1 public class Solution {
 2     public int NumberOf1(int n) {
 3         int count = 0;
 4         int flag = 1;
 5         while (flag != 0) {
 6             if ((n & flag) != 0) {
 7                 count++;
 8             }
 9             flag = flag << 1;
10         }
11         return count;
12     }
13 }