1、dfs即可 前序、中序、后序都可以# Definition for a binary tree node. # class TreeNode: # def __init__(self, val0, leftNone, rightNone): # 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