HDU 2825 Wireless Password(AC自动机+DP)

题目链接

做题，

 #include <cstdio>
 #include <string>
 #include <cstring>
 using namespace std;
 #define MOD 20090717
 int trie[][];
 int o[];
 int fail[];
 int que[];
 int dp[][][];
 int flag[];
 int t;
 void CL()
 {
     memset(trie,-,sizeof(trie));
     memset(dp,,sizeof(dp));
     memset(o,,sizeof(o));
     t = ;
 }
 void insert(char *s,int num)
 {
     int root,i,len;
     len = strlen(s);
     root = ;
     for(i = ;i < len;i ++)
     {
         if(trie[root][s[i]-'a'] == -)
         trie[root][s[i]-'a'] = t ++;
         root = trie[root][s[i]-'a'];
     }
     o[root] |= <<num;
 }
 void build_ac()
 {
     int head,tail,front,i;
     head = tail = ;
     for(i = ;i < ;i ++)
     {
         if(trie[][i] != -)
         {
             fail[trie[][i]] = ;
             que[tail++] = trie[][i];
         }
         else
         {
             trie[][i] = ;
         }
     }
     while(head != tail)
     {
         front = que[head++];
         o[front] |= o[fail[front]];
         for(i = ;i < ;i ++)
         {
             if(trie[front][i] != -)
             {
                 que[tail++] = trie[front][i];
                 fail[trie[front][i]] = trie[fail[front]][i];
             }
             else
             {
                 trie[front][i] = trie[fail[front]][i];
             }
         }
     }
 }
 int main()
 {
     int n,m,r,k,i,j,u,x,y;
     char str[];
     for(i = ;i < ;i ++)
     {
         for(j = ;j < ;j ++)
         {
             if(i&(<<j)) flag[i] ++;
         }
     }
     while(scanf("%d%d%d",&n,&m,&r)!=EOF)
     {
         if(n == &&m == &&r == ) break;
         CL();
         for(i = ;i < m;i ++)
         {
             scanf("%s",str);
             insert(str,i);
         }
         build_ac();
         dp[][][] = ;
         x = ;y = ;
         for(i = ;i < n;i ++)
         {
             memset(dp[y],,sizeof(dp[y]));
             for(j = ;j < t;j ++)
             {
                 for(k = ;k < (<<m);k ++)
                 {
                     if(dp[x][j][k] == ) continue;
                     for(u = ;u < ;u ++)
                     {
                         int temp =  trie[j][u];
                         dp[y][temp][k|o[temp]] += dp[x][j][k];
                         if(dp[y][temp][k|o[temp]] >= MOD)
                         dp[y][temp][k|o[temp]] -= MOD;
                     }
                 }
             }
             swap(x,y);
         }
         int ans = ;
         for(i = ;i < t;i ++)
         {
             for(j = ;j < (<<m);j ++)
             {
                 if(flag[j] >= r)
                 ans = (ans + dp[x][i][j])%MOD;
             }
         }
         printf("%d\n",ans);
     }
     return ;
 }

找找手感。