【HDOJ】2222 Keywords Search

AC自动机基础题。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <queue>
using namespace std;

#define MAXL  1000005
#define TRIEN 26

char des[MAXL], src[55];

typedef struct Trie {
    int n;
    Trie *fail;
    Trie *next[TRIEN];
    Trie () {
        n = 0;
        fail = NULL;
        memset(next, 0, sizeof(next));
    }
} Trie;

Trie *root;
int n;

void create(char str[]) {
    int i=0, id;
    Trie *p = root, *q;

    while (str[i]) {
        id = str[i] - 'a';
        ++i;
        if (p->next[id] == NULL) {
            q = new Trie();
            p->next[id] = q;
        }
        p = p->next[id];
    }
    p->n++;
}

void build_fail() {
    int i;
    Trie *p, *q;
    queue<Trie *> que;

    for (i=0; i<TRIEN; ++i) {
        if (root->next[i]) {
            root->next[i]->fail = root;
            que.push(root->next[i]);
        }
    }

    while (!que.empty()) {
        p = que.front();
        que.pop();
        for (i=0; i<TRIEN; ++i) {
            if (p->next[i]) {
                q = p->fail;
                while (q != NULL) {
                    if (q->next[i]) {
                        p->next[i]->fail = q->next[i];
                        break;
                    }
                    q = q->fail;
                }
                if (q == NULL)
                    p->next[i]->fail = root;
                que.push(p->next[i]);
            }
        }
    }
}

void search() {
    int i = 0, id;
    Trie *p = root, *tmp;

    n = 0;

    while (des[i]) {
        id = des[i] - 'a';
        ++i;
        while (p->next[id]==NULL && p!=root)
            p = p->fail;
        p = p->next[id];
        if (p == NULL)
            p = root;
        tmp = p;
        while (tmp != root) {
            n += tmp->n;
            tmp->n = 0;
            tmp = tmp->fail;
        }
    }
}

void del(Trie *t) {
    if (t == NULL)
        return ;
    for (int i=0; i<TRIEN; ++i)
        del(t->next[i]);
    free(t);
}

int main() {
    int case_n;

    scanf("%d", &case_n);
    while (case_n--) {
        scanf("%d", &n);
        root = new Trie();
        while (n--) {
            scanf("%s", src);
            create(src);
        }
        scanf("%s", des);
        build_fail();
        search();
        printf("%d
", n);
        del(root);
    }

    return 0;
}