LeetCode : 136. Single Number

问题描述：

Given an array of integers, every element appears twice except 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：只要利用到 A^A = 0即可。

AC代码如下：

 int singleNumber(vector<int>& nums)     {        int ans = 0;        for(int i = 0;i < nums.size();i++)        {            ans = ans^nums[i];        }        return ans;    }