题解 | #汽水瓶#

import java.util.*;

public class Main{
    public static void main(String [] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int num = sc.nextInt();
            if( num != 0){
                     System.out.println(calc(num,0));
            }
       
        }
    }
    
    public static int calc(int num,int count){
        if(num < 2){
            return count;
        }
        if(num == 2){
            return ++count;
              
        }
        int a = num / 3; //换了多少瓶
        int b = num % 3; //还有多少个空瓶子
        return calc(a + b, count+a);
    }
}