UVA 11021 C - Tribles(概率DP)

记忆化就可以搞定，比赛里都没做出来，真的是态度有问题啊。。。

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 using namespace std;
 double p[];
 double dp[];
 int flag[],n;
 double po(double a,int k)
 {
     double b = 1.0;
     while(k)
     {
         if(k&)
         b = a*b;
         a = a*a;
         k = k/;
     }
     return b;
 }
 double dfs(int step)
 {
     int i;
     if(flag[step])
     return dp[step];
     if(step == )
     return p[];
     double ans = p[],temp;
     for(i = ;i < n;i ++)
     {
         temp = p[i];
         temp *= po(dfs(step-),i);
         ans += temp;
     }
     flag[step] = ;
     return dp[step] = ans;
 }
 int main()
 {
     int t,cas = ,i,m,k;
     double ans,temp;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d%d%d",&n,&k,&m);
         memset(flag,,sizeof(flag));
         for(i = ;i < n;i ++)
         scanf("%lf",&p[i]);
         if(m == )
         {
             printf("Case #%d: %.7lf\n",cas++,0.0);
             continue;
         }
         ans = ;
         temp = dfs(m);
         for(i = ;i < k;i ++)
         ans *= temp;
         printf("Case #%d: %.7lf\n",cas++,ans);
     }
     return ;
 }