【HDU】2825 Wireless Password

#include<cstdio>
#include<cstring>
#include<queue>
#define MAXN 110
#define MAXM 26
#define MAXL (1<<10)
#define MOD 20090717
using namespace std;
char str[MAXN];
int size, digit[MAXL], dp[30][MAXN][MAXL];
struct node {
    int fail, end, next[MAXM];
    void Init() {
        fail = end = 0;
        memset(next, 0, sizeof(next));
    }
};
node tree[MAXN];
inline int GET(char ch) {
    return ch - 'a';
}
void Insert(char *s, int pos) {
    int now, t;
    for (now = 0; *s; s++) {
        t = GET(*s);
        if (!tree[now].next[t]) {
            tree[++size].Init();
            tree[now].next[t] = size;
        }
        now = tree[now].next[t];
    }
    tree[now].end |= (1 << pos);
}
void BFS() {
    int now, i, p;
    queue<int> q;
    q.push(0);
    while (!q.empty()) {
        now = q.front();
        q.pop();
        for (i = 0; i < MAXM; i++) {
            if (tree[now].next[i]) {
                p = tree[now].next[i];
                q.push(p);
                if (now)
                    tree[p].fail = tree[tree[now].fail].next[i];
                tree[p].end |= tree[tree[p].fail].end;
            } else
                tree[now].next[i] = tree[tree[now].fail].next[i];
        }
    }
}
void Init() {
    int i, k;
    for (i = 0; i < MAXL; i++) {
        digit[i] = 0;
        for (k = i; k; k >>= 1) {
            if (k & 1)
                digit[i]++;
        }
    }
}
void DoIt(int n, int m, int t) {
    int i, j, k, l, p, ans;
    for (i = 1; i <= n; i++) {
        for (j = 0; j <= size; j++)
            memset(dp[i][j], 0, sizeof(int) * (1 << m));
    }
    dp[0][0][0] = 1;
    for (i = 1; i <= n; i++) {
        for (j = 0; j <= size; j++) {
            for (k = 0; k < (1 << m); k++) {
                if (dp[i - 1][j][k] && (tree[j].end & k) == tree[j].end) {
                    for (l = 0; l < MAXM; l++) {
                        p = tree[j].next[l];
                        dp[i][p][k | tree[p].end] += dp[i - 1][j][k];
                        if (dp[i][p][k | tree[p].end] >= MOD)
                            dp[i][p][k | tree[p].end] %= MOD;
                    }
                }
            }
        }
    }
    for (j = ans = 0; j <= size; j++) {
        for (k = 0; k < (1 << m); k++) {
            if (digit[k] >= t) {
                ans += dp[n][j][k];
                if (ans >= MOD)
                    ans %= MOD;
            }
        }
    }
    printf("%d\n", ans);
}
int main() {
    int n, m, k, i;
    Init();
    while (scanf("%d%d%d", &n, &m, &k), n) {
        tree[0].Init();
        for (size = i = 0; i < m; i++) {
            scanf(" %s", str);
            Insert(str, i);
        }
        BFS();
        DoIt(n, m, k);
    }
    return 0;
}