zoj 2109 FatMouse' Trade 贪心

#include<stdio.h>#include<string.h>#include<iostream>#include<algorithm>#include<math.h>using namespace std;struct data{    double j,f,x;}a[1024];bool cmp(data a,data b){    return a.x>b.x;}int main(){    int m,n,i;    double sum;    while(~scanf("%d %d",&m,&n))    {        if(m==-1&&n==-1) break;        for(i=0;i<n;i++)        {            scanf("%lf%lf",&a[i].j,&a[i].f);            a[i].x=a[i].j/a[i].f;        }        sum=0;        sort(a,a+n,cmp);        for(i=0;i<n;i++)        {            if(m>a[i].f)            {                sum+=a[i].j;                m-=a[i].f;            }            else            {                sum+=m*a[i].x;                m=0;                break;            }        }        printf("%.3f\n",sum);    }    return 0;}