[NewCoder]求int型正整数在内存中存储时1的个数

import java.util.*;

public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int num = 0;
        String s = Integer.toBinaryString(n);
        
        for(int i = 0; i < s.length(); i++)
        {
            if(s.charAt(i) == ‘1‘)
                num += 1;
        }
        System.out.println(num);
    }
}

import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int count = 0;
        while(n != 0)
        {
            if(n % 2 == 1)
                count += 1;
            n /= 2;
        }
        System.out.println(count);
    }
}

import java.util.Scanner;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int count = 0;
        while (n != 0)
        {
//          数据n的二进制含有1的个数，可以通过n&(n-1)来循环计数判断。 
            n = n & (n-1);
            count ++;
        }        
        System.out.println(count);
    }
}