226. Invert Binary Tree

Invert a binary tree.

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

to

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

解题思路：

利用递归方式解决，左孩子为右递归，右孩子为左递归。

Java-Solution：

public class Solution {public TreeNode invertTree(TreeNode root) {if(root == null)return null;TreeNode temp = root.left;root.left = invertTree(root.right);root.right = invertTree(temp);return root;    }}