single-number leetcode C++

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?

C++

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