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;
}
};