python-leetcode-翻转二叉树
226. 翻转二叉树 - 力扣（LeetCode）
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
if not root:
return None
# 交换左右子树
root.left, root.right = root.right, root.left
# 递归翻转左子树和右子树
self.invertTree(root.left)
self.invertTree(root.right)
return root