CodeForces - 955A Feed the cat

After waking up at hh:mm, Andrew realised that he had forgotten to feed his only cat for yet another time (guess why there's only one cat). The cat's current hunger level is H points, moreover each minute without food increases his hunger by D points.

At any time Andrew can visit the store where tasty buns are sold (you can assume that is doesn't take time to get to the store and back). One such bun costs C roubles and decreases hunger by N points. Since the demand for bakery drops heavily in the evening, there is a special 20% discount for buns starting from 20:00 (note that the cost might become rational). Of course, buns cannot be sold by parts.

Determine the minimum amount of money Andrew has to spend in order to feed his cat. The cat is considered fed if its hunger level is less than or equal to zero.

Input

The first line contains two integers hh and mm (00 ≤ hh ≤ 23, 00 ≤ mm ≤ 59) — the time of Andrew's awakening.

The second line contains four integers H, D, C and N (1 ≤ H ≤ 105, 1 ≤ D, C, N ≤ 102).

Output

Output the minimum amount of money to within three decimal digits. You answer is considered correct, if its absolute or relative error does not exceed 10 - 4.

Formally, let your answer be a, and the jury's answer be b. Your answer is considered correct if .

   Examples  
     input           Copy     
19 00
255 1 100 1
     output    
25200.0000
     input           Copy     
17 41
1000 6 15 11
     output    
1365.0000

Note

In the first sample Andrew can visit the store at exactly 20:00. The cat's hunger will be equal to 315, hence it will be necessary to purchase 315 buns. The discount makes the final answer 25200 roubles.

In the second sample it's optimal to visit the store right after he wakes up. Then he'll have to buy 91 bins per 15 roubles each and spend a total of 1365 roubles.

题意：猫的主人在hh：mm起床，发现猫没喂，此时猫的饥饿值为H，每拖延一分钟增加D饥饿值，主人去买猫粮，C元一块，能消除D饥饿值，但是在8点整以后买会打8折。问使猫不饿的最小花费。

题解：八点之前，需要对等待打折和立刻购买之间取最小值（记住时间一定要求对！求法参见代码），八点之后，就是打折价也就是最小值。

代码：

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int hh,mm,h,d,c,n;
    scanf("%d%d%d%d%d%d",&hh,&mm,&h,&d,&c,&n);
    double a,b;
    int t;
    if(hh==0&&mm==0)hh=24;
    if(hh<20)
    {

        a=ceil(h/(double)n)*c;
        if(mm==0)
        t=(20-hh)*60+mm;
        else
            t=(20-hh-1)*60+mm;
        b=ceil((h+t*d)/(double)n)*(c*0.8);
    }
    else
    {
        t=0;
        a=b=ceil((h+t*d)/(double)n)*(c*0.8);
    }
    //printf("%.4lf\n",(h+t*d)/(double)n);
    if(a>b)
    printf("%.4lf\n",b);
    else printf("%.4lf\n",a);
    return 0;
}