Problem p01973 (C++) — buggy submission, verdict: Memory Limit Exceeded

// g++ -std=c++11 a.cpp
#include <algorithm>
#include <assert.h>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <typeinfo>
#include <utility>
#include <vector>
#define loop(i, a, b) for (int i = a; i < b; i++)
#define rep(i, a) loop(i, 0, a)
#define pb push_back
#define all(in) in.begin(), in.end()
#define shosu(x) fixed << setprecision(x)
using namespace std;
// kaewasuretyuui
typedef long long ll;
// #define int ll
typedef int Def;
typedef pair<Def, Def> pii;
typedef vector<Def> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<Def, pii> pip;
typedef vector<pip> vip;
#define mt make_tuple
typedef tuple<int, int, int> tp;
typedef vector<tp> vt;
template <typename A, typename B> bool cmin(A &a, const B &b) {
  return a > b ? (a = b, true) : false;
}
template <typename A, typename B> bool cmax(A &a, const B &b) {
  return a < b ? (a = b, true) : false;
}
// template<class C>constexpr int size(const C &c){return (int)c.size();}
// template<class T,size_t N> constexpr int size(const T
// (&xs)[N])noexcept{return (int)N;}
const double PI = acos(-1);
const double EPS = 1e-7;
Def inf = sizeof(Def) == sizeof(long long) ? 2e18 : 1e9 + 10;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
#define MAX 26
#define OFFSET 'a'
struct Node {
  int nxt[MAX + 1]; // 次のalphabeteのノード番号
  int exist;        // 子ども以下に存在する文字列の数の合計
  vi accept;        // その文字列id
  Node() : exist(0) { memset(nxt, -1, sizeof(nxt)); }
};
struct Trie {
  vector<Node> nodes;
  int root;
  Trie() : root(0) { nodes.push_back(Node()); }

  void update_direct(int node, int id) { nodes[node].accept.push_back(id); }
  void update_child(int node, int child, int id) { ++nodes[node].exist; }
  void add(const string &str, int str_index, int node_index, int id) {
    if (str_index == str.size())
      update_direct(node_index, id);
    else {
      const int c = str[str_index] - OFFSET;
      if (nodes[node_index].nxt[c] == -1) {
        nodes[node_index].nxt[c] = (int)nodes.size();
        nodes.push_back(Node());
      }
      add(str, str_index + 1, nodes[node_index].nxt[c], id);
      update_child(node_index, nodes[node_index].nxt[c], id);
    }
  }
  void add(const string &str, int id) { add(str, 0, 0, id); }
  void add(const string &str) { add(str, nodes[0].exist); }
  int size() { return (nodes[0].exist); }
  int nodesize() { return ((int)nodes.size()); }
};
struct Aho_Corasick : Trie {
  static const int FAIL = MAX;
  vi correct;
  Aho_Corasick() : Trie() {}

  void build() {
    correct.resize(nodes.size());
    rep(i, nodes.size()) correct[i] = (int)nodes[i].accept.size();

    queue<int> que;
    rep(i, MAX + 1) {
      if (~nodes[0].nxt[i]) {
        nodes[nodes[0].nxt[i]].nxt[FAIL] = 0;
        que.emplace(nodes[0].nxt[i]);
      } else
        nodes[0].nxt[i] = 0;
    }
    while (!que.empty()) {
      Node &now = nodes[que.front()];
      correct[que.front()] += correct[now.nxt[FAIL]];
      que.pop();
      rep(i, MAX) {
        if (now.nxt[i] == -1)
          continue;
        int fail = now.nxt[FAIL];
        while (nodes[fail].nxt[i] == -1) {
          fail = nodes[fail].nxt[FAIL];
        }
        nodes[now.nxt[i]].nxt[FAIL] = nodes[fail].nxt[i];

        auto &u = nodes[now.nxt[i]].accept;
        auto &v = nodes[nodes[fail].nxt[i]].accept;
        vi accept;
        set_union(all(u), all(v), back_inserter(accept));
        u = accept;
        que.emplace(now.nxt[i]);
      }
    }
  }
  int match(const string &str, vi &result, int now = 0) {
    result.assign(size(), 0);
    int count = 0;
    for (auto &c : str) {
      while (nodes[now].nxt[c - OFFSET] == -1)
        now = nodes[now].nxt[FAIL];
      now = nodes[now].nxt[c - OFFSET];
      count += correct[now];
      for (auto &v : nodes[now].accept)
        result[v]++;
    }
    return count;
  }
  int next(int now, char c) {
    while (nodes[now].nxt[c - OFFSET] == -1)
      now = nodes[now].nxt[FAIL];
    return nodes[now].nxt[c - OFFSET];
  }
};
int main() {
  string s;
  cin >> s;
  int n;
  cin >> n;
  vs p(n);
  rep(i, n) cin >> p[i];
  Aho_Corasick ac;
  rep(i, n) ac.add(p[i]);
  ac.build();
  int now = ac.root;
  vp dp;
  rep(i, s.size()) {
    now = ac.next(now, s[i]);
    int ma = -1;
    for (int j : ac.nodes[now].accept) {
      ma = max(ma, i + 1 - (int)p[j].size());
      //			dp.pb({i+1,i+1-p[j].size()});
    }
    if (ma != -1)
      dp.pb({i + 1, ma});
    //			if(dp[i+1-p[j].size()]>=0)(dp[i+1]+=dp[i+1-p[j].size()])%=1000000007;
  }
  //	rep(i,dp.size())cout<<dp[i].first<<" "<<dp[i].second<<endl;
  sort(all(dp));
  int out = 0;
  int last = -inf;
  rep(i, dp.size()) {
    int a = dp[i].second, b = dp[i].first;
    if (last < a) {
      last = b - 1;
      out++;
    }
  }
  cout << out << endl;
}


Error: MLE

Fixed submission:

// g++ -std=c++11 a.cpp
#include <algorithm>
#include <assert.h>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <typeinfo>
#include <utility>
#include <vector>
#define loop(i, a, b) for (int i = a; i < b; i++)
#define rep(i, a) loop(i, 0, a)
#define pb push_back
#define all(in) in.begin(), in.end()
#define shosu(x) fixed << setprecision(x)
using namespace std;
// kaewasuretyuui
typedef long long ll;
// #define int ll
typedef int Def;
typedef pair<Def, Def> pii;
typedef vector<Def> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<Def, pii> pip;
typedef vector<pip> vip;
#define mt make_tuple
typedef tuple<int, int, int> tp;
typedef vector<tp> vt;
template <typename A, typename B> bool cmin(A &a, const B &b) {
  return a > b ? (a = b, true) : false;
}
template <typename A, typename B> bool cmax(A &a, const B &b) {
  return a < b ? (a = b, true) : false;
}
// template<class C>constexpr int size(const C &c){return (int)c.size();}
// template<class T,size_t N> constexpr int size(const T
// (&xs)[N])noexcept{return (int)N;}
const double PI = acos(-1);
const double EPS = 1e-7;
Def inf = sizeof(Def) == sizeof(long long) ? 2e18 : 1e9 + 10;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
#define MAX 26
#define OFFSET 'a'
struct Node {
  int nxt[MAX + 1]; // 次のalphabeteのノード番号
  int exist;        // 子ども以下に存在する文字列の数の合計
  vi accept;        // その文字列id
  Node() : exist(0) { memset(nxt, -1, sizeof(nxt)); }
};
struct Trie {
  vector<Node> nodes;
  int root;
  Trie() : root(0) { nodes.push_back(Node()); }

  void update_direct(int node, int id) { nodes[node].accept.push_back(id); }
  void update_child(int node, int child, int id) { ++nodes[node].exist; }
  void add(const string &str, int str_index, int node_index, int id) {
    if (str_index == str.size())
      update_direct(node_index, id);
    else {
      const int c = str[str_index] - OFFSET;
      if (nodes[node_index].nxt[c] == -1) {
        nodes[node_index].nxt[c] = (int)nodes.size();
        nodes.push_back(Node());
      }
      add(str, str_index + 1, nodes[node_index].nxt[c], id);
      update_child(node_index, nodes[node_index].nxt[c], id);
    }
  }
  void add(const string &str, int id) { add(str, 0, 0, id); }
  void add(const string &str) { add(str, nodes[0].exist); }
  int size() { return (nodes[0].exist); }
  int nodesize() { return ((int)nodes.size()); }
};
struct Aho_Corasick : Trie {
  static const int FAIL = MAX;
  vi correct;
  Aho_Corasick() : Trie() {}

  void build() {
    correct.resize(nodes.size());
    rep(i, nodes.size()) correct[i] = (int)nodes[i].accept.size();

    queue<int> que;
    rep(i, MAX + 1) {
      if (~nodes[0].nxt[i]) {
        nodes[nodes[0].nxt[i]].nxt[FAIL] = 0;
        que.emplace(nodes[0].nxt[i]);
      } else
        nodes[0].nxt[i] = 0;
    }
    while (!que.empty()) {
      Node &now = nodes[que.front()];
      correct[que.front()] += correct[now.nxt[FAIL]];
      que.pop();
      rep(i, MAX) {
        if (now.nxt[i] == -1)
          continue;
        int fail = now.nxt[FAIL];
        while (nodes[fail].nxt[i] == -1) {
          fail = nodes[fail].nxt[FAIL];
        }
        nodes[now.nxt[i]].nxt[FAIL] = nodes[fail].nxt[i];

        auto &u = nodes[now.nxt[i]].accept;
        auto &v = nodes[nodes[fail].nxt[i]].accept;
        vi accept;
        set_union(all(u), all(v), back_inserter(accept));
        u = accept;
        que.emplace(now.nxt[i]);
      }
    }
  }
  int match(const string &str, vi &result, int now = 0) {
    result.assign(size(), 0);
    int count = 0;
    for (auto &c : str) {
      while (nodes[now].nxt[c - OFFSET] == -1)
        now = nodes[now].nxt[FAIL];
      now = nodes[now].nxt[c - OFFSET];
      count += correct[now];
      for (auto &v : nodes[now].accept)
        result[v]++;
    }
    return count;
  }
  int next(int now, char c) {
    while (nodes[now].nxt[c - OFFSET] == -1)
      now = nodes[now].nxt[FAIL];
    return nodes[now].nxt[c - OFFSET];
  }
};
int main() {
  string s;
  cin >> s;
  int n;
  cin >> n;
  vs p(n);
  rep(i, n) cin >> p[i];
  Aho_Corasick ac;
  rep(i, n) ac.add(p[i]);
  ac.build();
  int now = ac.root;
  vp dp;
  rep(i, s.size()) {
    now = ac.next(now, s[i]);
    for (int j : ac.nodes[now].accept) {
      dp.pb({i + 1, i + 1 - p[j].size()});
    }
    //			if(dp[i+1-p[j].size()]>=0)(dp[i+1]+=dp[i+1-p[j].size()])%=1000000007;
  }
  //	rep(i,dp.size())cout<<dp[i].first<<" "<<dp[i].second<<endl;
  sort(all(dp));
  int out = 0;
  int last = -inf;
  rep(i, dp.size()) {
    int a = dp[i].second, b = dp[i].first;
    if (last < a) {
      last = b - 1;
      out++;
    }
  }
  cout << out << endl;
}