[leetcode] 101. Symmetric Tree 解题报告

题目链接：https://leetcode.com/problems/symmetric-tree/

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

思路：将左子树先遍历左子树，右子树先遍历右子树，看其是否相等即可！要注意判空！

今天去laurence买了一把epiphone dove pro吉他，好久没弹过了，手好痛啊。