hdu 1009：FatMouse' Trade

#include<iostream>
#include<algorithm>
#include<stdio.h>
using namespace std;

struct house
{
double get;
double pay;
} h[1111];

bool cmp(house a,house b)
{
return a.get/a.pay>b.get/b.pay;
}

int main()
{
int i,j;
int n;
int m;
double ans;
while(scanf("%d%d",&m,&n)!=EOF)
{
if(m==-1&&n==-1)break;
i=0;j=n;
while(j--)
{
scanf("%lf%lf",&h[i].get,&h[i].pay);
//        printf("%lf%lf\n",h[i].get,h[i].pay);
i++;
}
//printf("Jesus\n");
sort(h,h+n,cmp);
//printf("Yo man\n");
ans=0;i=0;
//for(i=0;i<n;i++)
for(i=0;i<n;i++)
{
if(m>=h[i].pay)
{ans+=h[i].get;m-=h[i].pay;}
else
{ans+=m/h[i].pay*h[i].get;break;}
//i++;
}
printf("%.3lf\n",ans);
}

return 0;
}

//0 1
//1 0
//1.000