python实现剑指offer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。

# -*- 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
        return self.isSymBT(pRoot, pRoot)

    def isSymBT(self, tree1, tree2):
        if tree1 == None and tree2 == None:
            return True
        if tree1 == None or tree2 == None:
            return False
        if tree1.val != tree2.val:
            return False

        return self.isSymBT(tree1.left, tree2.right) and self.isSymBT(tree1.right, tree2.left)