LeetCode OJ - Single Number

题目：　

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?

解题思路：

　　对每一个数依次进行异或即可得到答案。

代码：

class Solution {
public:
    int singleNumber(int A[], int n) {
        int ans = 0;
        for (int i = 0; i < n; i++){
            ans ^= A[i];
        }
        return ans;
    }
};