【LeetCode with Python】 Symmetric Tree

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原题页面：https://oj.leetcode.com/problems/symmetric-tree/

题目类型：

难度评价：★

本文地址：/article/1377497.html

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree is symmetric:

1
   / \
  2   2
 / \ / \
3  4 4  3

But the following is not:

1
   / \
  2   2
   \   \
   3    3

Note:

Bonus points if you could solve it both recursively and iteratively.

confused what

"{1,#,2,3}"

means?
> read more on how binary tree is serialized on OJ.

class Solution:

    def checkSysmmetric(self, left, right):
        if None == left and None == right:
            return True
        elif None == left or None == right:
            return False
        elif left.val != right.val:
            return False
        return self.checkSysmmetric(left.left, right.right) and self.checkSysmmetric(left.right, right.left)

    # @param root, a tree node
    # @return a boolean
    def isSymmetric(self, root):
        if None == root:
            return True
        return self.checkSysmmetric(root.left, root.right)