HDU 2825 Wireless Password（AC自动机+DP）

问至少包含给定的\(k\)个字符串且长度为\(n\)的字符串个数

设\(dp[i][j][k]\)表示长度为\(i\)匹配到AC自动机的节点\(j\)包含了\(k\)状态的答案
\(dp[0][0][0]=1\)

#include
using namespace std;
typedef long long ll;
const int mod=20090717;
const int maxn=110;
int dp[30][maxn][1<<10],n,m,k;
char s[20];
struct Trie{
    int next[maxn][26], fail[maxn], end[maxn];
    int last[maxn];
    int root, L;
    int newnode(){
        for (int i = 0; i < 26; i++)
            next[L][i] = -1;
        fail[L]=last[L]=end[L]=0;
        return L++;
    }
    void init(){
        L = 0;
        root = newnode();
    }
    void insert(char buf[],int k){
        int len = strlen(buf);
        int now = root;
        for(int i=0;iQ;
        fail[root]=root;
        for(int i = 0;i < 26;i++){
            if(next[root][i]==-1)
                next[root][i]=root;
            else{
                fail[next[root][i]] = root;
                Q.push(next[root][i]);
            }
        }
        while(!Q.empty()){
            int now = Q.front();
            Q.pop();
            end[now]|=end[fail[now]]; ///!!!! AC 
            for(int i = 0;i < 26;i++){
                if(next[now][i] == -1) 
                    next[now][i] = next[fail[now]][i];
                else{
                    int son=next[now][i];
                    fail[son]=next[fail[now]][i];
                    last[son]=end[fail[son]]?fail[son]:last[fail[son]];
                    Q.push(next[now][i]); 
                }  
            }
        }
    }
    int cal(){
        memset(dp,0,sizeof(dp));
        dp[0][0][0]=1;
        for(int i=0;i=k){
                    ans+=dp[n][i][j];
                    ans%=mod;
                }
            }
        }
        return ans;
    }
}ac;

int main(){
    while(scanf("%d%d%d",&n,&m,&k)){
        if(n==0&&m==0&&k==0)break;
        ac.init();
        for(int i=0;i