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簡單題

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 struct node
 4 {
 5     double dan,weight;
 6 }a[1005];
 7 bool cmp(node x,node y)
 8 {
 9     return x.dan<y.dan;
10 }
11 void init()
12 {
13     for(int i=0;i<1005;i++)
14     {
15         a[i].dan=0.0;a[i].weight=0.0
 
;
16     }
17 }
18 int main()
19 {
20     int c;
21     while(~scanf("%d",&c))
22     {
23         while(c--)
24         {
25             double n;int m;
26             scanf("%lf %d",&n,&m);
27             init();
28             for(int i=0;i<m;i++)
29             {
30                 scanf("
 
%lf %lf",&a[i].dan,&a[i].weight);
31             }
32             sort(a,a+m,cmp);double ans=0;
33             for(int i=0;i<m;i++)
34             {
35                 if(n>0)
36                 {
37                     if(n>=a[i].dan*a[i].weight)
38                     {
39                         n-=a[i].dan*a[i].weight;
 
40                         ans=a[i].weight+ans;
41                     }
42                     else
43                     {
44                         ans=n/a[i].dan+ans;
45                         n=0;break;
46                     }
47                 }
48             }
49             printf("%.2lf\n",ans);
50         }
51     }
52     return 0;
53 }