leetcode-226-翻转二叉树

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简介：leetcode-226-翻转二叉树

题目

https://leetcode.cn/problems/invert-binary-tree/description/?envType=study-plan-v2&envId=top-100-liked

题解

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# 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 noChild(self, root: Optional[TreeNode]):
        if root is None:
            return True
        elif root.left is None and root.right is None:
            return True
        else:
            return False
    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        if root is None or self.noChild(root):
            return root
        elif self.noChild(root.left) and self.noChild(root.right):
            temp = root.left
            root.left = root.right
            root.right = temp
            return root
        else:
            temp_l = self.invertTree(root.left)
            temp_r = self.invertTree(root.right)
            root.left =  temp_r
            root.right = temp_l
            return root