AC自动机

下面的代码能过 洛谷P3808 【模板】AC自动机（简单版）。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>

using namespace std;

#define re register
#define rep(i, x, y) for (register int i = x; i <= y; ++i)
#define repd(i, x, y) for (register int i = x; i >= y; --i)

const int maxn = 1e6 + 5;

int n, ans = 0;
char str[maxn];

struct AC_automata {
    #define SIGMA_SIZE 26
    int f[maxn], ch[maxn][SIGMA_SIZE], val[maxn], sz, last[maxn];
    inline int idx(char c) { return c - 'a'; }
    void init() {
        sz = 0;
    }
    void insert(char *t) {
        int L = strlen(t), o = 0;
        rep(i, 0, L - 1) {
            if (ch[o][idx(t[i])]) o = ch[o][idx(t[i])];
            else o = ch[o][idx(t[i])] = ++sz;
        }
        val[o]++;
    }
    void getfail() {
        queue<int> q;
        f[0] = 0;
        rep(i, 0, SIGMA_SIZE - 1) {
            re int u = ch[0][i];
            if (u) { q.push(u); f[u] = 0; last[u] = 0; }
        }
        while (!q.empty()) {
            re int r = q.front(); q.pop();
            rep(i, 0, SIGMA_SIZE - 1) {
                re int u = ch[r][i];
                if (!u) { ch[r][i] = ch[f[r]][i]; continue; }
                q.push(u);
                re int v = f[r];
                while (v && !ch[v][i]) v = f[v];
                f[u] = ch[v][i];
                last[u] = val[f[u]] ? f[u] : last[f[u]];
            }
        }
    }
    void print(int o) {
        if (o) {
            ans += val[o];
            val[o] = 0;
            print(last[o]);
        }
    }
    void find(char *T) {
        re int L = strlen(T), o = 0;
        rep(i, 0, L-1) {
            re int c = idx(T[i]);
            o = ch[o][c];
            if (val[o]) print(o);
            else if (last[o]) print(last[o]);
        }
    }
} ac;

int main() {
    scanf("%d", &n);

    ac.init();

    rep(i, 1, n) {
        scanf("%s", str);
        ac.insert(str);
    }

    scanf("%s", str);

    ac.getfail();
    ac.find(str);

    printf("%d", ans);
    return 0;
}