编辑代码

class Main {
	public static void main(String[] args) {
       ct(13);
	}
	public static void ct(int num)
	{
	if (num>0)
	{
	ct(num/2);
	if (num%2>0)
	System.out.print(1);
	else 
	System.out.print(0);
	}
	}
	}