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?

class Solution {//异或操作的应用
public:
    int singleNumber(int A[], int n) {
        int i=0,result=A[0];
        while(i++<n-1)
            result=result^A[i];
        return result;
       
    }
};