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https://github.com/krahets/hello-algo.git
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feat: add Swift codes for binary_tree_traversal article
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parent
46429bcb23
commit
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5 changed files with 191 additions and 1 deletions
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@ -23,6 +23,8 @@ let package = Package(
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.executable(name: "hash_map", targets: ["hash_map"]),
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.executable(name: "array_hash_map", targets: ["array_hash_map"]),
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.executable(name: "binary_tree", targets: ["binary_tree"]),
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.executable(name: "binary_tree_bfs", targets: ["binary_tree_bfs"]),
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.executable(name: "binary_tree_dfs", targets: ["binary_tree_dfs"]),
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],
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targets: [
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.target(name: "utils", path: "utils"),
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@ -44,5 +46,7 @@ let package = Package(
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.executableTarget(name: "hash_map", dependencies: ["utils"], path: "chapter_hashing", sources: ["hash_map.swift"]),
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.executableTarget(name: "array_hash_map", path: "chapter_hashing", sources: ["array_hash_map.swift"]),
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.executableTarget(name: "binary_tree", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_tree.swift"]),
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.executableTarget(name: "binary_tree_bfs", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_tree_bfs.swift"]),
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.executableTarget(name: "binary_tree_dfs", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_tree_dfs.swift"]),
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]
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)
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42
codes/swift/chapter_tree/binary_tree_bfs.swift
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42
codes/swift/chapter_tree/binary_tree_bfs.swift
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@ -0,0 +1,42 @@
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/**
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* File: binary_tree_bfs.swift
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* Created Time: 2023-01-18
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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/* 层序遍历 */
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func hierOrder(root: TreeNode) -> [Int] {
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// 初始化队列,加入根结点
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var queue: [TreeNode] = [root]
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// 初始化一个列表,用于保存遍历序列
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var list: [Int] = []
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while !queue.isEmpty {
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let node = queue.removeFirst() // 队列出队
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list.append(node.val) // 保存结点
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if let left = node.left {
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queue.append(left) // 左子结点入队
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}
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if let right = node.right {
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queue.append(right) // 右子结点入队
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}
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}
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return list
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}
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@main
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enum BinaryTreeBFS {
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/* Driver Code */
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static func main() {
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/* 初始化二叉树 */
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// 这里借助了一个从数组直接生成二叉树的函数
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let node = TreeNode.listToTree(list: [1, 2, 3, 4, 5, 6, 7])!
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print("\n初始化二叉树\n")
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PrintUtil.printTree(root: node)
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/* 层序遍历 */
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let list = hierOrder(root: node)
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print("\n层序遍历的结点打印序列 = \(list)")
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}
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}
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70
codes/swift/chapter_tree/binary_tree_dfs.swift
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70
codes/swift/chapter_tree/binary_tree_dfs.swift
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@ -0,0 +1,70 @@
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/**
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* File: binary_tree_dfs.swift
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* Created Time: 2023-01-18
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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// 初始化列表,用于存储遍历序列
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var list: [Int] = []
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/* 前序遍历 */
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func preOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:根结点 -> 左子树 -> 右子树
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list.append(root.val)
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preOrder(root: root.left)
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preOrder(root: root.right)
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}
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/* 中序遍历 */
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func inOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:左子树 -> 根结点 -> 右子树
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inOrder(root: root.left)
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list.append(root.val)
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inOrder(root: root.right)
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}
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/* 后序遍历 */
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func postOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:左子树 -> 右子树 -> 根结点
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postOrder(root: root.left)
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postOrder(root: root.right)
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list.append(root.val)
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}
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@main
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enum BinaryTreeDFS {
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/* Driver Code */
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static func main() {
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/* 初始化二叉树 */
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// 这里借助了一个从数组直接生成二叉树的函数
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let root = TreeNode.listToTree(list: [1, 2, 3, 4, 5, 6, 7])!
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print("\n初始化二叉树\n")
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PrintUtil.printTree(root: root)
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/* 前序遍历 */
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list.removeAll()
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preOrder(root: root)
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print("\n前序遍历的结点打印序列 = \(list)")
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/* 中序遍历 */
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list.removeAll()
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inOrder(root: root)
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print("\n中序遍历的结点打印序列 = \(list)")
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/* 后序遍历 */
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list.removeAll()
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postOrder(root: root)
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print("\n后序遍历的结点打印序列 = \(list)")
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}
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}
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@ -14,4 +14,30 @@ public class TreeNode {
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val = x
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height = 0
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}
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public static func listToTree(list: [Int]) -> TreeNode? {
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let size = list.count
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if size == 0 {
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return nil
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}
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let root = TreeNode(x: list[0])
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var queue: [TreeNode] = [root]
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var i = 0
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while !queue.isEmpty {
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let node = queue.removeFirst()
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i += 1
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if i >= size {
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break
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}
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node.left = TreeNode(x: list[i])
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queue.append(node.left!)
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i += 1
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if i >= size {
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break
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}
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node.right = TreeNode(x: list[i])
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queue.append(node.right!)
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}
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return root
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}
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}
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@ -188,7 +188,24 @@ comments: true
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=== "Swift"
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```swift title="binary_tree_bfs.swift"
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/* 层序遍历 */
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func hierOrder(root: TreeNode) -> [Int] {
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// 初始化队列,加入根结点
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var queue: [TreeNode] = [root]
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// 初始化一个列表,用于保存遍历序列
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var list: [Int] = []
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while !queue.isEmpty {
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let node = queue.removeFirst() // 队列出队
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list.append(node.val) // 保存结点
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if let left = node.left {
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queue.append(left) // 左子结点入队
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}
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if let right = node.right {
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queue.append(right) // 右子结点入队
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}
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}
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return list
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}
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```
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## 前序、中序、后序遍历
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@ -452,7 +469,38 @@ comments: true
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=== "Swift"
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```swift title="binary_tree_dfs.swift"
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/* 前序遍历 */
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func preOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:根结点 -> 左子树 -> 右子树
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list.append(root.val)
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preOrder(root: root.left)
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preOrder(root: root.right)
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}
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/* 中序遍历 */
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func inOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:左子树 -> 根结点 -> 右子树
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inOrder(root: root.left)
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list.append(root.val)
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inOrder(root: root.right)
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}
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/* 后序遍历 */
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func postOrder(root: TreeNode?) {
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guard let root = root else {
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return
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}
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// 访问优先级:左子树 -> 右子树 -> 根结点
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postOrder(root: root.left)
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postOrder(root: root.right)
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list.append(root.val)
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}
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```
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!!! note
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