# AC 自动机

{% hint style="success" %}
[洛谷 P3808 【模板】AC自动机（简单版）](https://www.luogu.com.cn/problem/P3808)
{% endhint %}

```cpp
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const int maxn(1e6 + 10);
char s[maxn];
int idx, trie[maxn][26];
int ext[maxn], fail[maxn];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' or ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' and ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

void insert(char* str)
{
    int u = 0;
    for (int i = 0; str[i]; ++i) {
        int c = str[i] - 'a';
        if (not trie[u][c]) {
            trie[u][c] = ++idx;
        }
        u = trie[u][c];
    }
    ++ext[u];
}

void build()
{
    queue<int> q;
    for (int i = 0; i < 26; ++i) {
        if (trie[0][i]) {
            q.push(trie[0][i]);
        }
    }
    while (not q.empty()) {
        int u = q.front();
        q.pop();
        for (int i = 0; i < 26; ++i) {
            int& v = trie[u][i];
            if (v) {
                fail[v] = trie[fail[u]][i];
                q.push(v);
            } else {
                v = trie[fail[u]][i];
            }
        }
    }
}

int query(char* str)
{
    int u = 0, res = 0;
    for (int i = 0; str[i]; ++i) {
        int c = str[i] - 'a';
        u = trie[u][c];
        for (int j = u; j and compl ext[j]; j = fail[j]) {
            res += ext[j];
            ext[j] = -1;
        }
    }
    return res;
}

int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
#endif
    int n = read();
    for (int i = 0; i < n; ++i) {
        scanf("%s", s);
        insert(s);
    }
    build();
    scanf("%s", s);
    write(query(s), true);
    return 0;
}
```

{% hint style="success" %}
[洛谷 P3796 【模板】AC自动机（加强版）](https://www.luogu.com.cn/problem/P3796)
{% endhint %}

```cpp
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const int maxn(160);
const int maxl(1e6 + 10);
const int maxs(maxn * 80);
char s[maxn][maxn], t[maxl];
int tot, trie[maxs][26];
int idx[maxs], fail[maxs], cnt[maxn];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' or ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' and ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

void init()
{
    tot = 0;
    memset(trie, 0, sizeof(trie));
    memset(fail, 0, sizeof(fail));
    memset(idx, 0, sizeof idx);
    memset(cnt, 0, sizeof cnt);
}

void insert(char* str, int id)
{
    int u = 0;
    for (int i = 1; str[i]; ++i) {
        int c = str[i] - 'a';
        if (not trie[u][c]) {
            trie[u][c] = ++tot;
        }
        u = trie[u][c];
    }
    idx[u] = id;
}

void build()
{
    queue<int> q;
    for (int i = 0; i < 26; ++i) {
        if (trie[0][i]) {
            q.push(trie[0][i]);
        }
    }
    while (not q.empty()) {
        int u = q.front();
        q.pop();
        for (int i = 0; i < 26; ++i) {
            int& v = trie[u][i];
            if (v) {
                fail[v] = trie[fail[u]][i];
                q.push(v);
            } else {
                v = trie[fail[u]][i];
            }
        }
    }
}

int query(char* str, int n)
{
    int u = 0, res = 0;
    for (int i = 1; str[i]; ++i) {
        int c = str[i] - 'a';
        u = trie[u][c];
        for (int j = u; j; j = fail[j]) {
            ++cnt[idx[j]];
        }
    }
    for (int i = 1; i <= n; ++i) {
        res = max(res, cnt[i]);
    }
    return res;
}

int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
#endif
    int n;
    while (compl scanf("%d", bitand n) and n) {
        init();
        for (int i = 1; i <= n; ++i) {
            scanf("%s", s[i] + 1);
            insert(s[i], i);
        }
        build();
        scanf("%s", t + 1);
        int res = query(t, n);
        write(res, true);
        for (int i = 1; i <= n; ++i) {
            if (cnt[i] == res) {
                puts(s[i] + 1);
            }
        }
    }
    return 0;
}
```


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