ZOJ 3948 Marjar Cola

Marjar Cola is on sale now! In order to attract more customers, Edward, the boss of Marjar Company, decides to launch a promotion: If a customer returns x empty cola bottles or y cola bottle caps to the company, he can get a full bottle of Marjar Cola for free!

Now, Alice has a empty cola bottles and b cola bottle caps, and she wants to drink as many bottles of cola as possible. Do you know how many full bottles of Marjar Cola she can drink?

Note that a bottle of cola consists of one cola bottle and one bottle cap.

x 个空可乐瓶或 y 个瓶盖可以换一瓶可乐（一瓶可乐包括一个可乐瓶以及一个瓶盖），已知有 a 个空瓶和 b 个瓶盖，问最多能换到多少瓶可乐?

解题思路

解法 1： 首先判断出无限喝可乐的情况，之后模拟空瓶（瓶盖）换可乐即可。

无限兑换的情况仅有 x=1 或 y=1 以及 x=y=2 & (a>=2 || b>=2) 。

解法 2： 鉴于上述无限兑换的情况可能容易想漏，故直接模拟也可以。由于 x, y, a, b 都较小，所以选择一个阈值作为上限，到达某个阈值即可视为他在无限兑换。

代码

#include<bits/stdc++.h>
using namespace std;
int x, y, a, b;
int solve()
{
int cnt = 0;
if(x == 1 || y == 1)    return -1;
if(x == 2 && y == 2 && (a>=2 || b>=2))  return -1;
while(a >= x || b >= y)
{
if(a >= x)  a-=x;
else if(b >= y) b -= y;
else    continue;
a++,    b++,    cnt++;
}
return cnt;
}
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
scanf("%d %d %d %d",&x, &y, &a,&b);
int ans = solve();
if(ans == -1)   printf("INF\n");
else printf("%d\n", ans);
}
}