FatMouse' Trade (贪心)

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 
 7 
 8 using namespace std;
 9 
10 struct node
11 {
12     double J;        // JavaBean
13     double F;        // Food
14     double rate;    // 性价比 
15 }arr[1000];
16 
17 bool cmp(node a, node b)
18 {
19     return a.rate > b.rate;
20 }
21 
22 int main() 
23 {
24     int m, n;
25     double a, b;
26     while(cin >> m >> n)
27     {
28         if(m == -1 && n == -1)
29             break;
30         
31         for(int i = 0; i < n; ++i)
32         {
33             cin >> arr[i].J >> arr[i].F;
34             arr[i].rate = (arr[i].J) / (arr[i].F);
35         }
36         
37         sort(arr, arr+n, cmp);
38         
39         double ans = 0;
40         for(int i = 0; i < n; ++i)
41         {
42             if(m > arr[i].F)
43             {
44                 ans += arr[i].J;
45                 m -= arr[i].F;
46             }
47             else
48             {
49                 ans += m*arr[i].rate;
50                 break;
51             }
52             
53         }
54         
55         printf("%0.3f\n", ans);
56         
57     }
58     
59             
60     return 0;
61 }