < / span > < span class = "n" > LinkedList< / span > < span class = "o" > < > < / span > < span class = "p" > ();< / span >
< a id = "__codelineno-2-5" name = "__codelineno-2-5" href = "#__codelineno-2-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-2-6" name = "__codelineno-2-6" href = "#__codelineno-2-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-2-7" name = "__codelineno-2-7" href = "#__codelineno-2-7" > < / a > < span class = "w" > < / span > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "n" > Integer< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "w" > < / span > < span class = "n" > ArrayList< / span > < span class = "o" > < > < / span > < span class = "p" > ();< / span >
< a id = "__codelineno-2-8" name = "__codelineno-2-8" href = "#__codelineno-2-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > isEmpty< / span > < span class = "p" > ())< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-2-9" name = "__codelineno-2-9" href = "#__codelineno-2-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > poll< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-2-10" name = "__codelineno-2-10" href = "#__codelineno-2-10" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-2-11" name = "__codelineno-2-11" href = "#__codelineno-2-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-2-12" name = "__codelineno-2-12" href = "#__codelineno-2-12" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-2-13" name = "__codelineno-2-13" href = "#__codelineno-2-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-2-14" name = "__codelineno-2-14" href = "#__codelineno-2-14" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-2-15" name = "__codelineno-2-15" href = "#__codelineno-2-15" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-2-16" name = "__codelineno-2-16" href = "#__codelineno-2-16" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-2-17" name = "__codelineno-2-17" href = "#__codelineno-2-17" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.cs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-3-1" name = "__codelineno-3-1" href = "#__codelineno-3-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-3-2" name = "__codelineno-3-2" href = "#__codelineno-3-2" > < / a > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > LevelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-3" name = "__codelineno-3-3" href = "#__codelineno-3-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-3-4" name = "__codelineno-3-4" href = "#__codelineno-3-4" > < / a > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-3-5" name = "__codelineno-3-5" href = "#__codelineno-3-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-3-6" name = "__codelineno-3-6" href = "#__codelineno-3-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-3-7" name = "__codelineno-3-7" href = "#__codelineno-3-7" > < / a > < span class = "w" > < / span > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-3-8" name = "__codelineno-3-8" href = "#__codelineno-3-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Count< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "m" > 0< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-9" name = "__codelineno-3-9" href = "#__codelineno-3-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Dequeue< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-3-10" name = "__codelineno-3-10" href = "#__codelineno-3-10" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "o" > !< / span > < span class = "p" > .< / span > < span class = "n" > Value< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-3-11" name = "__codelineno-3-11" href = "#__codelineno-3-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-12" name = "__codelineno-3-12" href = "#__codelineno-3-12" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-3-13" name = "__codelineno-3-13" href = "#__codelineno-3-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-14" name = "__codelineno-3-14" href = "#__codelineno-3-14" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-3-15" name = "__codelineno-3-15" href = "#__codelineno-3-15" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-3-16" name = "__codelineno-3-16" href = "#__codelineno-3-16" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-3-17" name = "__codelineno-3-17" href = "#__codelineno-3-17" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.go< / span > < pre > < span > < / span > < code > < a id = "__codelineno-4-1" name = "__codelineno-4-1" href = "#__codelineno-4-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-4-2" name = "__codelineno-4-2" href = "#__codelineno-4-2" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > []< / span > < span class = "kt" > any< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-3" name = "__codelineno-4-3" href = "#__codelineno-4-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-4-4" name = "__codelineno-4-4" href = "#__codelineno-4-4" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > New< / span > < span class = "p" > ()< / span >
< a id = "__codelineno-4-5" name = "__codelineno-4-5" href = "#__codelineno-4-5" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-6" name = "__codelineno-4-6" href = "#__codelineno-4-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个切片，用于保存遍历序列< / span >
< a id = "__codelineno-4-7" name = "__codelineno-4-7" href = "#__codelineno-4-7" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nb" > make< / span > < span class = "p" > ([]< / span > < span class = "kt" > any< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-8" name = "__codelineno-4-8" href = "#__codelineno-4-8" > < / a > < span class = "w" > < / span > < span class = "k" > for< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Len< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > > < / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-9" name = "__codelineno-4-9" href = "#__codelineno-4-9" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-4-10" name = "__codelineno-4-10" href = "#__codelineno-4-10" > < / a > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Remove< / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Front< / span > < span class = "p" > ()).(< / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-11" name = "__codelineno-4-11" href = "#__codelineno-4-11" > < / a > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-4-12" name = "__codelineno-4-12" href = "#__codelineno-4-12" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-13" name = "__codelineno-4-13" href = "#__codelineno-4-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-14" name = "__codelineno-4-14" href = "#__codelineno-4-14" > < / a > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-4-15" name = "__codelineno-4-15" href = "#__codelineno-4-15" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-16" name = "__codelineno-4-16" href = "#__codelineno-4-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-4-17" name = "__codelineno-4-17" href = "#__codelineno-4-17" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-18" name = "__codelineno-4-18" href = "#__codelineno-4-18" > < / a > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-4-19" name = "__codelineno-4-19" href = "#__codelineno-4-19" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-4-20" name = "__codelineno-4-20" href = "#__codelineno-4-20" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-4-21" name = "__codelineno-4-21" href = "#__codelineno-4-21" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-4-22" name = "__codelineno-4-22" href = "#__codelineno-4-22" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > nums< / span >
< a id = "__codelineno-4-23" name = "__codelineno-4-23" href = "#__codelineno-4-23" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.swift< / span > < pre > < span > < / span > < code > < a id = "__codelineno-5-1" name = "__codelineno-5-1" href = "#__codelineno-5-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-5-2" name = "__codelineno-5-2" href = "#__codelineno-5-2" > < / a > < span class = "kd" > func< / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > )< / span > < span class = "p" > -> < / span > < span class = "p" > [< / span > < span class = "nb" > Int< / span > < span class = "p" > ]< / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-3" name = "__codelineno-5-3" href = "#__codelineno-5-3" > < / a > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-5-4" name = "__codelineno-5-4" href = "#__codelineno-5-4" > < / a > < span class = "kd" > var< / span > < span class = "nv" > queue< / span > < span class = "p" > :< / span > < span class = "p" > [< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ]< / span > < span class = "p" > =< / span > < span class = "p" > [< / span > < span class = "n" > root< / span > < span class = "p" > ]< / span >
< a id = "__codelineno-5-5" name = "__codelineno-5-5" href = "#__codelineno-5-5" > < / a > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-5-6" name = "__codelineno-5-6" href = "#__codelineno-5-6" > < / a > < span class = "kd" > var< / span > < span class = "nv" > list< / span > < span class = "p" > :< / span > < span class = "p" > [< / span > < span class = "nb" > Int< / span > < span class = "p" > ]< / span > < span class = "p" > =< / span > < span class = "p" > []< / span >
< a id = "__codelineno-5-7" name = "__codelineno-5-7" href = "#__codelineno-5-7" > < / a > < span class = "k" > while< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "bp" > isEmpty< / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-8" name = "__codelineno-5-8" href = "#__codelineno-5-8" > < / a > < span class = "kd" > let< / span > < span class = "nv" > node< / span > < span class = "p" > =< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > removeFirst< / span > < span class = "p" > ()< / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-5-9" name = "__codelineno-5-9" href = "#__codelineno-5-9" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-5-10" name = "__codelineno-5-10" href = "#__codelineno-5-10" > < / a > < span class = "k" > if< / span > < span class = "kd" > let< / span > < span class = "nv" > left< / span > < span class = "p" > =< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-11" name = "__codelineno-5-11" href = "#__codelineno-5-11" > < / a > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-5-12" name = "__codelineno-5-12" href = "#__codelineno-5-12" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-5-13" name = "__codelineno-5-13" href = "#__codelineno-5-13" > < / a > < span class = "k" > if< / span > < span class = "kd" > let< / span > < span class = "nv" > right< / span > < span class = "p" > =< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-14" name = "__codelineno-5-14" href = "#__codelineno-5-14" > < / a > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-5-15" name = "__codelineno-5-15" href = "#__codelineno-5-15" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-5-16" name = "__codelineno-5-16" href = "#__codelineno-5-16" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-5-17" name = "__codelineno-5-17" href = "#__codelineno-5-17" > < / a > < span class = "k" > return< / span > < span class = "n" > list< / span >
< a id = "__codelineno-5-18" name = "__codelineno-5-18" href = "#__codelineno-5-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.js< / span > < pre > < span > < / span > < code > < a id = "__codelineno-6-1" name = "__codelineno-6-1" href = "#__codelineno-6-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-6-2" name = "__codelineno-6-2" href = "#__codelineno-6-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-3" name = "__codelineno-6-3" href = "#__codelineno-6-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-6-4" name = "__codelineno-6-4" href = "#__codelineno-6-4" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [< / span > < span class = "nx" > root< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-6-5" name = "__codelineno-6-5" href = "#__codelineno-6-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-6-6" name = "__codelineno-6-6" href = "#__codelineno-6-6" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-6-7" name = "__codelineno-6-7" href = "#__codelineno-6-7" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > length< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-8" name = "__codelineno-6-8" href = "#__codelineno-6-8" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > shift< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-6-9" name = "__codelineno-6-9" href = "#__codelineno-6-9" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-6-10" name = "__codelineno-6-10" href = "#__codelineno-6-10" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-6-11" name = "__codelineno-6-11" href = "#__codelineno-6-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-6-12" name = "__codelineno-6-12" href = "#__codelineno-6-12" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-6-13" name = "__codelineno-6-13" href = "#__codelineno-6-13" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-14" name = "__codelineno-6-14" href = "#__codelineno-6-14" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.ts< / span > < pre > < span > < / span > < code > < a id = "__codelineno-7-1" name = "__codelineno-7-1" href = "#__codelineno-7-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-7-2" name = "__codelineno-7-2" href = "#__codelineno-7-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > number< / span > < span class = "p" > []< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-3" name = "__codelineno-7-3" href = "#__codelineno-7-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-7-4" name = "__codelineno-7-4" href = "#__codelineno-7-4" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [< / span > < span class = "nx" > root< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-7-5" name = "__codelineno-7-5" href = "#__codelineno-7-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-7-6" name = "__codelineno-7-6" href = "#__codelineno-7-6" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > number< / span > < span class = "p" > []< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-7-7" name = "__codelineno-7-7" href = "#__codelineno-7-7" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > length< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-8" name = "__codelineno-7-8" href = "#__codelineno-7-8" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > shift< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "kr" > as< / span > < span class = "w" > < / span > < span class = "nx" > TreeNode< / span > < span class = "p" > ;< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-7-9" name = "__codelineno-7-9" href = "#__codelineno-7-9" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-7-10" name = "__codelineno-7-10" href = "#__codelineno-7-10" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-11" name = "__codelineno-7-11" href = "#__codelineno-7-11" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-7-12" name = "__codelineno-7-12" href = "#__codelineno-7-12" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-7-13" name = "__codelineno-7-13" href = "#__codelineno-7-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-14" name = "__codelineno-7-14" href = "#__codelineno-7-14" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-7-15" name = "__codelineno-7-15" href = "#__codelineno-7-15" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-7-16" name = "__codelineno-7-16" href = "#__codelineno-7-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-7-17" name = "__codelineno-7-17" href = "#__codelineno-7-17" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-7-18" name = "__codelineno-7-18" href = "#__codelineno-7-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.dart< / span > < pre > < span > < / span > < code > < a id = "__codelineno-8-1" name = "__codelineno-8-1" href = "#__codelineno-8-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-8-2" name = "__codelineno-8-2" href = "#__codelineno-8-2" > < / a > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-3" name = "__codelineno-8-3" href = "#__codelineno-8-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-8-4" name = "__codelineno-8-4" href = "#__codelineno-8-4" > < / a > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?> < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-8-5" name = "__codelineno-8-5" href = "#__codelineno-8-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-8-6" name = "__codelineno-8-6" href = "#__codelineno-8-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-8-7" name = "__codelineno-8-7" href = "#__codelineno-8-7" > < / a > < span class = "w" > < / span > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > res< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-8-8" name = "__codelineno-8-8" href = "#__codelineno-8-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > isNotEmpty< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-9" name = "__codelineno-8-9" href = "#__codelineno-8-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > removeFirst< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-8-10" name = "__codelineno-8-10" href = "#__codelineno-8-10" > < / a > < span class = "w" > < / span > < span class = "n" > res< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > !< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-8-11" name = "__codelineno-8-11" href = "#__codelineno-8-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-8-12" name = "__codelineno-8-12" href = "#__codelineno-8-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-8-13" name = "__codelineno-8-13" href = "#__codelineno-8-13" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-8-14" name = "__codelineno-8-14" href = "#__codelineno-8-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > res< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-8-15" name = "__codelineno-8-15" href = "#__codelineno-8-15" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.rs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-9-1" name = "__codelineno-9-1" href = "#__codelineno-9-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-9-2" name = "__codelineno-9-2" href = "#__codelineno-9-2" > < / a > < span class = "k" > fn< / span > < span class = "nf" > level_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > : < span class = "kp" > & < / span > < span class = "nc" > Rc< / span > < span class = "o" > < < / span > < span class = "n" > RefCell< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > > < / span > < span class = "p" > )< / span > < span class = "w" > < / span > -> < span class = "nb" > Vec< / span > < span class = "o" > < < / span > < span class = "kt" > i32< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-3" name = "__codelineno-9-3" href = "#__codelineno-9-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-9-4" name = "__codelineno-9-4" href = "#__codelineno-9-4" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > que< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > VecDeque< / span > ::< span class = "n" > new< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-9-5" name = "__codelineno-9-5" href = "#__codelineno-9-5" > < / a > < span class = "w" > < / span > < span class = "n" > que< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > Rc< / span > ::< span class = "n" > clone< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "n" > root< / span > < span class = "p" > ));< / span >
< a id = "__codelineno-9-6" name = "__codelineno-9-6" href = "#__codelineno-9-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-9-7" name = "__codelineno-9-7" href = "#__codelineno-9-7" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "nb" > Vec< / span > ::< span class = "n" > new< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-9-8" name = "__codelineno-9-8" href = "#__codelineno-9-8" > < / a >
< a id = "__codelineno-9-9" name = "__codelineno-9-9" href = "#__codelineno-9-9" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > que< / span > < span class = "p" > .< / span > < span class = "n" > pop_front< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-10" name = "__codelineno-9-10" href = "#__codelineno-9-10" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-9-11" name = "__codelineno-9-11" href = "#__codelineno-9-11" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-9-12" name = "__codelineno-9-12" href = "#__codelineno-9-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-13" name = "__codelineno-9-13" href = "#__codelineno-9-13" > < / a > < span class = "w" > < / span > < span class = "n" > que< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > Rc< / span > ::< span class = "n" > clone< / span > < span class = "p" > (< / span > < span class = "n" > left< / span > < span class = "p" > ));< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-9-14" name = "__codelineno-9-14" href = "#__codelineno-9-14" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-9-15" name = "__codelineno-9-15" href = "#__codelineno-9-15" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-16" name = "__codelineno-9-16" href = "#__codelineno-9-16" > < / a > < span class = "w" > < / span > < span class = "n" > que< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > Rc< / span > ::< span class = "n" > clone< / span > < span class = "p" > (< / span > < span class = "n" > right< / span > < span class = "p" > ));< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-9-17" name = "__codelineno-9-17" href = "#__codelineno-9-17" > < / a > < span class = "w" > < / span > < span class = "p" > };< / span >
< a id = "__codelineno-9-18" name = "__codelineno-9-18" href = "#__codelineno-9-18" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-9-19" name = "__codelineno-9-19" href = "#__codelineno-9-19" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span >
< a id = "__codelineno-9-20" name = "__codelineno-9-20" href = "#__codelineno-9-20" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.c< / span > < pre > < span > < / span > < code > < a id = "__codelineno-10-1" name = "__codelineno-10-1" href = "#__codelineno-10-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-10-2" name = "__codelineno-10-2" href = "#__codelineno-10-2" > < / a > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-3" name = "__codelineno-10-3" href = "#__codelineno-10-3" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助队列 */< / span >
< a id = "__codelineno-10-4" name = "__codelineno-10-4" href = "#__codelineno-10-4" > < / a > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "n" > front< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-5" name = "__codelineno-10-5" href = "#__codelineno-10-5" > < / a > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > arr< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-6" name = "__codelineno-10-6" href = "#__codelineno-10-6" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > node< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-7" name = "__codelineno-10-7" href = "#__codelineno-10-7" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > **< / span > < span class = "n" > queue< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-8" name = "__codelineno-10-8" href = "#__codelineno-10-8" > < / a >
< a id = "__codelineno-10-9" name = "__codelineno-10-9" href = "#__codelineno-10-9" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助队列 */< / span >
< a id = "__codelineno-10-10" name = "__codelineno-10-10" href = "#__codelineno-10-10" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > **< / span > < span class = "p" > )< / span > < span class = "n" > malloc< / span > < span class = "p" > (< / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "n" > MAX_SIZE< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-11" name = "__codelineno-10-11" href = "#__codelineno-10-11" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列指针< / span >
< a id = "__codelineno-10-12" name = "__codelineno-10-12" href = "#__codelineno-10-12" > < / a > < span class = "w" > < / span > < span class = "n" > front< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-13" name = "__codelineno-10-13" href = "#__codelineno-10-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 加入根节点< / span >
< a id = "__codelineno-10-14" name = "__codelineno-10-14" href = "#__codelineno-10-14" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-15" name = "__codelineno-10-15" href = "#__codelineno-10-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-10-16" name = "__codelineno-10-16" href = "#__codelineno-10-16" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助数组 */< / span >
< a id = "__codelineno-10-17" name = "__codelineno-10-17" href = "#__codelineno-10-17" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "p" > )< / span > < span class = "n" > malloc< / span > < span class = "p" > (< / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "n" > MAX_SIZE< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-18" name = "__codelineno-10-18" href = "#__codelineno-10-18" > < / a > < span class = "w" > < / span > < span class = "c1" > // 数组指针< / span >
< a id = "__codelineno-10-19" name = "__codelineno-10-19" href = "#__codelineno-10-19" > < / a > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-20" name = "__codelineno-10-20" href = "#__codelineno-10-20" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > front< / span > < span class = "w" > < / span > < span class = "o" > < < / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-21" name = "__codelineno-10-21" href = "#__codelineno-10-21" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-10-22" name = "__codelineno-10-22" href = "#__codelineno-10-22" > < / a > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > front< / span > < span class = "o" > ++< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-10-23" name = "__codelineno-10-23" href = "#__codelineno-10-23" > < / a > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-10-24" name = "__codelineno-10-24" href = "#__codelineno-10-24" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [< / span > < span class = "n" > index< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-25" name = "__codelineno-10-25" href = "#__codelineno-10-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-26" name = "__codelineno-10-26" href = "#__codelineno-10-26" > < / a > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-10-27" name = "__codelineno-10-27" href = "#__codelineno-10-27" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-28" name = "__codelineno-10-28" href = "#__codelineno-10-28" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-10-29" name = "__codelineno-10-29" href = "#__codelineno-10-29" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-30" name = "__codelineno-10-30" href = "#__codelineno-10-30" > < / a > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-10-31" name = "__codelineno-10-31" href = "#__codelineno-10-31" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-32" name = "__codelineno-10-32" href = "#__codelineno-10-32" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-10-33" name = "__codelineno-10-33" href = "#__codelineno-10-33" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-10-34" name = "__codelineno-10-34" href = "#__codelineno-10-34" > < / a > < span class = "w" > < / span > < span class = "c1" > // 更新数组长度的值< / span >
< a id = "__codelineno-10-35" name = "__codelineno-10-35" href = "#__codelineno-10-35" > < / a > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-36" name = "__codelineno-10-36" href = "#__codelineno-10-36" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > realloc< / span > < span class = "p" > (< / span > < span class = "n" > arr< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > ));< / span >
< a id = "__codelineno-10-37" name = "__codelineno-10-37" href = "#__codelineno-10-37" > < / a >
< a id = "__codelineno-10-38" name = "__codelineno-10-38" href = "#__codelineno-10-38" > < / a > < span class = "w" > < / span > < span class = "c1" > // 释放辅助数组空间< / span >
< a id = "__codelineno-10-39" name = "__codelineno-10-39" href = "#__codelineno-10-39" > < / a > < span class = "w" > < / span > < span class = "n" > free< / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-40" name = "__codelineno-10-40" href = "#__codelineno-10-40" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-41" name = "__codelineno-10-41" href = "#__codelineno-10-41" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.kt< / span > < pre > < span > < / span > < code > < a id = "__codelineno-11-1" name = "__codelineno-11-1" href = "#__codelineno-11-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-11-2" name = "__codelineno-11-2" href = "#__codelineno-11-2" > < / a > < span class = "kd" > fun< / span > < span class = "w" > < / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "w" > < / span > < span class = "n" > TreeNode?)< / span > < span class = "p" > :< / span > < span class = "w" > < / span > < span class = "n" > MutableList< / span > < span class = "o" > < < / span > < span class = "kt" > Int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-11-3" name = "__codelineno-11-3" href = "#__codelineno-11-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-11-4" name = "__codelineno-11-4" href = "#__codelineno-11-4" > < / a > < span class = "w" > < / span > < span class = "kd" > val< / span > < span class = "w" > < / span > < span class = "nv" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > LinkedList< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode?> < / span > < span class = "p" > ()< / span >
< a id = "__codelineno-11-5" name = "__codelineno-11-5" href = "#__codelineno-11-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > )< / span >
< a id = "__codelineno-11-6" name = "__codelineno-11-6" href = "#__codelineno-11-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-11-7" name = "__codelineno-11-7" href = "#__codelineno-11-7" > < / a > < span class = "w" > < / span > < span class = "kd" > val< / span > < span class = "w" > < / span > < span class = "nv" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > ArrayList< / span > < span class = "o" > < < / span > < span class = "kt" > Int< / span > < span class = "o" > > < / span > < span class = "p" > ()< / span >
< a id = "__codelineno-11-8" name = "__codelineno-11-8" href = "#__codelineno-11-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > isEmpty< / span > < span class = "p" > ())< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-11-9" name = "__codelineno-11-9" href = "#__codelineno-11-9" > < / a > < span class = "w" > < / span > < span class = "kd" > val< / span > < span class = "w" > < / span > < span class = "nv" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > poll< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-11-10" name = "__codelineno-11-10" href = "#__codelineno-11-10" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > ?.< / span > < span class = "na" > value< / span > < span class = "o" > !!< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-11-11" name = "__codelineno-11-11" href = "#__codelineno-11-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-11-12" name = "__codelineno-11-12" href = "#__codelineno-11-12" > < / a >
< a id = "__codelineno-11-13" name = "__codelineno-11-13" href = "#__codelineno-11-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-11-14" name = "__codelineno-11-14" href = "#__codelineno-11-14" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-11-15" name = "__codelineno-11-15" href = "#__codelineno-11-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span >
< a id = "__codelineno-11-16" name = "__codelineno-11-16" href = "#__codelineno-11-16" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.rb< / span > < pre > < span > < / span > < code > < a id = "__codelineno-12-1" name = "__codelineno-12-1" href = "#__codelineno-12-1" > < / a > < span class = "o" > [< / span > < span class = "n" > class< / span > < span class = "o" > ]< / span > < span class = "p" > {}< / span > < span class = "o" > -[< / span > < span class = "n" > func< / span > < span class = "o" > ]< / span > < span class = "p" > {< / span > < span class = "n" > level_order< / span > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.zig< / span > < pre > < span > < / span > < code > < a id = "__codelineno-13-1" name = "__codelineno-13-1" href = "#__codelineno-13-1" > < / a > < span class = "c1" > // 层序遍历< / span >
< a id = "__codelineno-13-2" name = "__codelineno-13-2" href = "#__codelineno-13-2" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > mem< / span > < span class = "p" > .< / span > < span class = "n" > Allocator< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > ArrayList< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-3" name = "__codelineno-13-3" href = "#__codelineno-13-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-13-4" name = "__codelineno-13-4" href = "#__codelineno-13-4" > < / a > < span class = "w" > < / span > < span class = "kr" > const< / span > < span class = "w" > < / span > < span class = "n" > L< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > TailQueue< / span > < span class = "p" > (< / span > < span class = "o" > *< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ));< / span >
< a id = "__codelineno-13-5" name = "__codelineno-13-5" href = "#__codelineno-13-5" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > L< / span > < span class = "p" > {};< / span >
< a id = "__codelineno-13-6" name = "__codelineno-13-6" href = "#__codelineno-13-6" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > root_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-13-7" name = "__codelineno-13-7" href = "#__codelineno-13-7" > < / a > < span class = "w" > < / span > < span class = "n" > root_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-13-8" name = "__codelineno-13-8" href = "#__codelineno-13-8" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span >
< a id = "__codelineno-13-9" name = "__codelineno-13-9" href = "#__codelineno-13-9" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-13-10" name = "__codelineno-13-10" href = "#__codelineno-13-10" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > ArrayList< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ).< / span > < span class = "n" > init< / span > < span class = "p" > (< / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > heap< / span > < span class = "p" > .< / span > < span class = "n" > page_allocator< / span > < span class = "p" > );< / span >
< a id = "__codelineno-13-11" name = "__codelineno-13-11" href = "#__codelineno-13-11" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > len< / span > < span class = "w" > < / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-12" name = "__codelineno-13-12" href = "#__codelineno-13-12" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > queue_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > popFirst< / span > < span class = "p" > ().< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-13-13" name = "__codelineno-13-13" href = "#__codelineno-13-13" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-13-14" name = "__codelineno-13-14" href = "#__codelineno-13-14" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-13-15" name = "__codelineno-13-15" href = "#__codelineno-13-15" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-16" name = "__codelineno-13-16" href = "#__codelineno-13-16" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-13-17" name = "__codelineno-13-17" href = "#__codelineno-13-17" > < / a > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-13-18" name = "__codelineno-13-18" href = "#__codelineno-13-18" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > tmp_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-13-19" name = "__codelineno-13-19" href = "#__codelineno-13-19" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-13-20" name = "__codelineno-13-20" href = "#__codelineno-13-20" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-21" name = "__codelineno-13-21" href = "#__codelineno-13-21" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-13-22" name = "__codelineno-13-22" href = "#__codelineno-13-22" > < / a > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-13-23" name = "__codelineno-13-23" href = "#__codelineno-13-23" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > tmp_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-13-24" name = "__codelineno-13-24" href = "#__codelineno-13-24" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span > < span class = "w" > < / span >
< a id = "__codelineno-13-25" name = "__codelineno-13-25" href = "#__codelineno-13-25" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-13-26" name = "__codelineno-13-26" href = "#__codelineno-13-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-13-27" name = "__codelineno-13-27" href = "#__codelineno-13-27" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< / div >
< / div >
< details class = "pythontutor" >
< summary > Code Visualization< / summary >
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< / details >
< h3 id = "2-complexity-analysis" > 2. Complexity analysis< a class = "headerlink" href = "#2-complexity-analysis" title = "Permanent link" > ¶ < / a > < / h3 >
< ul >
< li > < strong > Time complexity is < span class = "arithmatex" > \(O(n)\)< / span > < / strong > : All nodes are visited once, using < span class = "arithmatex" > \(O(n)\)< / span > time, where < span class = "arithmatex" > \(n\)< / span > is the number of nodes.< / li >
< li > < strong > Space complexity is < span class = "arithmatex" > \(O(n)\)< / span > < / strong > : In the worst case, i.e., a full binary tree, before traversing to the lowest level, the queue can contain at most < span class = "arithmatex" > \((n + 1) / 2\)< / span > nodes at the same time, occupying < span class = "arithmatex" > \(O(n)\)< / span > space.< / li >
< / ul >
< h2 id = "722-preorder-inorder-and-postorder-traversal" > 7.2.2 Preorder, inorder, and postorder traversal< a class = "headerlink" href = "#722-preorder-inorder-and-postorder-traversal" title = "Permanent link" > ¶ < / a > < / h2 >
< p > Correspondingly, preorder, inorder, and postorder traversal all belong to "depth-first traversal", also known as "depth-first search (DFS)", which embodies a "proceed to the end first, then backtrack and continue" traversal method.< / p >
< p > The Figure 7-10 shows the working principle of performing a depth-first traversal on a binary tree. < strong > Depth-first traversal is like walking around the perimeter of the entire binary tree< / strong > , encountering three positions at each node, corresponding to preorder traversal, inorder traversal, and postorder traversal.< / p >
< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/binary_tree_dfs.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "Preorder, inorder, and postorder traversal of a binary search tree" class = "animation-figure" src = "../binary_tree_traversal.assets/binary_tree_dfs.png" / > < / a > < / p >
< p align = "center" > Figure 7-10 Preorder, inorder, and postorder traversal of a binary search tree < / p >
< h3 id = "1-code-implementation_1" > 1. Code implementation< a class = "headerlink" href = "#1-code-implementation_1" title = "Permanent link" > ¶ < / a > < / h3 >
< p > Depth-first search is usually implemented based on recursion:< / p >
< div class = "tabbed-set tabbed-alternate" data-tabs = "2:14" > < input checked = "checked" id = "__tabbed_2_1" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_2" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_3" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_4" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_5" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_6" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_7" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_8" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_9" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_10" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_11" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_12" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_13" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_14" name = "__tabbed_2" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_2_1" > Python< / label > < label for = "__tabbed_2_2" > C++< / label > < label for = "__tabbed_2_3" > Java< / label > < label for = "__tabbed_2_4" > C#< / label > < label for = "__tabbed_2_5" > Go< / label > < label for = "__tabbed_2_6" > Swift< / label > < label for = "__tabbed_2_7" > JS< / label > < label for = "__tabbed_2_8" > TS< / label > < label for = "__tabbed_2_9" > Dart< / label > < label for = "__tabbed_2_10" > Rust< / label > < label for = "__tabbed_2_11" > C< / label > < label for = "__tabbed_2_12" > Kotlin< / label > < label for = "__tabbed_2_13" > Ruby< / label > < label for = "__tabbed_2_14" > Zig< / label > < / div >
< div class = "tabbed-content" >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.py< / span > < pre > < span > < / span > < code > < a id = "__codelineno-14-1" name = "__codelineno-14-1" href = "#__codelineno-14-1" > < / a > < span class = "k" > def< / span > < span class = "nf" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > ):< / span >
< a id = "__codelineno-14-2" name = "__codelineno-14-2" href = "#__codelineno-14-2" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 前序遍历" " " < / span >
< a id = "__codelineno-14-3" name = "__codelineno-14-3" href = "#__codelineno-14-3" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-14-4" name = "__codelineno-14-4" href = "#__codelineno-14-4" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-14-5" name = "__codelineno-14-5" href = "#__codelineno-14-5" > < / a > < span class = "c1" > # 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-14-6" name = "__codelineno-14-6" href = "#__codelineno-14-6" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-7" name = "__codelineno-14-7" href = "#__codelineno-14-7" > < / a > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-8" name = "__codelineno-14-8" href = "#__codelineno-14-8" > < / a > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-9" name = "__codelineno-14-9" href = "#__codelineno-14-9" > < / a >
< a id = "__codelineno-14-10" name = "__codelineno-14-10" href = "#__codelineno-14-10" > < / a > < span class = "k" > def< / span > < span class = "nf" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > ):< / span >
< a id = "__codelineno-14-11" name = "__codelineno-14-11" href = "#__codelineno-14-11" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 中序遍历" " " < / span >
< a id = "__codelineno-14-12" name = "__codelineno-14-12" href = "#__codelineno-14-12" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-14-13" name = "__codelineno-14-13" href = "#__codelineno-14-13" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-14-14" name = "__codelineno-14-14" href = "#__codelineno-14-14" > < / a > < span class = "c1" > # 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-14-15" name = "__codelineno-14-15" href = "#__codelineno-14-15" > < / a > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-16" name = "__codelineno-14-16" href = "#__codelineno-14-16" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-17" name = "__codelineno-14-17" href = "#__codelineno-14-17" > < / a > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-18" name = "__codelineno-14-18" href = "#__codelineno-14-18" > < / a >
< a id = "__codelineno-14-19" name = "__codelineno-14-19" href = "#__codelineno-14-19" > < / a > < span class = "k" > def< / span > < span class = "nf" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > ):< / span >
< a id = "__codelineno-14-20" name = "__codelineno-14-20" href = "#__codelineno-14-20" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 后序遍历" " " < / span >
< a id = "__codelineno-14-21" name = "__codelineno-14-21" href = "#__codelineno-14-21" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-14-22" name = "__codelineno-14-22" href = "#__codelineno-14-22" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-14-23" name = "__codelineno-14-23" href = "#__codelineno-14-23" > < / a > < span class = "c1" > # 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-14-24" name = "__codelineno-14-24" href = "#__codelineno-14-24" > < / a > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-25" name = "__codelineno-14-25" href = "#__codelineno-14-25" > < / a > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-14-26" name = "__codelineno-14-26" href = "#__codelineno-14-26" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.cpp< / span > < pre > < span > < / span > < code > < a id = "__codelineno-15-1" name = "__codelineno-15-1" href = "#__codelineno-15-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-15-2" name = "__codelineno-15-2" href = "#__codelineno-15-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-3" name = "__codelineno-15-3" href = "#__codelineno-15-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-15-4" name = "__codelineno-15-4" href = "#__codelineno-15-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-5" name = "__codelineno-15-5" href = "#__codelineno-15-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-15-6" name = "__codelineno-15-6" href = "#__codelineno-15-6" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-7" name = "__codelineno-15-7" href = "#__codelineno-15-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-8" name = "__codelineno-15-8" href = "#__codelineno-15-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-9" name = "__codelineno-15-9" href = "#__codelineno-15-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-15-10" name = "__codelineno-15-10" href = "#__codelineno-15-10" > < / a >
< a id = "__codelineno-15-11" name = "__codelineno-15-11" href = "#__codelineno-15-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-15-12" name = "__codelineno-15-12" href = "#__codelineno-15-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-13" name = "__codelineno-15-13" href = "#__codelineno-15-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-15-14" name = "__codelineno-15-14" href = "#__codelineno-15-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-15" name = "__codelineno-15-15" href = "#__codelineno-15-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-15-16" name = "__codelineno-15-16" href = "#__codelineno-15-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-17" name = "__codelineno-15-17" href = "#__codelineno-15-17" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-18" name = "__codelineno-15-18" href = "#__codelineno-15-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-19" name = "__codelineno-15-19" href = "#__codelineno-15-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-15-20" name = "__codelineno-15-20" href = "#__codelineno-15-20" > < / a >
< a id = "__codelineno-15-21" name = "__codelineno-15-21" href = "#__codelineno-15-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-15-22" name = "__codelineno-15-22" href = "#__codelineno-15-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-23" name = "__codelineno-15-23" href = "#__codelineno-15-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-15-24" name = "__codelineno-15-24" href = "#__codelineno-15-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-25" name = "__codelineno-15-25" href = "#__codelineno-15-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-15-26" name = "__codelineno-15-26" href = "#__codelineno-15-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-27" name = "__codelineno-15-27" href = "#__codelineno-15-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-28" name = "__codelineno-15-28" href = "#__codelineno-15-28" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-29" name = "__codelineno-15-29" href = "#__codelineno-15-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.java< / span > < pre > < span > < / span > < code > < a id = "__codelineno-16-1" name = "__codelineno-16-1" href = "#__codelineno-16-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-16-2" name = "__codelineno-16-2" href = "#__codelineno-16-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-3" name = "__codelineno-16-3" href = "#__codelineno-16-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-4" name = "__codelineno-16-4" href = "#__codelineno-16-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-5" name = "__codelineno-16-5" href = "#__codelineno-16-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-16-6" name = "__codelineno-16-6" href = "#__codelineno-16-6" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-7" name = "__codelineno-16-7" href = "#__codelineno-16-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-8" name = "__codelineno-16-8" href = "#__codelineno-16-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-9" name = "__codelineno-16-9" href = "#__codelineno-16-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-16-10" name = "__codelineno-16-10" href = "#__codelineno-16-10" > < / a >
< a id = "__codelineno-16-11" name = "__codelineno-16-11" href = "#__codelineno-16-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-16-12" name = "__codelineno-16-12" href = "#__codelineno-16-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-13" name = "__codelineno-16-13" href = "#__codelineno-16-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-14" name = "__codelineno-16-14" href = "#__codelineno-16-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-15" name = "__codelineno-16-15" href = "#__codelineno-16-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-16-16" name = "__codelineno-16-16" href = "#__codelineno-16-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-17" name = "__codelineno-16-17" href = "#__codelineno-16-17" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-18" name = "__codelineno-16-18" href = "#__codelineno-16-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-19" name = "__codelineno-16-19" href = "#__codelineno-16-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-16-20" name = "__codelineno-16-20" href = "#__codelineno-16-20" > < / a >
< a id = "__codelineno-16-21" name = "__codelineno-16-21" href = "#__codelineno-16-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-16-22" name = "__codelineno-16-22" href = "#__codelineno-16-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-23" name = "__codelineno-16-23" href = "#__codelineno-16-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-24" name = "__codelineno-16-24" href = "#__codelineno-16-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-25" name = "__codelineno-16-25" href = "#__codelineno-16-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-16-26" name = "__codelineno-16-26" href = "#__codelineno-16-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-27" name = "__codelineno-16-27" href = "#__codelineno-16-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-28" name = "__codelineno-16-28" href = "#__codelineno-16-28" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-29" name = "__codelineno-16-29" href = "#__codelineno-16-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.cs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-17-1" name = "__codelineno-17-1" href = "#__codelineno-17-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-17-2" name = "__codelineno-17-2" href = "#__codelineno-17-2" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > PreOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-3" name = "__codelineno-17-3" href = "#__codelineno-17-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-4" name = "__codelineno-17-4" href = "#__codelineno-17-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-17-5" name = "__codelineno-17-5" href = "#__codelineno-17-5" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "o" > !< / span > < span class = "p" > .< / span > < span class = "n" > Value< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-6" name = "__codelineno-17-6" href = "#__codelineno-17-6" > < / a > < span class = "w" > < / span > < span class = "n" > PreOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-7" name = "__codelineno-17-7" href = "#__codelineno-17-7" > < / a > < span class = "w" > < / span > < span class = "n" > PreOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-8" name = "__codelineno-17-8" href = "#__codelineno-17-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-17-9" name = "__codelineno-17-9" href = "#__codelineno-17-9" > < / a >
< a id = "__codelineno-17-10" name = "__codelineno-17-10" href = "#__codelineno-17-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-17-11" name = "__codelineno-17-11" href = "#__codelineno-17-11" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > InOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-12" name = "__codelineno-17-12" href = "#__codelineno-17-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-13" name = "__codelineno-17-13" href = "#__codelineno-17-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-17-14" name = "__codelineno-17-14" href = "#__codelineno-17-14" > < / a > < span class = "w" > < / span > < span class = "n" > InOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-15" name = "__codelineno-17-15" href = "#__codelineno-17-15" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "o" > !< / span > < span class = "p" > .< / span > < span class = "n" > Value< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-16" name = "__codelineno-17-16" href = "#__codelineno-17-16" > < / a > < span class = "w" > < / span > < span class = "n" > InOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-17" name = "__codelineno-17-17" href = "#__codelineno-17-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-17-18" name = "__codelineno-17-18" href = "#__codelineno-17-18" > < / a >
< a id = "__codelineno-17-19" name = "__codelineno-17-19" href = "#__codelineno-17-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-17-20" name = "__codelineno-17-20" href = "#__codelineno-17-20" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > PostOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-21" name = "__codelineno-17-21" href = "#__codelineno-17-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-22" name = "__codelineno-17-22" href = "#__codelineno-17-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-17-23" name = "__codelineno-17-23" href = "#__codelineno-17-23" > < / a > < span class = "w" > < / span > < span class = "n" > PostOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-24" name = "__codelineno-17-24" href = "#__codelineno-17-24" > < / a > < span class = "w" > < / span > < span class = "n" > PostOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-25" name = "__codelineno-17-25" href = "#__codelineno-17-25" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "o" > !< / span > < span class = "p" > .< / span > < span class = "n" > Value< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-26" name = "__codelineno-17-26" href = "#__codelineno-17-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.go< / span > < pre > < span > < / span > < code > < a id = "__codelineno-18-1" name = "__codelineno-18-1" href = "#__codelineno-18-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-18-2" name = "__codelineno-18-2" href = "#__codelineno-18-2" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-3" name = "__codelineno-18-3" href = "#__codelineno-18-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-4" name = "__codelineno-18-4" href = "#__codelineno-18-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-18-5" name = "__codelineno-18-5" href = "#__codelineno-18-5" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-18-6" name = "__codelineno-18-6" href = "#__codelineno-18-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-18-7" name = "__codelineno-18-7" href = "#__codelineno-18-7" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-8" name = "__codelineno-18-8" href = "#__codelineno-18-8" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-9" name = "__codelineno-18-9" href = "#__codelineno-18-9" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-10" name = "__codelineno-18-10" href = "#__codelineno-18-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-11" name = "__codelineno-18-11" href = "#__codelineno-18-11" > < / a >
< a id = "__codelineno-18-12" name = "__codelineno-18-12" href = "#__codelineno-18-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-18-13" name = "__codelineno-18-13" href = "#__codelineno-18-13" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-14" name = "__codelineno-18-14" href = "#__codelineno-18-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-15" name = "__codelineno-18-15" href = "#__codelineno-18-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-18-16" name = "__codelineno-18-16" href = "#__codelineno-18-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-18-17" name = "__codelineno-18-17" href = "#__codelineno-18-17" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-18-18" name = "__codelineno-18-18" href = "#__codelineno-18-18" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-19" name = "__codelineno-18-19" href = "#__codelineno-18-19" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-20" name = "__codelineno-18-20" href = "#__codelineno-18-20" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-21" name = "__codelineno-18-21" href = "#__codelineno-18-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-22" name = "__codelineno-18-22" href = "#__codelineno-18-22" > < / a >
< a id = "__codelineno-18-23" name = "__codelineno-18-23" href = "#__codelineno-18-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-18-24" name = "__codelineno-18-24" href = "#__codelineno-18-24" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-25" name = "__codelineno-18-25" href = "#__codelineno-18-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-26" name = "__codelineno-18-26" href = "#__codelineno-18-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-18-27" name = "__codelineno-18-27" href = "#__codelineno-18-27" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-18-28" name = "__codelineno-18-28" href = "#__codelineno-18-28" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-18-29" name = "__codelineno-18-29" href = "#__codelineno-18-29" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-30" name = "__codelineno-18-30" href = "#__codelineno-18-30" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-31" name = "__codelineno-18-31" href = "#__codelineno-18-31" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-32" name = "__codelineno-18-32" href = "#__codelineno-18-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.swift< / span > < pre > < span > < / span > < code > < a id = "__codelineno-19-1" name = "__codelineno-19-1" href = "#__codelineno-19-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-19-2" name = "__codelineno-19-2" href = "#__codelineno-19-2" > < / a > < span class = "kd" > func< / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-3" name = "__codelineno-19-3" href = "#__codelineno-19-3" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-4" name = "__codelineno-19-4" href = "#__codelineno-19-4" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-19-5" name = "__codelineno-19-5" href = "#__codelineno-19-5" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-6" name = "__codelineno-19-6" href = "#__codelineno-19-6" > < / a > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-19-7" name = "__codelineno-19-7" href = "#__codelineno-19-7" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-8" name = "__codelineno-19-8" href = "#__codelineno-19-8" > < / a > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-9" name = "__codelineno-19-9" href = "#__codelineno-19-9" > < / a > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-10" name = "__codelineno-19-10" href = "#__codelineno-19-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-11" name = "__codelineno-19-11" href = "#__codelineno-19-11" > < / a >
< a id = "__codelineno-19-12" name = "__codelineno-19-12" href = "#__codelineno-19-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-19-13" name = "__codelineno-19-13" href = "#__codelineno-19-13" > < / a > < span class = "kd" > func< / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-14" name = "__codelineno-19-14" href = "#__codelineno-19-14" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-15" name = "__codelineno-19-15" href = "#__codelineno-19-15" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-19-16" name = "__codelineno-19-16" href = "#__codelineno-19-16" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-17" name = "__codelineno-19-17" href = "#__codelineno-19-17" > < / a > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-19-18" name = "__codelineno-19-18" href = "#__codelineno-19-18" > < / a > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-19" name = "__codelineno-19-19" href = "#__codelineno-19-19" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-20" name = "__codelineno-19-20" href = "#__codelineno-19-20" > < / a > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-21" name = "__codelineno-19-21" href = "#__codelineno-19-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-22" name = "__codelineno-19-22" href = "#__codelineno-19-22" > < / a >
< a id = "__codelineno-19-23" name = "__codelineno-19-23" href = "#__codelineno-19-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-19-24" name = "__codelineno-19-24" href = "#__codelineno-19-24" > < / a > < span class = "kd" > func< / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-25" name = "__codelineno-19-25" href = "#__codelineno-19-25" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-26" name = "__codelineno-19-26" href = "#__codelineno-19-26" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-19-27" name = "__codelineno-19-27" href = "#__codelineno-19-27" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-28" name = "__codelineno-19-28" href = "#__codelineno-19-28" > < / a > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-19-29" name = "__codelineno-19-29" href = "#__codelineno-19-29" > < / a > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-30" name = "__codelineno-19-30" href = "#__codelineno-19-30" > < / a > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-31" name = "__codelineno-19-31" href = "#__codelineno-19-31" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-19-32" name = "__codelineno-19-32" href = "#__codelineno-19-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.js< / span > < pre > < span > < / span > < code > < a id = "__codelineno-20-1" name = "__codelineno-20-1" href = "#__codelineno-20-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-20-2" name = "__codelineno-20-2" href = "#__codelineno-20-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-20-3" name = "__codelineno-20-3" href = "#__codelineno-20-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-20-4" name = "__codelineno-20-4" href = "#__codelineno-20-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-20-5" name = "__codelineno-20-5" href = "#__codelineno-20-5" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-6" name = "__codelineno-20-6" href = "#__codelineno-20-6" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-7" name = "__codelineno-20-7" href = "#__codelineno-20-7" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-8" name = "__codelineno-20-8" href = "#__codelineno-20-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-20-9" name = "__codelineno-20-9" href = "#__codelineno-20-9" > < / a >
< a id = "__codelineno-20-10" name = "__codelineno-20-10" href = "#__codelineno-20-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-20-11" name = "__codelineno-20-11" href = "#__codelineno-20-11" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-20-12" name = "__codelineno-20-12" href = "#__codelineno-20-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-20-13" name = "__codelineno-20-13" href = "#__codelineno-20-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-20-14" name = "__codelineno-20-14" href = "#__codelineno-20-14" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-15" name = "__codelineno-20-15" href = "#__codelineno-20-15" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-16" name = "__codelineno-20-16" href = "#__codelineno-20-16" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-17" name = "__codelineno-20-17" href = "#__codelineno-20-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-20-18" name = "__codelineno-20-18" href = "#__codelineno-20-18" > < / a >
< a id = "__codelineno-20-19" name = "__codelineno-20-19" href = "#__codelineno-20-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-20-20" name = "__codelineno-20-20" href = "#__codelineno-20-20" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-20-21" name = "__codelineno-20-21" href = "#__codelineno-20-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-20-22" name = "__codelineno-20-22" href = "#__codelineno-20-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-20-23" name = "__codelineno-20-23" href = "#__codelineno-20-23" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-24" name = "__codelineno-20-24" href = "#__codelineno-20-24" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-25" name = "__codelineno-20-25" href = "#__codelineno-20-25" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-20-26" name = "__codelineno-20-26" href = "#__codelineno-20-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.ts< / span > < pre > < span > < / span > < code > < a id = "__codelineno-21-1" name = "__codelineno-21-1" href = "#__codelineno-21-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-21-2" name = "__codelineno-21-2" href = "#__codelineno-21-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-3" name = "__codelineno-21-3" href = "#__codelineno-21-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-4" name = "__codelineno-21-4" href = "#__codelineno-21-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-21-5" name = "__codelineno-21-5" href = "#__codelineno-21-5" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-21-6" name = "__codelineno-21-6" href = "#__codelineno-21-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-21-7" name = "__codelineno-21-7" href = "#__codelineno-21-7" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-8" name = "__codelineno-21-8" href = "#__codelineno-21-8" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-9" name = "__codelineno-21-9" href = "#__codelineno-21-9" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-10" name = "__codelineno-21-10" href = "#__codelineno-21-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-21-11" name = "__codelineno-21-11" href = "#__codelineno-21-11" > < / a >
< a id = "__codelineno-21-12" name = "__codelineno-21-12" href = "#__codelineno-21-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-21-13" name = "__codelineno-21-13" href = "#__codelineno-21-13" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-14" name = "__codelineno-21-14" href = "#__codelineno-21-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-15" name = "__codelineno-21-15" href = "#__codelineno-21-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-21-16" name = "__codelineno-21-16" href = "#__codelineno-21-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-21-17" name = "__codelineno-21-17" href = "#__codelineno-21-17" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-21-18" name = "__codelineno-21-18" href = "#__codelineno-21-18" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-19" name = "__codelineno-21-19" href = "#__codelineno-21-19" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-20" name = "__codelineno-21-20" href = "#__codelineno-21-20" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-21" name = "__codelineno-21-21" href = "#__codelineno-21-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-21-22" name = "__codelineno-21-22" href = "#__codelineno-21-22" > < / a >
< a id = "__codelineno-21-23" name = "__codelineno-21-23" href = "#__codelineno-21-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-21-24" name = "__codelineno-21-24" href = "#__codelineno-21-24" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-25" name = "__codelineno-21-25" href = "#__codelineno-21-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-21-26" name = "__codelineno-21-26" href = "#__codelineno-21-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-21-27" name = "__codelineno-21-27" href = "#__codelineno-21-27" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-21-28" name = "__codelineno-21-28" href = "#__codelineno-21-28" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-21-29" name = "__codelineno-21-29" href = "#__codelineno-21-29" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-30" name = "__codelineno-21-30" href = "#__codelineno-21-30" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-31" name = "__codelineno-21-31" href = "#__codelineno-21-31" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-21-32" name = "__codelineno-21-32" href = "#__codelineno-21-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.dart< / span > < pre > < span > < / span > < code > < a id = "__codelineno-22-1" name = "__codelineno-22-1" href = "#__codelineno-22-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-22-2" name = "__codelineno-22-2" href = "#__codelineno-22-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-22-3" name = "__codelineno-22-3" href = "#__codelineno-22-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-22-4" name = "__codelineno-22-4" href = "#__codelineno-22-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-22-5" name = "__codelineno-22-5" href = "#__codelineno-22-5" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-6" name = "__codelineno-22-6" href = "#__codelineno-22-6" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-7" name = "__codelineno-22-7" href = "#__codelineno-22-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-8" name = "__codelineno-22-8" href = "#__codelineno-22-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-22-9" name = "__codelineno-22-9" href = "#__codelineno-22-9" > < / a >
< a id = "__codelineno-22-10" name = "__codelineno-22-10" href = "#__codelineno-22-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-22-11" name = "__codelineno-22-11" href = "#__codelineno-22-11" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-22-12" name = "__codelineno-22-12" href = "#__codelineno-22-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-22-13" name = "__codelineno-22-13" href = "#__codelineno-22-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-22-14" name = "__codelineno-22-14" href = "#__codelineno-22-14" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-15" name = "__codelineno-22-15" href = "#__codelineno-22-15" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-16" name = "__codelineno-22-16" href = "#__codelineno-22-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-17" name = "__codelineno-22-17" href = "#__codelineno-22-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-22-18" name = "__codelineno-22-18" href = "#__codelineno-22-18" > < / a >
< a id = "__codelineno-22-19" name = "__codelineno-22-19" href = "#__codelineno-22-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-22-20" name = "__codelineno-22-20" href = "#__codelineno-22-20" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-22-21" name = "__codelineno-22-21" href = "#__codelineno-22-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-22-22" name = "__codelineno-22-22" href = "#__codelineno-22-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-22-23" name = "__codelineno-22-23" href = "#__codelineno-22-23" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-24" name = "__codelineno-22-24" href = "#__codelineno-22-24" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-25" name = "__codelineno-22-25" href = "#__codelineno-22-25" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-22-26" name = "__codelineno-22-26" href = "#__codelineno-22-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.rs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-23-1" name = "__codelineno-23-1" href = "#__codelineno-23-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-23-2" name = "__codelineno-23-2" href = "#__codelineno-23-2" > < / a > < span class = "k" > fn< / span > < span class = "nf" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > : < span class = "nb" > Option< / span > < span class = "o" > < & < / span > < span class = "n" > Rc< / span > < span class = "o" > < < / span > < span class = "n" > RefCell< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > > > < / span > < span class = "p" > )< / span > < span class = "w" > < / span > -> < span class = "nb" > Vec< / span > < span class = "o" > < < / span > < span class = "kt" > i32< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-3" name = "__codelineno-23-3" href = "#__codelineno-23-3" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "fm" > vec!< / span > < span class = "p" > [];< / span >
< a id = "__codelineno-23-4" name = "__codelineno-23-4" href = "#__codelineno-23-4" > < / a >
< a id = "__codelineno-23-5" name = "__codelineno-23-5" href = "#__codelineno-23-5" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-6" name = "__codelineno-23-6" href = "#__codelineno-23-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-23-7" name = "__codelineno-23-7" href = "#__codelineno-23-7" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-23-8" name = "__codelineno-23-8" href = "#__codelineno-23-8" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-9" name = "__codelineno-23-9" href = "#__codelineno-23-9" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-10" name = "__codelineno-23-10" href = "#__codelineno-23-10" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-23-11" name = "__codelineno-23-11" href = "#__codelineno-23-11" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span >
< a id = "__codelineno-23-12" name = "__codelineno-23-12" href = "#__codelineno-23-12" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-23-13" name = "__codelineno-23-13" href = "#__codelineno-23-13" > < / a >
< a id = "__codelineno-23-14" name = "__codelineno-23-14" href = "#__codelineno-23-14" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-23-15" name = "__codelineno-23-15" href = "#__codelineno-23-15" > < / a > < span class = "k" > fn< / span > < span class = "nf" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > : < span class = "nb" > Option< / span > < span class = "o" > < & < / span > < span class = "n" > Rc< / span > < span class = "o" > < < / span > < span class = "n" > RefCell< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > > > < / span > < span class = "p" > )< / span > < span class = "w" > < / span > -> < span class = "nb" > Vec< / span > < span class = "o" > < < / span > < span class = "kt" > i32< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-16" name = "__codelineno-23-16" href = "#__codelineno-23-16" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "fm" > vec!< / span > < span class = "p" > [];< / span >
< a id = "__codelineno-23-17" name = "__codelineno-23-17" href = "#__codelineno-23-17" > < / a >
< a id = "__codelineno-23-18" name = "__codelineno-23-18" href = "#__codelineno-23-18" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-19" name = "__codelineno-23-19" href = "#__codelineno-23-19" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-23-20" name = "__codelineno-23-20" href = "#__codelineno-23-20" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-21" name = "__codelineno-23-21" href = "#__codelineno-23-21" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-23-22" name = "__codelineno-23-22" href = "#__codelineno-23-22" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-23" name = "__codelineno-23-23" href = "#__codelineno-23-23" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-23-24" name = "__codelineno-23-24" href = "#__codelineno-23-24" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span >
< a id = "__codelineno-23-25" name = "__codelineno-23-25" href = "#__codelineno-23-25" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-23-26" name = "__codelineno-23-26" href = "#__codelineno-23-26" > < / a >
< a id = "__codelineno-23-27" name = "__codelineno-23-27" href = "#__codelineno-23-27" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-23-28" name = "__codelineno-23-28" href = "#__codelineno-23-28" > < / a > < span class = "k" > fn< / span > < span class = "nf" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > : < span class = "nb" > Option< / span > < span class = "o" > < & < / span > < span class = "n" > Rc< / span > < span class = "o" > < < / span > < span class = "n" > RefCell< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > > > < / span > < span class = "p" > )< / span > < span class = "w" > < / span > -> < span class = "nb" > Vec< / span > < span class = "o" > < < / span > < span class = "kt" > i32< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-29" name = "__codelineno-23-29" href = "#__codelineno-23-29" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "fm" > vec!< / span > < span class = "p" > [];< / span >
< a id = "__codelineno-23-30" name = "__codelineno-23-30" href = "#__codelineno-23-30" > < / a >
< a id = "__codelineno-23-31" name = "__codelineno-23-31" href = "#__codelineno-23-31" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nb" > Some< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-23-32" name = "__codelineno-23-32" href = "#__codelineno-23-32" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-23-33" name = "__codelineno-23-33" href = "#__codelineno-23-33" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-34" name = "__codelineno-23-34" href = "#__codelineno-23-34" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "o" > & < / span > < span class = "k" > mut< / span > < span class = "w" > < / span > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "n" > as_ref< / span > < span class = "p" > ()));< / span >
< a id = "__codelineno-23-35" name = "__codelineno-23-35" href = "#__codelineno-23-35" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > borrow< / span > < span class = "p" > ().< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-23-36" name = "__codelineno-23-36" href = "#__codelineno-23-36" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-23-37" name = "__codelineno-23-37" href = "#__codelineno-23-37" > < / a > < span class = "w" > < / span > < span class = "n" > result< / span >
< a id = "__codelineno-23-38" name = "__codelineno-23-38" href = "#__codelineno-23-38" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.c< / span > < pre > < span > < / span > < code > < a id = "__codelineno-24-1" name = "__codelineno-24-1" href = "#__codelineno-24-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-24-2" name = "__codelineno-24-2" href = "#__codelineno-24-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-24-3" name = "__codelineno-24-3" href = "#__codelineno-24-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-24-4" name = "__codelineno-24-4" href = "#__codelineno-24-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-5" name = "__codelineno-24-5" href = "#__codelineno-24-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-24-6" name = "__codelineno-24-6" href = "#__codelineno-24-6" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-7" name = "__codelineno-24-7" href = "#__codelineno-24-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-8" name = "__codelineno-24-8" href = "#__codelineno-24-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-9" name = "__codelineno-24-9" href = "#__codelineno-24-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-24-10" name = "__codelineno-24-10" href = "#__codelineno-24-10" > < / a >
< a id = "__codelineno-24-11" name = "__codelineno-24-11" href = "#__codelineno-24-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-24-12" name = "__codelineno-24-12" href = "#__codelineno-24-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-24-13" name = "__codelineno-24-13" href = "#__codelineno-24-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-24-14" name = "__codelineno-24-14" href = "#__codelineno-24-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-15" name = "__codelineno-24-15" href = "#__codelineno-24-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-24-16" name = "__codelineno-24-16" href = "#__codelineno-24-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-17" name = "__codelineno-24-17" href = "#__codelineno-24-17" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-18" name = "__codelineno-24-18" href = "#__codelineno-24-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-19" name = "__codelineno-24-19" href = "#__codelineno-24-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-24-20" name = "__codelineno-24-20" href = "#__codelineno-24-20" > < / a >
< a id = "__codelineno-24-21" name = "__codelineno-24-21" href = "#__codelineno-24-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-24-22" name = "__codelineno-24-22" href = "#__codelineno-24-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-24-23" name = "__codelineno-24-23" href = "#__codelineno-24-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-24-24" name = "__codelineno-24-24" href = "#__codelineno-24-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-25" name = "__codelineno-24-25" href = "#__codelineno-24-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-24-26" name = "__codelineno-24-26" href = "#__codelineno-24-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-27" name = "__codelineno-24-27" href = "#__codelineno-24-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-24-28" name = "__codelineno-24-28" href = "#__codelineno-24-28" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-24-29" name = "__codelineno-24-29" href = "#__codelineno-24-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.kt< / span > < pre > < span > < / span > < code > < a id = "__codelineno-25-1" name = "__codelineno-25-1" href = "#__codelineno-25-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-25-2" name = "__codelineno-25-2" href = "#__codelineno-25-2" > < / a > < span class = "kd" > fun< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "w" > < / span > < span class = "n" > TreeNode?)< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-25-3" name = "__codelineno-25-3" href = "#__codelineno-25-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-25-4" name = "__codelineno-25-4" href = "#__codelineno-25-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-25-5" name = "__codelineno-25-5" href = "#__codelineno-25-5" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > value< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-6" name = "__codelineno-25-6" href = "#__codelineno-25-6" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-7" name = "__codelineno-25-7" href = "#__codelineno-25-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-8" name = "__codelineno-25-8" href = "#__codelineno-25-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-25-9" name = "__codelineno-25-9" href = "#__codelineno-25-9" > < / a >
< a id = "__codelineno-25-10" name = "__codelineno-25-10" href = "#__codelineno-25-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-25-11" name = "__codelineno-25-11" href = "#__codelineno-25-11" > < / a > < span class = "kd" > fun< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "w" > < / span > < span class = "n" > TreeNode?)< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-25-12" name = "__codelineno-25-12" href = "#__codelineno-25-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-25-13" name = "__codelineno-25-13" href = "#__codelineno-25-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-25-14" name = "__codelineno-25-14" href = "#__codelineno-25-14" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-15" name = "__codelineno-25-15" href = "#__codelineno-25-15" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > value< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-16" name = "__codelineno-25-16" href = "#__codelineno-25-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-17" name = "__codelineno-25-17" href = "#__codelineno-25-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-25-18" name = "__codelineno-25-18" href = "#__codelineno-25-18" > < / a >
< a id = "__codelineno-25-19" name = "__codelineno-25-19" href = "#__codelineno-25-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-25-20" name = "__codelineno-25-20" href = "#__codelineno-25-20" > < / a > < span class = "kd" > fun< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "w" > < / span > < span class = "n" > TreeNode?)< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-25-21" name = "__codelineno-25-21" href = "#__codelineno-25-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-25-22" name = "__codelineno-25-22" href = "#__codelineno-25-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-25-23" name = "__codelineno-25-23" href = "#__codelineno-25-23" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-24" name = "__codelineno-25-24" href = "#__codelineno-25-24" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-25" name = "__codelineno-25-25" href = "#__codelineno-25-25" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > value< / span > < span class = "p" > )< / span >
< a id = "__codelineno-25-26" name = "__codelineno-25-26" href = "#__codelineno-25-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.rb< / span > < pre > < span > < / span > < code > < a id = "__codelineno-26-1" name = "__codelineno-26-1" href = "#__codelineno-26-1" > < / a > < span class = "o" > [< / span > < span class = "n" > class< / span > < span class = "o" > ]< / span > < span class = "p" > {}< / span > < span class = "o" > -[< / span > < span class = "n" > func< / span > < span class = "o" > ]< / span > < span class = "p" > {< / span > < span class = "n" > pre_order< / span > < span class = "p" > }< / span >
< a id = "__codelineno-26-2" name = "__codelineno-26-2" href = "#__codelineno-26-2" > < / a >
< a id = "__codelineno-26-3" name = "__codelineno-26-3" href = "#__codelineno-26-3" > < / a > < span class = "o" > [< / span > < span class = "n" > class< / span > < span class = "o" > ]< / span > < span class = "p" > {}< / span > < span class = "o" > -[< / span > < span class = "n" > func< / span > < span class = "o" > ]< / span > < span class = "p" > {< / span > < span class = "n" > in_order< / span > < span class = "p" > }< / span >
< a id = "__codelineno-26-4" name = "__codelineno-26-4" href = "#__codelineno-26-4" > < / a >
< a id = "__codelineno-26-5" name = "__codelineno-26-5" href = "#__codelineno-26-5" > < / a > < span class = "o" > [< / span > < span class = "n" > class< / span > < span class = "o" > ]< / span > < span class = "p" > {}< / span > < span class = "o" > -[< / span > < span class = "n" > func< / span > < span class = "o" > ]< / span > < span class = "p" > {< / span > < span class = "n" > post_order< / span > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.zig< / span > < pre > < span > < / span > < code > < a id = "__codelineno-27-1" name = "__codelineno-27-1" href = "#__codelineno-27-1" > < / a > < span class = "c1" > // 前序遍历< / span >
< a id = "__codelineno-27-2" name = "__codelineno-27-2" href = "#__codelineno-27-2" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-27-3" name = "__codelineno-27-3" href = "#__codelineno-27-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-27-4" name = "__codelineno-27-4" href = "#__codelineno-27-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-27-5" name = "__codelineno-27-5" href = "#__codelineno-27-5" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-6" name = "__codelineno-27-6" href = "#__codelineno-27-6" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-7" name = "__codelineno-27-7" href = "#__codelineno-27-7" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-8" name = "__codelineno-27-8" href = "#__codelineno-27-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-27-9" name = "__codelineno-27-9" href = "#__codelineno-27-9" > < / a >
< a id = "__codelineno-27-10" name = "__codelineno-27-10" href = "#__codelineno-27-10" > < / a > < span class = "c1" > // 中序遍历< / span >
< a id = "__codelineno-27-11" name = "__codelineno-27-11" href = "#__codelineno-27-11" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-27-12" name = "__codelineno-27-12" href = "#__codelineno-27-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-27-13" name = "__codelineno-27-13" href = "#__codelineno-27-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-27-14" name = "__codelineno-27-14" href = "#__codelineno-27-14" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-15" name = "__codelineno-27-15" href = "#__codelineno-27-15" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-16" name = "__codelineno-27-16" href = "#__codelineno-27-16" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-17" name = "__codelineno-27-17" href = "#__codelineno-27-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-27-18" name = "__codelineno-27-18" href = "#__codelineno-27-18" > < / a >
< a id = "__codelineno-27-19" name = "__codelineno-27-19" href = "#__codelineno-27-19" > < / a > < span class = "c1" > // 后序遍历< / span >
< a id = "__codelineno-27-20" name = "__codelineno-27-20" href = "#__codelineno-27-20" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-27-21" name = "__codelineno-27-21" href = "#__codelineno-27-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-27-22" name = "__codelineno-27-22" href = "#__codelineno-27-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-27-23" name = "__codelineno-27-23" href = "#__codelineno-27-23" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-24" name = "__codelineno-27-24" href = "#__codelineno-27-24" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-25" name = "__codelineno-27-25" href = "#__codelineno-27-25" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-27-26" name = "__codelineno-27-26" href = "#__codelineno-27-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< / div >
< / div >
< details class = "pythontutor" >
< summary > Code Visualization< / summary >
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< / details >
< div class = "admonition tip" >
< p class = "admonition-title" > Tip< / p >
< p > Depth-first search can also be implemented based on iteration, interested readers can study this on their own.< / p >
< / div >
< p > The Figure 7-11 shows the recursive process of preorder traversal of a binary tree, which can be divided into two opposite parts: "recursion" and "return".< / p >
< ol >
< li > "Recursion" means starting a new method, the program accesses the next node in this process.< / li >
< li > "Return" means the function returns, indicating the current node has been fully accessed.< / li >
< / ol >
< div class = "tabbed-set tabbed-alternate" data-tabs = "3:11" > < input checked = "checked" id = "__tabbed_3_1" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_2" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_3" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_4" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_5" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_6" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_7" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_8" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_9" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_10" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_11" name = "__tabbed_3" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_3_1" > < 1> < / label > < label for = "__tabbed_3_2" > < 2> < / label > < label for = "__tabbed_3_3" > < 3> < / label > < label for = "__tabbed_3_4" > < 4> < / label > < label for = "__tabbed_3_5" > < 5> < / label > < label for = "__tabbed_3_6" > < 6> < / label > < label for = "__tabbed_3_7" > < 7> < / label > < label for = "__tabbed_3_8" > < 8> < / label > < label for = "__tabbed_3_9" > < 9> < / label > < label for = "__tabbed_3_10" > < 10> < / label > < label for = "__tabbed_3_11" > < 11> < / label > < / div >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step1.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "The recursive process of preorder traversal" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step1.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step2.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step2" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step2.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step3.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step3" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step3.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step4.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step4" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step4.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step5.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step5" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step5.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step6.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step6" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step6.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step7.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step7" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step7.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step8.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step8" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step8.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step9.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step9" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step9.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step10.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step10" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step10.png" / > < / a > < / p >
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< p > < a class = "glightbox" href = "../binary_tree_traversal.assets/preorder_step11.png" data-type = "image" data-width = "100%" data-height = "auto" data-desc-position = "bottom" > < img alt = "preorder_step11" class = "animation-figure" src = "../binary_tree_traversal.assets/preorder_step11.png" / > < / a > < / p >
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< / div >
< p align = "center" > Figure 7-11 The recursive process of preorder traversal < / p >
< h3 id = "2-complexity-analysis_1" > 2. Complexity analysis< a class = "headerlink" href = "#2-complexity-analysis_1" title = "Permanent link" > ¶ < / a > < / h3 >
< ul >
< li > < strong > Time complexity is < span class = "arithmatex" > \(O(n)\)< / span > < / strong > : All nodes are visited once, using < span class = "arithmatex" > \(O(n)\)< / span > time.< / li >
< li > < strong > Space complexity is < span class = "arithmatex" > \(O(n)\)< / span > < / strong > : In the worst case, i.e., the tree degrades into a linked list, the recursion depth reaches < span class = "arithmatex" > \(n\)< / span > , the system occupies < span class = "arithmatex" > \(O(n)\)< / span > stack frame space.< / li >
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