位运算统计二进制1的个数（long）
bit count
http://www.nowcoder.com/questionTerminal/bc4c7936f5ed42cbb9131b6f39aa272b
#include<iostream>
using namespace std;
int main(){
unsigned long int num;
cin>>num;
int res=0;
while(num>0){
res+=num&1;
num>>=1;
}
cout << res << endl;
return 0;
}
