求最低价格

#include <iostream>
using namespace std;
#define PRICE 8
double discount[5]={0,0.05,0.1,0.2,0.25};

double Caculate(int num1,int num2)        //计算该情况的价钱
{
double money,money1,money2;
money1=(PRICE-PRICE*discount[num1-1])*num1;
money2=(PRICE-PRICE*discount[num2-1])*num2;
money=money1+money2;
return money;
}
double Discount(int num)            //分情况讨论价钱
{
int k,yushu;
double money1,money2,min;
k=num/5;                    //取整
yushu=num%5;                //取余
min=num*PRICE;
switch(k)
{
case 0:
money1=(PRICE-PRICE*discount[num-1])*num;
break;
default:
if(yushu==0)
{
money1=(PRICE-PRICE*discount[4])*num;
return money1;
}
for(int i=1;i<(yushu+5);i++)
{
money1=Caculate(i,(yushu+5)-i);
if(money1<min)
min=money1;
}
if(num>9)
money2=(k-1)*5*(PRICE-PRICE*discount[4]);
else
money2=0;
return min+money2;
}
return money1;
}
int main(int argc, char* argv[])
{
int booknum;
double money;
cout<<"请输入购买书籍的数量：";
cin>>booknum;
money=Discount(booknum);
cout<<"最优惠的价格是"<<money<<"元"<<endl;
return 0;
}