题解 | 汽水瓶

#include <iostream>
using namespace std;

int drink(int bottle){
    if(bottle < 2)
        return 0;
    if(bottle == 2)
        return 1;
    int res = bottle / 3;
    return res + drink(res + bottle%3);
}

int main() {

    int bottle = 0;
    while (cin>>bottle&&bottle != 0) {
        cout<<drink(bottle)<<endl;
    }
}
// 64 位输出请用 printf("%lld")