HDU2222Keywords Search AC_自动机

http://blog.csdn.net/niushuai666/article/details/7002823

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
struct node{
    int count;
    node *next[26],*fail;
    void Node(){
        count = 0;fail = NULL;
        memset(next,NULL,sizeof(next));
    }
}arr[300005],*que[500005];
char str[1000006];
int cnt = 0;
void insert(char *str){
    node *p = &arr[0];
    while( *str ){
        int k = *str++ - 'a';
        if( !p->next[k] ){
            arr[++cnt].Node();
            p->next[k] = &arr[cnt];
        }
        p = p->next[k];
    }
    p->count++;
}

void build_AC(){
    node *root = &arr[0],*tmp,*p;
    int head = 0,tail = 0;
    for(int i = 0; i < 26; i++){
        if(!root->next[i])continue;
        root->next[i]->fail = root;
        que[head++] = root->next[i];
    }
    while( head != tail){
        tmp = que[tail++];
        for(int i = 0; i < 26 ; i++){
            if( tmp->next[i] ){
                p = tmp->fail;
                while( p ){
                    if( p->next[i] ){
                        tmp->next[i]->fail = p->next[i];
                        break;
                    }
                    p = p->fail;
                }
                if(!p)tmp->next[i]->fail = root;
                que[head++] = tmp->next[i];
            }
        }
    }
}
int query(char *str){
    node *root = &arr[0],*p = &arr[0];
    int ans= 0;
    while( *str ){
        int k = *str++ - 'a';
        while( !p->next[k] && p != root) p = p->fail;
        p = p->next[k];
        p = p ? p : root;
        node *tmp = p;
        while( tmp != root && tmp->count != -1){
            ans += tmp->count;
            tmp->count = -1;
            tmp = tmp->fail;
        }
    }
    return ans;
}
int main(){
   // freopen("in.txt","r",stdin);
    int t,n;
    char ch[60];
    scanf("%d",&t);
    while( t-- ){
        scanf("%d",&n);
        arr[cnt = 0].Node();
        while( n-- ){
            scanf("%s",ch);
            insert(ch);
        }
        build_AC();
        scanf("%s",str);
        printf("%d\n",query(str));
    }
    return 0;
}