题解 | #汽水瓶#

#include <iostream>
using namespace std;

int main() {
    int num;
    while (cin >> num) { // 注意 while 处理多个 case
        if(num == 0){
            break;
        }
        int full = 0;
        int empty = num;
        int res = 0;
        //cout<<empty<<endl;
        while (empty / 3 >= 1) {
            full = empty / 3;
            res += full;
            empty = full+empty%3;
            full = 0;
        }
        if (empty == 2) {
            res++;
        }
        cout << res << endl;
    }
}
// 64 位输出请用 printf("%lld")