Hot-226 翻转二叉树

1、dfs即可： 前序、中序、后序都可以

# 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]: # 递归交换左右子树 def dfs(Node): # 出口： if not Node: return # 前序就可以了 tmp = Node.left Node.left = Node.right Node.right = tmp dfs(Node.left) dfs(Node.right) dfs(root) return root