[LeetCode]题解(python):101 Symmetric tree
题目来源
https://leetcode.com/problems/symmetric-tree/
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
题意分析
Input:一个二叉树
Output:True or False
Conditions: 判断一个二叉树是不是对称的
题目思路
一一对应判断值是否相等,注意要清楚谁对应谁。
AC代码(Python)
1 # Definition for a binary tree node. 2 # class TreeNode(object): 3 # def __init__(self, x): 4 # self.val = x 5 # self.left = None 6 # self.right = None 7 8 class Solution(object): 9 def isSymmetric(self, root): 10 """ 11 :type root: TreeNode 12 :rtype: bool 13 """ 14 def help(p, q): 15 if p == None and q == None: 16 return True 17 if p and q and p.val == q.val: 18 return help(p.left, q.right) and help(p.right, q.left) 19 return False 20 21 if root: 22 return help(root.left, root.right) 23 return True 24