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 {
public:
    int singleNumber(int A[], int n) {
        int i,res=A[0];
        for(i=1;i<n;i++){
            res=res^A[i];
        } 
        return res;
    }
};

Single Number