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hdoj FatMouse' Trade 1009 (多重背包)

sullay 2023-04-20 阅读 65


FatMouse' Trade


Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 57207    Accepted Submission(s): 19174



Problem Description


FatMouse prepared M pounds of cat food, ready to trade with the cats guarding the warehouse containing his favorite food, JavaBean.
The warehouse has N rooms. The i-th room contains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to trade for all the JavaBeans in the room, instead, he may get J[i]* a% pounds of JavaBeans if he pays F[i]* a% pounds of cat food. Here a is a real number. Now he is assigning this homework to you: tell him the maximum amount of JavaBeans he can obtain.




Input


The input consists of multiple test cases. Each test case begins with a line containing two non-negative integers M and N. Then N lines follow, each contains two non-negative integers J[i] and F[i] respectively. The last test case is followed by two -1's. All integers are not greater than 1000.




Output


For each test case, print in a single line a real number accurate up to 3 decimal places, which is the maximum amount of JavaBeans that FatMouse can obtain.




Sample Input


5 3
7 2
4 3
5 2
20 3
25 18
24 15
15 10
-1 -1



Sample Output


13.333 31.500


 


#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
struct zz
{
	int v;
	int w;
	double c;
}q[1010];
int cmp(zz a,zz b)
{
	return a.c>b.c;
}
int main()
{
	int n,m,i,j;
	while(scanf("%d%d",&m,&n),n!=-1&&m!=-1)
	{
		for(i=1;i<=n;i++)
		{
			scanf("%d%d",&q[i].v,&q[i].w);
			q[i].c=q[i].v*1.0/q[i].w;
		}
		sort(q+1,q+n+1,cmp);
		double sum=0;
		for(i=1;i<=n;i++)
		{
			if(q[i].w<=m)
			{
				sum+=q[i].v;
				m-=q[i].w;
			}
			else
			{
				sum+=m*q[i].c;
				break;
			}
		}
		printf("%.3lf\n",sum);
	}
	return 0;
}


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