OJ-Problems-Source/HDOJ/1009_autoAC.cpp

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2016-08-12 10:05:27 +08:00
#include<stdio.h>
#include <memory.h>
#include<stdlib.h>
struct Exchange{
int room;
int javabean;
};
int cmp( const void *a , const void *b )
{
struct Exchange *c = (Exchange *)a;
struct Exchange *d = (Exchange *)b;
if (d->room*1.0/d->javabean > c->room*1.0/c->javabean)
return 1;
else if (d->room*1.0/d->javabean < c->room*1.0/c->javabean)
return -1;
else return 0;
}
double summation(Exchange* ex,int len,int javabeans)
{
double sum=0;
qsort(ex,len,sizeof(Exchange),cmp);
for(int i=0;i<len;i++)
{
if(javabeans-ex[i].javabean>0)
{
sum+=ex[i].room;
javabeans-=ex[i].javabean;
}
else
{
sum+=javabeans*1.0/ex[i].javabean*ex[i].room;
break;
}
}
return sum;
}
int main()
{
int m,n;
while(scanf("%d%d",&m,&n)!=EOF)
{
if(m==-1&&n==-1)
break;
Exchange* e=new Exchange[n];
for(int i=0;i<n;i++)
scanf("%d%d",&(e[i].room),&(e[i].javabean));
double result=summation(e,n,m);
printf("%.3lf\n",result);
}
return 0;
}