hello-algo/codes/java/chapter_tree/binary_tree_bfs.java
Yudong Jin 1c8b7ef559
refactor: Replace 结点 with 节点 (#452)
* Replace 结点 with 节点
Update the footnotes in the figures

* Update mindmap

* Reduce the size of the mindmap.png
2023-04-09 04:32:17 +08:00

41 lines
1.3 KiB
Java

/**
* File: binary_tree_bfs.java
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
*/
package chapter_tree;
import include.*;
import java.util.*;
public class binary_tree_bfs {
/* 层序遍历 */
static List<Integer> levelOrder(TreeNode root) {
// 初始化队列,加入根节点
Queue<TreeNode> queue = new LinkedList<>() {{ add(root); }};
// 初始化一个列表,用于保存遍历序列
List<Integer> list = new ArrayList<>();
while (!queue.isEmpty()) {
TreeNode 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;
}
public static void main(String[] args) {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode root = TreeNode.listToTree(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
System.out.println("\n初始化二叉树\n");
PrintUtil.printTree(root);
/* 层序遍历 */
List<Integer> list = levelOrder(root);
System.out.println("\n层序遍历的节点打印序列 = " + list);
}
}