题目

翻转一棵二叉树。

示例：
输入：
4
/ \
2 7
/ \ / \
1 3 6 9
输出：
4
/ \
7 2
/ \ / \
9 6 3 1

方案（递归）

  1. # Definition for a binary tree node.
  2. # class TreeNode:
  3. #     def __init__(self, x):
  4. #         self.val = x
  5. #         self.left = None
  6. #         self.right = None
  8. class Solution:
  9.     def invertTree(self, root: TreeNode) -> TreeNode:
  10.         if not root:
  11.             return root
  13.         root.left, root.right = root.right, root.left
  15.         self.invertTree(root.left)
  16.         self.invertTree(root.right)
  18.         return root

原文

https://leetcode-cn.com/explore/interview/card/2020-top-interview-questions/292/simulation/1308/