题解 | #汽水瓶#

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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            if (a == 0) {
                break;
            }
            int count = 0;
            int left = a % 3;
            int newEmpty = a / 3;
            count += newEmpty;
            // 临时变量，防止计算后被重新赋值
            int tempLeft = left;
            while (newEmpty + left >= 3) {
                left = (newEmpty + left) % 3;
                newEmpty = (newEmpty + tempLeft) / 3;
                count += newEmpty;
                tempLeft = left;
            }
            if (newEmpty + left == 2) {
                count++;
            }
            System.out.println(count);
        }
    }
}