我的算法之路30--对称的二叉树

# -*- 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 not pRoot:
            return True
        return self.dp(pRoot.left,pRoot.right)
    def dp(self,left,right):
        if not  left and not right:
            return True
        if left and right and left.val==right.val:
            return self.dp(left.left,right.right) and self.dp(left.right,right.left)
        return False