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.
用递归解决还是很简单的，上代码：
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
原文：http://www.cnblogs.com/liujinhong/p/5432741.html