Problem p02589 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define ALL(obj) (obj).begin(), (obj).end()
#define SPEED                                                                  \\
  cin.tie(0);                                                                  \\
  ios::sync_with_stdio(false);

template <class T> using PQ = priority_queue<T>;
template <class T> using PQR = priority_queue<T, vector<T>, greater<T>>;

constexpr long long MOD = (long long)1e9 + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433L;

template <class T> vector<T> multivector(size_t N, T init) {
  return vector<T>(N, init);
}
template <class... T> auto multivector(size_t N, T... t) {
  return vector<decltype(multivector(t...))>(N, multivector(t...));
}
template <class T> void corner(bool flg, T hoge) {
  if (flg) {
    cout << hoge << endl;
    exit(0);
  }
}
template <class T, class U>
ostream &operator<<(ostream &o, const map<T, U> &obj) {
  o << "{";
  for (auto &x : obj)
    o << " {" << x.first << " : " << x.second << "}"
      << ",";
  o << " }";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const set<T> &obj) {
  o << "{";
  for (auto itr = obj.begin(); itr != obj.end(); ++itr)
    o << (itr != obj.begin() ? ", " : "") << *itr;
  o << "}";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const multiset<T> &obj) {
  o << "{";
  for (auto itr = obj.begin(); itr != obj.end(); ++itr)
    o << (itr != obj.begin() ? ", " : "") << *itr;
  o << "}";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const vector<T> &obj) {
  o << "{";
  for (int i = 0; i < (int)obj.size(); ++i)
    o << (i > 0 ? ", " : "") << obj[i];
  o << "}";
  return o;
}
template <class T, class U>
ostream &operator<<(ostream &o, const pair<T, U> &obj) {
  o << "{" << obj.first << ", " << obj.second << "}";
  return o;
}
void print(void) { cout << endl; }
template <class Head> void print(Head &&head) {
  cout << head;
  print();
}
template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  cout << head << " ";
  print(forward<Tail>(tail)...);
}
template <class T> void chmax(T &a, const T b) { a = max(a, b); }
template <class T> void chmin(T &a, const T b) { a = min(a, b); }
std::vector<std::string> split(const std::string &str, const char delemiter) {
  std::vector<std::string> res;
  std::stringstream ss(str);
  std::string buffer;
  while (std::getline(ss, buffer, delemiter))
    res.push_back(buffer);
  return res;
}
int msb(int x) { return x ? 31 - __builtin_clz(x) : -1; }
void YN(bool flg) { cout << (flg ? "YES" : "NO") << endl; }
void Yn(bool flg) { cout << (flg ? "Yes" : "No") << endl; }
void yn(bool flg) { cout << (flg ? "yes" : "no") << endl; }

class RollingHash {
private:
  long long base1, base2;
  long long mod1, mod2;
  vector<long long> hash1, hash2, pow1, pow2;

public:
  RollingHash(const string &S)
      : base1(1007), base2(2009), mod1(1000000007), mod2(1000000009) {
    int N = S.size();
    hash1.resize(N + 1, 0);
    hash2.resize(N + 1, 0);
    pow1.resize(N + 1, 1);
    pow2.resize(N + 1, 1);

    for (int i = 1; i <= N; ++i) {
      hash1[i] = ((hash1[i - 1] + S[i - 1]) * base1) % mod1;
      hash2[i] = ((hash2[i - 1] + S[i - 1]) * base2) % mod2;
      pow1[i] = (pow1[i - 1] * base1) % mod1;
      pow2[i] = (pow2[i - 1] * base2) % mod2;
    }
  }

  //[l,r)
  pair<long long, long long> get(int l, int r) {
    long long t1 = ((hash1[r] - hash1[l] * pow1[r - l]) % mod1 + mod1) % mod1;
    long long t2 = ((hash2[r] - hash2[l] * pow2[r - l]) % mod2 + mod2) % mod2;
    return {t1, t2};
  }
};

// verify
// https://atcoder.jp/contests/abc141/tasks/abc141_e

int main() {
  SPEED
  int N;
  cin >> N;
  vector<pair<int, string>> vp(N);
  for (int i = 0; i < N; ++i) {
    string s;
    cin >> s;
    int m = s.size();
    vp[i] = {m, s};
  }
  sort(ALL(vp));
  string U = "";
  for (int i = 0; i < N; ++i) {
    U += vp[i].second;
  }

  RollingHash rh(U);
  map<pair<ll, ll>, vector<int>> mp;
  vector<ll> d(26, 0);

  ll ans = 0;
  vector<int> c(26, 0);
  int sum = 0;
  for (int i = 0; i < N; ++i) {
    string &s = vp[i].second;
    int m = s.size();
    for (int j = 0; j < 26; ++j) {
      c[j] = 0;
    }
    for (int j = 0; j < m; ++j) {
      c[s[j] - 'a']++;
    }
    if (m != 1) {
      for (int j = 0; j < 26; ++j) {
        if (!c[j])
          continue;
        ans += d[j];
      }
    }
    for (int j = m - 1; 0 <= j; --j) {
      int l = sum + j, r = sum + m;
      c[s[j] - 'a']--;
      auto p = rh.get(l, r);
      if (!mp.count(p))
        continue;
      auto v = mp[p];
      for (int k = 0; k < 26; ++k) {
        if (!c[k])
          continue;
        if (v[k])
          ans++;
      }
    }
    if (m == 1) {
      d[s[0] - 'a']++;
    } else {
      auto p = rh.get(sum + 1, sum + m);
      if (!mp.count(p))
        mp[p].resize(26, 0);
      mp[p][s[0] - 'a']++;
    }
    sum += m;
  }
  cout << ans << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define ALL(obj) (obj).begin(), (obj).end()
#define SPEED                                                                  \\
  cin.tie(0);                                                                  \\
  ios::sync_with_stdio(false);

template <class T> using PQ = priority_queue<T>;
template <class T> using PQR = priority_queue<T, vector<T>, greater<T>>;

constexpr long long MOD = (long long)1e9 + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433L;

template <class T> vector<T> multivector(size_t N, T init) {
  return vector<T>(N, init);
}
template <class... T> auto multivector(size_t N, T... t) {
  return vector<decltype(multivector(t...))>(N, multivector(t...));
}
template <class T> void corner(bool flg, T hoge) {
  if (flg) {
    cout << hoge << endl;
    exit(0);
  }
}
template <class T, class U>
ostream &operator<<(ostream &o, const map<T, U> &obj) {
  o << "{";
  for (auto &x : obj)
    o << " {" << x.first << " : " << x.second << "}"
      << ",";
  o << " }";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const set<T> &obj) {
  o << "{";
  for (auto itr = obj.begin(); itr != obj.end(); ++itr)
    o << (itr != obj.begin() ? ", " : "") << *itr;
  o << "}";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const multiset<T> &obj) {
  o << "{";
  for (auto itr = obj.begin(); itr != obj.end(); ++itr)
    o << (itr != obj.begin() ? ", " : "") << *itr;
  o << "}";
  return o;
}
template <class T> ostream &operator<<(ostream &o, const vector<T> &obj) {
  o << "{";
  for (int i = 0; i < (int)obj.size(); ++i)
    o << (i > 0 ? ", " : "") << obj[i];
  o << "}";
  return o;
}
template <class T, class U>
ostream &operator<<(ostream &o, const pair<T, U> &obj) {
  o << "{" << obj.first << ", " << obj.second << "}";
  return o;
}
void print(void) { cout << endl; }
template <class Head> void print(Head &&head) {
  cout << head;
  print();
}
template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  cout << head << " ";
  print(forward<Tail>(tail)...);
}
template <class T> void chmax(T &a, const T b) { a = max(a, b); }
template <class T> void chmin(T &a, const T b) { a = min(a, b); }
std::vector<std::string> split(const std::string &str, const char delemiter) {
  std::vector<std::string> res;
  std::stringstream ss(str);
  std::string buffer;
  while (std::getline(ss, buffer, delemiter))
    res.push_back(buffer);
  return res;
}
int msb(int x) { return x ? 31 - __builtin_clz(x) : -1; }
void YN(bool flg) { cout << (flg ? "YES" : "NO") << endl; }
void Yn(bool flg) { cout << (flg ? "Yes" : "No") << endl; }
void yn(bool flg) { cout << (flg ? "yes" : "no") << endl; }

int main() {
  SPEED
  int N;
  cin >> N;
  vector<pair<int, string>> vp(N);
  for (int i = 0; i < N; ++i) {
    string s;
    cin >> s;
    int m = s.size();
    vp[i] = {m, s};
  }
  sort(ALL(vp));
  unordered_set<string> st;
  ll ans = 0;
  int maxi = 0;
  vector<int> c(26, 0);
  for (int i = 0; i < N; ++i) {
    string &s = vp[i].second;
    int m = s.size();
    for (int i = 0; i < 26; ++i) {
      c[i] = 0;
    }
    for (int i = 0; i < m; ++i) {
      c[s[i] - 'a']++;
    }
    string t = "";
    {
      for (int j = 0; j < 26; ++j) {
        if (!c[j])
          continue;
        t.push_back(char('a' + j));
        if (st.count(t))
          ans++;
        t.pop_back();
      }
    }
    for (int i = m - 1; 0 <= i; --i) {
      t.push_back(s[i]);
      c[s[i] - 'a']--;
      if (t.size() + 1 > m)
        break;
      for (int j = 0; j < 26; ++j) {
        if (!c[j])
          continue;
        t.push_back(char('a' + j));
        if (st.count(t))
          ans++;
        t.pop_back();
      }
    }
    reverse(ALL(s));
    st.insert(s);
    chmax(maxi, m);
  }
  cout << ans << endl;
  return 0;
}