#!/usr/bin/env python3

# -*- encoding: utf-8 -*-

"""

@FileName : invertTree.py

@Author : 56

@Description: https://leetcode-cn.com/problems/invert-binary-tree/

"""

from typing import List

# Definition for a binary tree node.

class TreeNode:

def __init__(self, x):

self.val = x

self.left = None

self.right = None

class Solution:

def invertTree(self, root: TreeNode) -> TreeNode:

if root == None:

return root

def dfs(node: TreeNode):

node.left, node.right = [node.right, node.left]

if node.left != None:

dfs(node.left)

if node.right != None:

dfs(node.right)

return node

return dfs(root)