Java [Leetcode 226]Invert Binary Tree

题目描述：

Invert a binary tree.

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

to

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

解题思路：

我只想说递归大法好。

代码如下：

/**
 * 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) {
    	TreeNode temp = null;
        if(root == null)
        	return null;
        else{
        	temp = invertTree(root.left);
        	root.left = invertTree(root.right);
        	root.right = temp;
        }
        return root;
    }
}