FatMouse

 

时间限制：1 秒

内存限制：128 兆

特殊判题：否

提交：1431

解决：641

题目描述：

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. 

输入：

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.

输出：

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.

样例输入：

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

样例输出：

13.333
31.500

 1 #include <iostream>

 2 #include <algorithm>

 3 #include <iomanip>

 4 using namespace std;

 5  

 6 struct goods

 7 {

 8    int J,F;

 9    double xinjia;

10 }buf[1000];

11  

12  

13 bool cmp(goods a,goods b)

14 {

15  

16     return  a.xinjia<b.xinjia;

17 }

18  

19  

20 int main()

21 {

22   int m,n,j,f;

23   while(cin>>m)

24   {

25      cin>>n;

26      if(m==-1&&n==-1) break;

27      int i;

28      for(i=0;i<n;i++)

29      {

30        cin>>j>>f;

31        buf[i].J=j;

32        buf[i].F=f;

33        buf[i].xinjia=(double)f/j;

34      }

35      sort(buf,buf+n,cmp);

36       

37      double sum=0.0;

38      for(i=0;i<n;i++)

39      {

40         if(buf[i].F<m)

41         {

42            sum=sum+buf[i].J;

43            m=m-buf[i].F;

44         }

45         else

46         {

47            sum=sum+buf[i].J*(double)m/buf[i].F;

48            break;

49         }

50      }

51  

52      cout<<fixed<<setprecision(3)<<sum<<endl;

53       

54      

55   }

56   return 0;

57 }

58  

59 /**************************************************************

60     Problem: 1433

61     User: 2009declan

62     Language: C++

63     Result: Accepted

64     Time:10 ms

65     Memory:1536 kb

66 ****************************************************************/