leetcode 226. Invert Binary Tree

226. Invert Binary Tree

 

QuestionEditorial Solution

 My Submissions

• Total Accepted: 108869
• Total Submissions: 229996
• Difficulty: Easy

Invert a binary tree.

     4   /   \  2     7 / \   / \1   3 6   9

to

     4   /   \  7     2 / \   / \9   6 3   1

Trivia:
This problem was inspired by this original tweet by Max Howell:

Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.

Subscribe to see which companies asked this question

Show Tags

Have you met this question in a real interview? 

Yes

 

No

Discuss Pick One

题意：反转二叉树

递归直接左右交换就可以了。。。。。

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {        public TreeNode invertTree(TreeNode root) {            if(root!=null)            {                TreeNode tmp=root.left;                root.left=root.right;                root.right=tmp;                invertTree(root.left);                invertTree(root.right);            }            return root;        }    }