COGS 1489玩纸牌

%%%http://blog.csdn.net/clover_hxy/article/details/53171234

 #include<bits/stdc++.h>
 #define LL long long
 #define LD long double
 #define  N 100005
 using namespace std;
 inline int ra()
 {
     int x=,f=; char ch=getchar();
     while (ch<'' || ch>'') {if (ch=='-') f=-; ch=getchar();}
     while (ch>='' && ch<='') {x=x*+ch-''; ch=getchar();}
     return x*f;
 }
 double d[][];
 int main()
 {
     freopen("expected.in","r",stdin);
     freopen("expected.out","w",stdout);
     int T=ra(),cnt=;
     while (T--)
     {
         int a,b,n;
         scanf("%d/%d%d",&a,&b,&n);
         double p=(double)a/b;
         memset(d,,sizeof(d));
         d[][]=1.0; d[][]=0.0;
         for (int i=; i<=n; i++)
             for (int j=; j*b<=a*i; j++)
             {
                 d[i][j]+=d[i-][j]*(-p);
                 if (j) d[i][j]+=d[i-][j-]*p;
             }
         double Q=0.0;
         for (int j=; j*b<=a*n; j++)
             Q+=d[n][j];
         int ans=floor(1.0/Q);
         printf("Case #%d: %d\n",++cnt,ans);
     }
     return ;
 }