Wireless Password - HDU 2825（ac自动机+状态压缩）

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<string.h>
#include<queue>
using namespace std;

const int MAXN = 107;
const int MaxSon = 26;
const int Mod = 20090717;
const int oo = 1e9+7;

struct Ac_Trie
{
    int next[MAXN][MaxSon];
    int Fail[MAXN], End[MAXN];
    int cnt, root;

    int newnode()
    {
        for(int i=0; i<MaxSon; i++)
            next[cnt][i] = -1;
        Fail[cnt] = End[cnt] = false;

        return cnt++;
    }
    void InIt()
    {
        cnt = 0;
        root = newnode();
    }

    void Insert(char s[], int t)
    {
        int now = root;

        for(int i=0; s[i]; i++)
        {
            int k = s[i]-‘a‘;

            if(next[now][k] == -1)
                next[now][k] = newnode();
            now = next[now][k];
        }

        End[now] = 1<<t;
    }
    void GetFial()
    {
        queue<int>Q;
        int now = root;

        for(int i=0; i<MaxSon; i++)
        {
            if(next[now][i] == -1)
                next[now][i] = root;
            else
            {
                Fail[next[now][i]] = root;
                Q.push(next[now][i]);
            }
        }

        while(Q.size())
        {
            now = Q.front();
            Q.pop();

            for(int i=0; i<MaxSon; i++)
            {
                if(next[now][i] == -1)
                    next[now][i] = next[Fail[now]][i];
                else
                {
                    Fail[next[now][i]] = next[Fail[now]][i];
                    Q.push(next[now][i]);
                }
            }

            End[now] |= End[Fail[now]];
        }
    }
};
Ac_Trie ac;

int Find(int i)
{
    int k=0;

    while(i)
    {
        if(i % 2)
            k++;
        i /= 2;
    }

    return k;
}

int main()
{
    int N, M, K;

    int sum[1024] ={0};

    for(int i=0; i<1024; i++)
        sum[i] = Find(i);

    while(scanf("%d%d%d", &N, &M, &K), N+M+K)
    {
        char s[MAXN];
        ac.InIt();

        for(int i=0; i<M; i++)
        {
            scanf("%s", s);
            ac.Insert(s, i);
        }

        ac.GetFial();

        int dp[2][MAXN][1024] = {0}, op=0, Len = 1<<M;
        dp[1][0][0] = 1;

        while(N--)
        {
            memset(dp[op], 0, sizeof(dp[op]));

            for(int i=0; i<ac.cnt; i++)
            for(int k=0; k<Len; k++)
            {///把k放中间优化一下...否则超时
                if(dp[op^1][i][k] == 0)
                    continue;

                for(int j=0; j<MaxSon; j++)
                {
                    (dp[op][ac.next[i][j]][k|ac.End[i]] += dp[op^1][i][k])%=Mod;
                }
            }

            op ^= 1;
        }

        int ans = 0;

        for(int i=0; i<ac.cnt; i++)
        for(int j=0; j<Len; j++)
        {
            if(sum[j] >= K || sum[ac.End[i]|j] >= K)
            {
                ans += dp[op^1][i][j];
                ans %= Mod;
            }
        }

        printf("%d\n", ans);
    }

    return 0;
}