题解 | #求int型正整数在内存中存储时1的个数#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        scanner.useDelimiter("\n");
        int num = 0;
        if (scanner.hasNextInt()) {
            num = scanner.nextInt();
        }
        int res = 0;
        if (num==((1<<31)-1)) {
            System.out.println(31);
            return;
        }
        for (int i = 30; i >=0; i--) {
             if (num >= (1<<i)) {
                 num-= (1<<i);
                 res++; 
             }
        }
        System.out.println(res);
    }
}