leetcode226 翻转二叉树——简单

# 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):
        def dfs(root):
            if root is None:
                return
            tmp=root.left
            root.left=root.right
            root.right=tmp
            dfs(root.left)
            dfs(root.right)
        dfs(root)
        return root

# 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):
        if root is None:
            return
        root.left,root.right=root.right,root.left
        self.invertTree(root.left)
        self.invertTree(root.right)
        return root