LeetCode OJ-- Single Number II **@

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;
}
};