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  • 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
    ",query(str));
        }
        return 0;
    }
    

      

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  • 原文地址:https://www.cnblogs.com/LUO257316/p/3247147.html
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