版权声明： https://blog.csdn.net/Hu_WF/article/details/88736670
牛客网题目链接
# -*- coding:utf-8 -*-
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
# 返回镜像树的根节点
def Mirror(self, root):
# write code here
if root==None : return None
self.Mirror(root.left)
self.Mirror(root.right)
root.left,root.right =root.right,root.left