FatMouse' Trade

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FatMouse' Trade

Time Limit : 2000/1000ms(Java/Other)   Memory Limit : 65536/32768K (Java/Other)

Total Submission(s) : 6   AcceptedSubmission(s) : 4

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Problem Description

FatMouseprepared M pounds of cat food, ready to tradewith the cats guarding the warehouse containing his favorite food, JavaBean.
The warehouse has N rooms. The i-th roomcontains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to(不用) trade for all the JavaBeans in the room, instead, hemay getJ[i]* a% pounds of JavaBeans if he paysF[i]* a% pounds of cat food. Here a is a realnumber. Now he is assigning this homework to you: tell himthe maximum amount of JavaBeans he can obtain.

Input

The inputconsists of multiple test cases. Each test case begins with a line containingtwonon-negative integers M and N. Then N lines follow, each contains two non-negativeintegers J[i] and F[i] respectively. The last test case is followed by two-1's. All integersarenot greater than 1000.

Output

For each testcase, print in a single line a real numberaccurateup to 3(精确到小数点后三位) decimal places, which is the maximum amount of JavaBeansthat 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

Author

CHEN, Yue

Source

ZJCPC2004 

//*************************//* 任务介绍:交易        *//* 作者: 何香           *//* 完成时间:2013.10.18  *//*************************#include<iostream>#include<iomanip>using namespace std;int main (){int M,N,i,j;//M是所有的catfood,N是一共有N个roomdouble A[1002];//记录第i个room平均1 food换的javabean的数目int J[1002],F[1002];//Javabean的数目,catfood的数目while(cin>>M>>N){if(M!=(-1)||N!=(-1)){int t1,t2;double t;//输入每个房里Javabean和food的数目for(i=1;i<=N;++i){cin>>J[i]>>F[i];A[i]=1.0*J[i]/F[i];}//用冒泡排序法把平均值的大小由大到小排序,同时也使J和F也重新排序for(i=1;i<N;++i){for(j=1;j<=N-i;++j)if(A[j]<A[j+1]){t=A[j],t1=J[j];t2=F[j];A[j]=A[j+1],J[j]=J[j+1],F[j]=F[j+1];A[j+1]=t,J[j+1]=t1,F[j+1]=t2;}}int m=0;//记录所加的catfood的数目int temp;double max_J=0;//记录最大的Javabean数目//计算达到M时最大的Javabean/*for(i=1;i<=N;++i){m=temp;m=m+F[i];if(m<=M){max_J=max_J+J[i];}if(m=M){max_J=max_J+J[i];break;}else{t=1.0*(M-temp)/F[i];max_J=max_J+J[i]*t;break;}}*/for(i=1;i<=N;++i){if(M>=F[i]){max_J+=J[i];M-=F[i];}else{t=1.0*M/F[i];max_J+=J[i]*t;M=0;}}cout<<setiosflags(ios::fixed)<<setprecision(3);cout<<max_J<<endl;}elsebreak;}return 0;}


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