hdu 3689 Infinite monkey theorem (KMP+DP)

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <cstring>
 4 #include <vector>
 5 #define N 1010
 6 #define M 30
 7 #define L 12
 8 #define mod 1000000007
 9 #define ui unsigned int
10 #define ll long long
11 #define dd double
12 #define idx(x) x-‘a‘+1
13 using namespace std;
14 
15 int T,n,m,len;
16 int nxt[L];
17 dd f[N][L],c[M];
18 char t[L];
19 void get_kmp()
20 {
21     int i=0,j=-1;
22     nxt[0]=-1;
23     while(i<len)
24     {
25         if(j==-1||t[i]==t[j])
26         {
27             i++;
28             j++;
29             nxt[i]=j;
30         }else{
31             j=nxt[j];
32         }
33     }
34 }
35 
36 dd solve()
37 {
38     f[0][0]=1;
39     for(int i=1;i<=m;i++)
40     {
41         for(int j=1;j<=len;j++)
42         {
43             for(int k=1;k<=26;k++)
44             {
45                 int p=j-1;
46                 while(p!=-1&&idx(t[p])!=k) p=nxt[p];
47                 f[i][p+1] += f[i-1][j-1]*c[k];
48             }
49         }
50     }
51     dd ans=0;
52     for(int i=1;i<=m;i++) ans+=f[i][len];
53     return ans*(dd)100;
54 }
55 
56 int main()
57 {
58     //freopen("aa.in","r",stdin);
59     while(1)
60     {
61         memset(f,0,sizeof(f));
62         memset(c,0,sizeof(c));
63         memset(nxt,0,sizeof(nxt));
64         scanf("%d%d",&n,&m);
65         if(n==0&&m==0) break;
66         for(int i=1;i<=n;i++)
67         {
68             scanf("%s",t);
69             scanf("%lf",&c[idx(t[0])]);
70         }
71         memset(t,0,sizeof(t));
72         scanf("%s",t);
73         len=strlen(t);
74         get_kmp();
75         printf("%.2lf",solve());
76         putchar(‘%‘);
77         puts("");
78     }
79     return 0;
80 }
81 
82     
83