hdu2187悼念512汶川大地震遇难同胞——老人是真饿了(贪心 简单题)

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简单题

 #include<bits/stdc++.h>
 using namespace std;
 struct node
 {
     double dan,weight;
 }a[];
 bool cmp(node x,node y)
 {
     return x.dan<y.dan;
 }
 void init()
 {
     for(int i=;i<;i++)
     {
         a[i].dan=0.0;a[i].weight=0.0;
     }
 }
 int main()
 {
     int c;
     while(~scanf("%d",&c))
     {
         while(c--)
         {
             double n;int m;
             scanf("%lf %d",&n,&m);
             init();
             for(int i=;i<m;i++)
             {
                 scanf("%lf %lf",&a[i].dan,&a[i].weight);
             }
             sort(a,a+m,cmp);double ans=;
             for(int i=;i<m;i++)
             {
                 if(n>)
                 {
                     if(n>=a[i].dan*a[i].weight)
                     {
                         n-=a[i].dan*a[i].weight;
                         ans=a[i].weight+ans;
                     }
                     else
                     {
                         ans=n/a[i].dan+ans;
                         n=;break;
                     }
                 }
             }
             printf("%.2lf\n",ans);
         }
     }
     return ;
 }