AC自动机 HDOJ 2222 Keywords Search

题目链接

题意：每个文本串的出现次数

分析：入门题，注意重复的关键字算不同的关键字，还有之前加过的清零。   新模板，加上last跑快一倍

#include <bits/stdc++.h>

struct AC {
    static const int NODE = 10000 * 50 + 5;
    static const int SIZE = 26;
    int ch[NODE][SIZE], fail[NODE], last[NODE];
    int end[NODE];
    int sz;

    void clear() {
        memset (ch[0], 0, sizeof (ch[0]));
        end[0] = 0;
        sz = 1;
    }
    int idx(char ch) {
        return ch - 'a';
    }
    void insert(char *str) {
        int u = 0;
        for (int c, i=0; str[i]; ++i) {
            c = idx (str[i]);
            if (!ch[u][c]) {
                memset (ch[sz], 0, sizeof (ch[sz]));
                end[sz] = 0;
                ch[u][c] = sz++;
            }
            u = ch[u][c];
        }
        end[u]++;
    }
    void build() {
        fail[0] = 0;
        std::queue<int> que;
        for (int c=0; c<SIZE; ++c) {
            int u = ch[0][c];
            if (u) {
                fail[u] = 0;
                last[u] = 0;
                que.push (u);
            }
        }
        while (!que.empty ()) {
            int r = que.front (); que.pop ();
            for (int c=0; c<SIZE; ++c) {
                int u = ch[r][c];
                if (!u) {
                    ch[r][c] = ch[fail[r]][c];
                } else {
                    fail[u] = ch[fail[r]][c];
                    last[u] = end[fail[u]] ? fail[u] : last[fail[u]];
                    que.push (u);
                }
            }
        }
    }
    int query(char *text) {
        int ret = 0, u = 0;
        for (int c, i=0; text[i]; ++i) {
            c = idx (text[i]);
            u = ch[u][c];
            int t = u;
            while (t) {
                ret += end[t];
                end[t] = 0;
                t = last[t];
            }
        }
        return ret;
    }
};
AC ac;
char p[55], t[1000010];

int main(void)    {     //HDOJ 2222 Keywords Search
    int T;  scanf ("%d", &T);
    while (T--) {
        int n;   scanf ("%d", &n);
        ac.clear ();
        for (int i=1; i<=n; ++i)    {
            scanf ("%s", p);    ac.insert (p);
        }
        ac.build ();    scanf ("%s", t);
        printf ("%d\n", ac.query (t));
    }

    return 0;
}