Leetcode226-翻转二叉树-Python实现

• 题目要求：

• 思路：

  • 递归
  • 走到底，如果以后节点存在，那么把以后节点的左节点右节点调换
  • 返回上一层
• 代码：

# Definition for a binary tree node.# class TreeNode:#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution:    def invertTree(self, root: TreeNode) -> TreeNode:        self.helper(root)        return root        def helper(self, node):        if node:            self.helper(node.left)            self.helper(node.right)            node.left, node.right = node.right, node.left