LeetCode Single Number

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?

数组中有一个元素只出现一次，另外的元素都是出现两次，要求不使用额外的空间，在线性时间复杂度的要求下找出只出现一次的元素

使用抑或操作

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