题解 | #汽水瓶#

#include <stdio.h>

int main() {
    int n;
    while (scanf("%d", &n) != EOF && n != 0) { 
        // 
        int count = 0;
        while(n>1)
        {
            if(n == 2)  //剩下2个瓶子
            {
                count++;  //+1
                break;
            }
            count += n/3;
            n = n/3 + n%3;  //剩下的空瓶子
        }
        printf("%d\n",count);
    }
    return 0;
}