HDU 5310 Souvenir

Souvenir

 

 Accepts: 901

 

 Submissions: 2743

 Time Limit: 2000/1000 MS (Java/Others)

 

 Memory Limit: 262144/262144 K (Java/Others)

Problem Description

Today is the 1st anniversary of BestCoder. Soda, the contest manager, wants to buy a souvenir for each contestant. You can buy the souvenir one by one or set by set in the shop. The price for a souvenir is p yuan and the price for a set of souvenirs if q yuan. There's m souvenirs in one set.There's n contestants in the contest today. Soda wants to know the minimum cost needed to buy a souvenir for each contestant.

Input

There are multiple test cases. The first line of input contains an integer T (1≤T≤105), indicating the number of test cases. For each test case:There's a line containing 4 integers n,m,p,q (1≤n,m,p,q≤104).

Output

For each test case, output the minimum cost needed.

Sample Input

2
1 2 2 1
1 2 3 4

Sample Output

1
3

Hint
For the first case, Soda can use 1 yuan to buy a set of 2 souvenirs.
For the second case, Soda can use 3 yuan to buy a souvenir.





#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>

using namespace std;

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        __int64 sum = 0;
        int n,m,p,q;
        scanf("%d%d%d%d",&n,&m,&p,&q);
        if(p*m<=q)
        {
            printf("%d\n",p*n);
        }
        else
        {
            sum = (n/m)*q;
            n = n%m;
            if(n*p<q)
            {
                printf("%I64d\n",sum+n*p);
            }
            else
            {
                printf("%I64d\n",sum+q);
            }
        }
    }
    return 0;
}