LintCode: Single Number II

 1 class Solution {
 2 public:
 3     /**
 4      * @param A : An integer array
 5      * @return : An integer 
 6      */
 7     int singleNumberII(vector<int> &A) {
 8         // write your code here
 9         int count[32] = {0};
10         int res = 0;
11         for (int i = 0; i < 32; i++) {
12             for (auto &v : A) {
13                 count[i] += (v >> i) & 1;
14             }
15             res |= ((count[i] % 3) << i);
16         }
17         return res;
18     }
19 };