位运算

x & -x = x & (~x + 1)
       x = 101...100...0
      ~x = 010...01....1
    ~x+1 = 010...10....0
x&(~x+1) = 0....010....0

C++ 代码

#include<iostream>

using namespace std;

int main(){
    int n, x;
    scanf("%d", &n);

    int res;
    while(n--){
        res = 0;
        scanf("%d", &x);
        for(int i = x; i; i -= i & -i) res++;
        cout << res << ' ';
    }

    return 0;
}