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