求一个数二进制中1的个数

暴力做法(与运算)

//0&0=0；0&1=0；1&0=0；1&1=1
#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
int k;
int main()
{
    int n;cin>>n;
    while (n -- )
    {
        int x;cin>>x;
        int k=0;
        while(x)
        {
            k+=x&1;
            x>>=1;
        }
         cout<<k<<" ";
    }

}

lowbit

#include <iostream>
#include <cstring>
#include <algorithm>
#define int long long
using namespace std;
int lowbit(int x)
{
    return x&-x;
}
signed main()
{
    int n;cin>>n;
    while(n--)
    {
        int x;cin>>x;
        int s=0;
        for(int i=x;i>0;i-=lowbit(i)) s++;
        cout<<s<<" ";
    }
    return 0;
}