226.InvertBinaryTree_JohnJim0816.py

#!/usr/bin/env python
# coding=utf-8
'''
@Author: John
@Email: johnjim0816@gmail.com
@Date: 2020-07-29 21:21:47
@LastEditor: John
@LastEditTime: 2020-07-29 21:22:09
@Discription: 
@Environment: 
'''
# Source : https://leetcode.com/problems/invert-binary-tree/
# Author : JohnJim0816
# Date : 2020-07-29

##################################################################################################### 
#
# Invert a binary tree.
# 
# Example:
# 
# Input:
# 
# 4
# / \
# 2 7
# / \ / \
# 1 3 6 9
# 
# Output:
# 
# 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 so f*** off.
#####################################################################################################

classSolution:
''' 递归
 '''
defmirrorTree(self, root: TreeNode) ->TreeNode:
ifnotroot:
returnNone
root.left, root.right=self.mirrorTree(root.right), self.mirrorTree(root.left)
returnroot