目录

226. 翻转二叉树

思路

代码 

本地代码测试

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不管前方的路有多苦

只要走的方向正确

不管多么崎岖不平

都比站在原地更接近幸福

                        —— 24.10.21 

226. 翻转二叉树

给你一棵二叉树的根节点 root ，翻转这棵二叉树，并返回其根节点。

示例 1：

输入：root = [4,2,7,1,3,6,9]
输出：[4,7,2,9,6,3,1]

示例 2：

输入：root = [2,1,3]
输出：[2,3,1]

示例 3：

输入：root = []
输出：[]

思路

代码 

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode() {}*     TreeNode(int val) { this.val = val; }*     TreeNode(int val, TreeNode left, TreeNode right) {*         this.val = val;*         this.left = left;*         this.right = right;*     }* }*/
class Solution {public static TreeNode invertTree(TreeNode root) {fn(root);return root;}private static void fn(TreeNode root) {if (root == null) {return;}TreeNode temp = root.left;root.left = root.right;root.right = temp;fn(root.left);fn(root.right);}
}

本地代码测试

public class LeetCode226ReverseBinaryTree {public static TreeNode invertTree(TreeNode root) {fn(root);return root;}private static void fn(TreeNode root) {if (root == null) {return;}TreeNode temp = root.left;root.left = root.right;root.right = temp;fn(root.left);fn(root.right);}private static void Print(TreeNode root, String indent) {if (root == null) {return;}System.out.println(indent + root.value);Print(root.left, indent + "  |-- ");Print(root.right, indent + "  |-- ");}public static void main(String[] args) {TreeNode root = new TreeNode(1,new TreeNode(2,new TreeNode(4),new TreeNode(5,new TreeNode(7), null)),new TreeNode(3,null,new TreeNode(6)));TreeNode invertedRoot = invertTree(root);Print(invertedRoot,"");}
}