43对称的二叉树

题目

43对称的二叉树

‘’’ 题目描述 请实现一个函数，用来判断一颗二叉树是不是对称的。注意，如果一个二叉树同此二叉树的镜像是同样的，定义其为对称的。 ‘’’

分析

实现

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
	def isSymmetrical(self, pRoot):
		# write code here
		if pRoot == None:
			return True

		def judgeSym(left, right):
			if left == None and right == None:
				return True
			elif left == None or right == None:
				return False
			if left.val == right.val:
				retLeft = judgeSym(left.left, right.right)
				retRight = judgeSym(left.right, right.left)
				return retLeft and retRight
			else:
				return False

		return judgeSym(pRoot.left, pRoot.right)