1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
| #include <cstdio>
#include <queue>
#include <cstring>
using namespace std;
const int N = 6e3 + 10, M = 110, mod = 1e4 + 7;
char s[N];
int n, m, f[N][M];
int idx, cnt[N], nxt[N], tr[N][26];
int binpow (int b, int k)
{
int res = 1;
while (k)
{
if (k & 1)
res = res * b % mod;
b = b * b % mod;
k >>= 1;
}
return res;
}
void insert (int len, char *str)
{
int p = 0;
for (int i = 1; i <= len; i++)
{
int &t = tr[p][str[i] - 'A'];
!t && (t = ++idx);
p = t;
}
cnt[p]++;
}
void build ()
{
queue <int> q;
for (int i = 0; i < 26; i++)
tr[0][i] && (q.push(tr[0][i]), 0);
while (!q.empty())
{
int t = q.front();
q.pop();
for (int i = 0; i < 26; i++)
{
int &p = tr[t][i];
if (!p)
p = tr[nxt[t]][i];
else
{
nxt[p] = tr[nxt[t]][i];
q.push(p);
}
}
cnt[t] += cnt[nxt[t]];
}
}
int main ()
{
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; i++)
{
scanf("%s", s + 1);
insert(strlen(s + 1), s);
}
build();
f[0][0] = 1;
for (int k = 0; k < m; k++)
for (int i = 0; i <= idx; i++)
for (int j = 0; j < 26; j++)
if (!cnt[tr[i][j]])
(f[tr[i][j]][k + 1] += f[i][k]) %= mod;
int res = binpow(26, m);
for (int i = 0; i <= idx; i++)
(res -= f[i][m]) %= mod;
printf("%d", (res + mod) % mod);
return 0;
}
|