hdu 1009 FatMouse' Trade （动态规划之贪心）

http://acm.hdu.edu.cn/showproblem.php?pid=1009

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

struct Trade
{
    int j,f;
    double percent;
}mouse[3001];
bool cmp(Trade a,Trade b)
{
    return a.percent>b.percent;
}
int main()
{
    int m,n,i;
    double sum;
    while(scanf("%d%d",&m,&n),m!=-1||n!=-1)
    {
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&mouse[i].j,&mouse[i].f);
            mouse[i].percent=1.0*mouse[i].j/mouse[i].f;
        }
        sort(mouse,mouse+n,cmp);
        sum=0;
        for(i=0;i<n;i++)
        {
            if(m>mouse[i].f)
            {
                sum+=mouse[i].j;
                m-=mouse[i].f;
            }
            else
            {
                sum+=mouse[i].percent *m;
                m=0;
                break;
            }
        }
        printf("%.3f\n",sum);
    }
    return 0;
}