hello-algo/codes/kotlin/chapter_tree/binary_tree_bfs.kt
curtishd 4d9bbe72e1
Improve the consistency between code and comments in Kotlin (#1268)
* style(kotlin): Make code and comments consistent.

* style(kotlin): convert comment location.

* style(c): Add missing comment.

* style(kotlin): Remove redundant semicolon, parenthesis and brace

* style(kotlin): Put constants inside the function.

* style(kotlin): fix unnecessary indentation.

* style(swift): Add missing comment.

* style(kotlin): Add missing comment.

* style(kotlin): Remove redundant comment.

* style(kotlin): Add missing comment.

* Update linked_list.kt

* style(csharp,js,ts): Add missing comment.

* style(kotlin): Remove empty lines.

* Update list.cs

* Update list.js

* Update list.ts

* roll back to commit 1

* style(cs,js,ts): Add missing comment in docfile.

* style(kotlin): Use normal element swapping instead of scope functions.
2024-04-13 20:09:39 +08:00

42 lines
No EOL
1.1 KiB
Kotlin

/**
* File: binary_tree_bfs.kt
* Created Time: 2024-01-25
* Author: curtishd (1023632660@qq.com)
*/
package chapter_tree
import utils.TreeNode
import utils.printTree
import java.util.*
/* 层序遍历 */
fun levelOrder(root: TreeNode?): MutableList<Int> {
// 初始化队列,加入根节点
val queue = LinkedList<TreeNode?>()
queue.add(root)
// 初始化一个列表,用于保存遍历序列
val list = mutableListOf<Int>()
while (queue.isNotEmpty()) {
val node = queue.poll() // 队列出队
list.add(node?._val!!) // 保存节点值
if (node.left != null)
queue.offer(node.left) // 左子节点入队
if (node.right != null)
queue.offer(node.right) // 右子节点入队
}
return list
}
/* Driver Code */
fun main() {
/* 初始化二叉树 */
// 这里借助了一个从列表直接生成二叉树的函数
val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
println("\n初始化二叉树\n")
printTree(root)
/* 层序遍历 */
val list = levelOrder(root)
println("\n层序遍历的节点打印序列 = $list")
}