hdu 1203 I NEED A OFFER!

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 using namespace std;
 5 
 6 int a[20000];
 7 double b[20000],dp[20000];
 8 int n,m;
 9 
10 int main()
11 {
12     while(scanf("%d%d",&n,&m)!=EOF)
13     {
14         memset(dp,0,sizeof(dp));
15         if(n==0&&m==0) break;
16         for(int i=1; i<=m; i++)
17         {
18             scanf("%d%lf",&a[i],&b[i]);
19             b[i]=1-b[i];
20         }
21         for(int i=0; i<=n; i++)
22         {
23             dp[i]=1;
24         }
25         for(int i=1; i<=m; i++)
26         {
27             for(int j=n; j>=a[i]; j--)
28             {
29                 dp[j]=min(dp[j],dp[j-a[i]]*b[i]);
30             }
31         }
32         printf("%.1lf%%\n",(1-dp[n])*100);
33     }
34     return 0;
35 }