题目链接

方法1 递归

image.png

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def invertTree(self, root: TreeNode) -> TreeNode:


        def digui(root):
            if not root:
                return 
            if root.left and root.right:    
                root.left,root.right=root.right,root.left
            
            elif root.left :
                root.right=root.left
                root.left=None
            elif root.right:
                root.left=root.right
                root.right=None
            else:
                return 
            digui(root.left)
            digui(root.right)

            return 


        digui(root)

        return root