_ Prove safety offer_ binary symmetrical binary tree

_ Binary symmetrical binary tree

Title Description
Please implement a function, a binary tree is used to determine not symmetrical. Note that if a binary image is a binary tree with this same definition as symmetrical.

Problem-solving ideas
just like a bunch of grapes has about two small bunch of grapes, remove the two small bunch of grapes to compare the size of grapes.
Answers

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