练习

package ys_0528;

// 空瓶换饮料
import java.util.Scanner;

public class Solution0601 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()){
            int bottle = scanner.nextInt();
            int ret = canDrink(bottle);
            System.out.println(ret);
        }
    }

    public static int canDrink(int bottle) {
        if (bottle < 2) {
            return 0;
        }
        if (bottle == 2){
            return 1;
        }
        return (bottle / 3) + canDrink((bottle / 3) + bottle % 3);
    }

}