HDU 1009 Fatmouse's trade

贪心+排序

#include <iostream>
#include<stdio.h>
#include<algorithm>
#include<math.h>
using namespace std;
int M,N;
struct wareroom
{
    int Javabean;
    int catfood;
    double balance;
};
wareroom room[100000];
int cmp(const void* a,const void* b)
{
    wareroom c=*(wareroom*)a;
    wareroom d=*(wareroom*)b;
    double temp=d.balance-c.balance;
    if(temp>0)return 1;
    else if(fabs(temp)<0.00001)return 0;
    else return -1;
}
int main()
{
    while(scanf("%d %d",&M,&N)!=EOF)
    {
        if(M==-1&& N==-1)break;
        int i;
        double sum=0;
        for(i=0;i<N;i++)
        {
            scanf("%d %d",&room[i].Javabean,&room[i].catfood);
            room[i].balance=((double)room[i].Javabean)/((double)room[i].catfood);
        }
        qsort(room,N,sizeof(room[0]),cmp);
        /*for(i=0;i<N;i++)
        {
            printf("%.3lf  ",room[i].balance);
        }*/
        for(i=0;i<N&&M>0;i++)
        {
            if(M>=room[i].catfood)
            {
                sum+=room[i].Javabean;
                M-=room[i].catfood;
            }else
            {
                sum+=((double)M)/((double)room[i].catfood)*room[i].Javabean;
                break;
            }
        }
        printf("%.3lf\n",sum);
    }
    return 0;
}