洛谷-P3796-【模板】AC自动机（加强版）

题目传送门

-------------------------------------- 过年在家无聊补一下这周做的几道AC自动机的模板题

sol:AC自动机，在fail边的基础上再加一个last边，指向真正有效的节点，跳fail边改成跳last边来跳过无效点。

• AC自动机

  #include <bits/stdc++.h>
  using namespace std;
  typedef long long LL;
  typedef pair<int, int> PII;
  const int MAXN = 11000;
  struct Trie {
      int son[MAXN][26], fail[MAXN], last[MAXN];
      int cnt[MAXN], inde[MAXN]; int tot, root, _max;
      vector<int> vec; string str[160];
      int add_node() {
          memset(son[tot], -1, sizeof(son[tot]));
          cnt[tot] = 0; inde[tot] = -1;
          return tot ++;
      }
      void init() {
          tot = _max = 0;
          root = add_node();
      }
      void insert(char* s, int id) {
          int p = root;
          for (int i = 0; s[i]; i++) {
              int index = s[i] - 'a';
              if (son[p][index] == -1)
                  son[p][index] = add_node();
              p = son[p][index];
          }
          inde[p] = id;
          str[id] = s;
      }
      void build() {
          queue<int> que;
          fail[root] = last[root] = root;
          for (int i = 0; i < 26; i++) {
              if (son[root][i] == -1) son[root][i] = root;
              else {
                  fail[son[root][i]] = root;
                  last[son[root][i]] = root;
                  que.push(son[root][i]);
              }
          }
          while (!que.empty()) {
              int p = que.front(); que.pop();
              for (int i = 0; i < 26; i++) {
                  if (son[p][i] == -1) son[p][i] = son[fail[p]][i];
                  else {
                      fail[son[p][i]] = son[fail[p]][i];
                      if (inde[son[fail[p]][i]] != -1)
                          last[son[p][i]] = son[fail[p]][i];
                      else
                          last[son[p][i]] = son[last[p]][i];
                      que.push(son[p][i]);
                  }
              }
          }
      }
      void slove(char* s) {
          int p = root;
          for (int i = 0; s[i]; i++) {
              int index = s[i] - 'a';
              p = son[p][index];
              for (int tmp = p; tmp != root; tmp = last[tmp]) {
                  if (inde[tmp] == -1) continue;
                  cnt[tmp] ++;
                  if (cnt[tmp] > _max) {
                      _max = cnt[tmp];
                      vec.clear();
                      vec.push_back(inde[tmp]);
                  } else if (cnt[tmp] == _max) {
                      vec.push_back(inde[tmp]);
                  }
              }
          }
      }
      void output() {
          printf("%d\n", _max);
          sort(vec.begin(), vec.end());
          for (int i = 0; i < vec.size(); i++)
              cout << str[vec[i]] << endl;
      }
  } ac;
  char s[1000010];
  int main() {
      int n;
      while (scanf("%d", &n) && n) {
          ac.init();
          for (int i = 1; i <= n; i++) {
              scanf("%s", s);
              ac.insert(s, i);
          }
          ac.build(); scanf("%s", s);
          ac.slove(s); ac.output();
      }
      return 0;
  }