自动机之后按照自动机上的状态转移做dp就可以了
不用矩乘还是很良心

 1 const mo=10007;
 2 var q,f:array[0..10010] of longint;
 3     trie:array[0..10010,'A'..'Z'] of longint;
 4     can:array[0..10010] of boolean;
 5     dp:array[0..105,0..10010] of longint;
 6     l,k,s0,ss,i,n,m,j,t:longint;
 7     s:string;
 8     c:char;
 9 
10 procedure bfs;
11   var x,y,i,h,r:longint;
12       c:char;
13   begin
14     h:=1;
15     r:=0;
16     for c:='A' to 'Z' do
17       if trie[0,c]>0 then
18       begin
19         inc(r);
20         q[r]:=trie[0,c];
21       end;
22     while h<=r do
23     begin
24       x:=q[h];
25       for c:='A' to 'Z' do
26         if trie[x,c]>0 then
27         begin
28           y:=trie[x,c];
29           i:=f[x];
30           while (i>0) and (trie[i,c]=0) do i:=f[i];
31           if can[trie[i,c]] then can[y]:=true;  //这是一个易错点,考虑下shen和he这两个单词
32           f[y]:=trie[i,c];
33           inc(r);
34           q[r]:=y;
35         end;
36       inc(h);
37     end;
38   end;
39 
40 begin
41   readln(n,m);
42   f[0]:=-1;
43   for i:=1 to n do
44   begin
45     readln(s);
46     j:=0;
47     l:=length(s);
48     for k:=1 to l do
49     begin
50       if trie[j,s[k]]=0 then
51       begin
52         inc(t);
53         trie[j,s[k]]:=t;
54       end;
55       j:=trie[j,s[k]];
56     end;
57     can[j]:=true;
58   end;
59   bfs;
60   s0:=1;
61   for i:=1 to m do
62     s0:=s0*26 mod mo;
63   dp[0,0]:=1;
64   for i:=1 to m do
65     for j:=0 to t do
66     begin
67       if can[j] then continue;
68       for c:='A' to 'Z' do
69       begin
70         k:=j;
71         while (k<>-1) do
72         begin
73           if trie[k,c]>0 then
74           begin
75             dp[i,trie[k,c]]:=(dp[i,trie[k,c]]+dp[i-1,j]) mod mo;
76             break;
77           end;
78           k:=f[k];
79         end;
80         if k=-1 then
81           dp[i,0]:=(dp[i,0]+dp[i-1,j]) mod mo;
82       end;
83     end;
84 
85   ss:=0;
86   for i:=0 to t do
87     if not can[i] then ss:=(ss+dp[m,i]) mod mo;
88   writeln((s0+mo-ss) mod mo);
89 end.
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posted on 2015-02-07 10:55  acphile  阅读(117)  评论(0编辑  收藏