LeetCode OJ 226. Invert Binary Tree

標籤：

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 sofuck off.

用遞迴解決還是很簡單的，上代碼：

 1 /** 2  * Definition for a binary tree node. 3  * public class TreeNode { 4  *     int val; 5  *     TreeNode left; 6  *     TreeNode right; 7  *     TreeNode(int x) { val = x; } 8  * } 9  */10 public class Solution {11     public TreeNode invertTree(TreeNode root) {12         if(root == null) return null;13         14         TreeNode left = invertTree(root.left);15         TreeNode right = invertTree(root.right);16         17         root.left = right;18         root.right = left;19         return root;20     }21 }

 

LeetCode OJ 226. Invert Binary Tree