HDU 2222 Keywords Search 【AC自动机模板】

询问有多少个模式串出现在了文本串里面。将模式串插入Trie树中，然后跑一边AC自动机统计一下就哦了。

献上一份模板。

#include <cstdio>
#include <cstring>
#include <queue>
#define MAX_NODE 240005
#define MAX_CHILD 26
using namespace std;

class AC_Automaton {
public:
    int chd[MAX_NODE][MAX_CHILD];
    int fail[MAX_NODE];
    int val[MAX_NODE];
    int ID[128];
    int sz;
    queue<int> q;

    AC_Automaton() {
        for (int i = 0; i < 26; i++)
            ID[i + 'a'] = i;
        Clear();
    }

    void Clear() {
        memset(chd, 0, sizeof (chd));
        memset(fail, 0, sizeof (fail));
        memset(val, 0, sizeof (val));
        sz = 1;
    }

    void Insert(const char *s) {
        int cur = 1;
        for (int i = 0; s[i]; i++) {
            if (!chd[cur][ID[s[i]]]) chd[cur][ID[s[i]]] = ++sz;
            cur = chd[cur][ID[s[i]]];
        }
        val[cur]++;
    }

    void Build_AC() {
        while (!q.empty()) q.pop();
        q.push(1);
        fail[1] = 1;
        while (!q.empty()) {
            int cur = q.front();
            q.pop();
            for (int i = 0; i < MAX_CHILD; i++)
                if (chd[cur][i]) {
                    if (cur == 1) fail[chd[cur][i]] = 1;
                    else {
                        int tmp = fail[cur];
                        while (tmp != 1 && chd[tmp][i] == 0) tmp = fail[tmp];
                        if (chd[tmp][i]) fail[chd[cur][i]] = chd[tmp][i];
                        else fail[chd[cur][i]] = 1;
                    }
                    q.push(chd[cur][i]);
                }
        }
    }

    int Query(const char *s) {
        int ret = 0;
        int cur = 1, tmp;
        for (int i = 0; s[i]; i++) {
            if (chd[cur][ID[s[i]]]) cur = chd[cur][ID[s[i]]];
            else {
                while (cur != 1 && chd[cur][ID[s[i]]] == 0) cur = fail[cur];
                if (chd[cur][ID[s[i]]]) cur = chd[cur][ID[s[i]]];
            }
            tmp = cur;
            while (tmp != 1 && val[tmp] != -1) {
                ret += val[tmp];
                val[tmp] = -1;
                tmp = fail[tmp];
            }
        }
        return ret;
    }
} AC;

char s[60], text[1000001];

int main() {
    int T, n;
    scanf("%d", &T);
    while (T--) {
        scanf("%d", &n);
        AC.Clear();
        while (n--) {
            scanf(" %s", s);
            AC.Insert(s);
        }
        AC.Build_AC();
        scanf(" %s", text);
        printf("%d
", AC.Query(text));
    }
    return 0;
}