class Solution {public:    int singleNumber(int A[], int n) {        if(n <= 0 )            return 0;        int ans = 0;        for(int i = 0; i < 32; i++)        {            int q = 0;            for(int j = 0; j < n; j++)            {                int p = A[j] >> i & 1;                q = (q + p ) % 3;            }            ans = ans | q <<i;        }        return ans;    }};