FatMouse prepared M pounds of cat food, ready to trade with the cats guarding the warehouse containing his favorite food, JavaBean.
The warehouse has N rooms. The i-th room contains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to trade for all the JavaBeans in the room, instead, he may get J[i]* a% pounds of JavaBeans if he pays F[i]* a% pounds of cat food. Here a is a real number. Now he is assigning this homework to you: tell him the maximum amount of JavaBeans he can obtain.
The warehouse has N rooms. The i-th room contains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to trade for all the JavaBeans in the room, instead, he may get J[i]* a% pounds of JavaBeans if he pays F[i]* a% pounds of cat food. Here a is a real number. Now he is assigning this homework to you: tell him the maximum amount of JavaBeans he can obtain.
5 3 7 2 4 3 5 2 20 3 25 18 24 15 15 10 -1 -1
13.333 31.500这是一道简单的贪心问题,比值不同,所以要先用比值大的
最后一步的时候要记得判定是否还有剩余,或者多出了
上代码~
#include<stdio.h>
#include<algorithm>
using namespace std;
struct f
{
double c;
int nai,cat;
};
bool pai(f x,f y)
{
if(x.c>y.c)
return true;
else
return false;
}
int main()
{
int m,zong,i,j=0,n,b;
f a[1005];
while(~scanf("%d%d",&zong,&m))
{
double r=0;
if(zong==-1&&m==-1)
{
break;
}
for(i=0;i<m;i++)
{
scanf("%d%d",&a[i].nai,&a[i].cat);
a[i].c=a[i].nai*1.0/a[i].cat;
}
sort(a,a+m,pai);
for(i=0;i<m;i++)
{
if(zong>a[i].cat||zong==a[i].cat)
{
r=a[i].nai+r;
zong=zong-a[i].cat;
}
else
{
r=zong*1.0*a[i].c+r;
zong=0;
if(zong==0)
{
break;
}
}
if(zong==0)
{
break;
}
}
printf("%.3lf\n",r);
}
return 0;
}