递归就几行

import java.util.*;

public class Main{
public static void main(String[] args){

    Scanner sc = new Scanner(System.in);
    int i = sc.nextInt();
    System.out.println(countOne(i));
}

public static int countOne(int a){
    return a == 0 ? 0 : a % 2 + countOne(a / 2);
}

}