摘要：
Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.分析：这一题是说求出二叉树的最大深度，很显然我们会想到递归，很容易实现。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *... 阅读全文
摘要：
Given an array of integers, every element appearstwiceexcept for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?分析：给出一组数组，每个元素都出现两次，只有一个元素只出现一次。要求不需要额外的存储空间，时间复杂度是O(n)。我们想到一个性质：任何一个数字与自己异或的结果都为0，故可以想到数组中一个元素出现两 阅读全文