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

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

#define REP(i, m, n) for (int i = (m); i < (int)(n); i++)
#define RREP(i, m, n) for (int i = (int)((n)-1); i >= m; i--)
#define rep(i, n) REP(i, 0, n)
#define rrep(i, n) RREP(i, 0, n)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fi first
#define se second
#define debug(...)                                                             \\
  {                                                                            \\
    cerr << "[L" << __LINE__ << "] ";                                          \\
    _debug(__VA_ARGS__);                                                       \\
  }

template <typename T> string join(const vector<T> &v, string del = ", ") {
  stringstream s;
  for (auto x : v)
    s << del << x;
  return s.str().substr(del.size());
}
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) {
  if (v.size())
    o << "[" << join(v) << "]";
  return o;
}
template <typename T>
ostream &operator<<(ostream &o, const vector<vector<T>> &vv) {
  int l = vv.size();
  if (l) {
    o << endl;
    rep(i, l) o << (i == 0 ? "[ " : ",\\n  ") << vv[i]
                << (i == l - 1 ? " ]" : "");
  }
  return o;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> &p) {
  return o << "(" << p.first << ", " << p.second << ")";
}
inline void _debug() { cerr << endl; }
template <class First, class... Rest>
void _debug(const First &first, const Rest &...rest) {
  cerr << first << " ";
  _debug(rest...);
}

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;

const double PI = (1 * acos(0.0));
const double EPS = 1e-9;
const int INF = 0x3f3f3f3f;
const ll INFL = 0x3f3f3f3f3f3f3f3fLL;
const ll mod = 1e9 + 7;

inline void finput(string filename) { freopen(filename.c_str(), "r", stdin); }

struct RollingHash {
  static const ll base1 = 1009;
  static const ll base2 = 2009;
  static const ll mod1 = 1000000009;
  static const ll mod2 = 1000000007;
  int n;
  vl hash1, hash2, pow1, pow2;
  RollingHash() = default;
  RollingHash(const string &s) {
    n = s.size();
    hash1.assign(n + 1, 0);
    hash2.assign(n + 1, 0);
    pow1.assign(n + 1, 1);
    pow2.assign(n + 1, 1);
    rep(i, n) {
      hash1[i + 1] = (hash1[i] * base1 + s[i]) % mod1;
      hash2[i + 1] = (hash2[i] * base2 + s[i]) % mod2;
      pow1[i + 1] = (pow1[i] * base1) % mod1;
      pow2[i + 1] = (pow2[i] * base2) % mod2;
    }
  }
  // S[l,r)のハッシュ値を返す.
  // O(1)
  inline pair<ll, ll> hash(int l, int r) const {
    ll res1 = (hash1[r] - (hash1[l] * pow1[r - l] % mod1) + mod1) % mod1;
    ll res2 = (hash2[r] - (hash2[l] * pow2[r - l] % mod2) + mod2) % mod2;
    return make_pair(res1, res2);
  }
  inline pair<ll, ll> hash() const { return hash(0, n); }
  // Longest Common Prefix.
  // O(logN)
  inline int calcLCP(const RollingHash &rh, int l1, int r1, int l2,
                     int r2) const {
    int low = 0, high = min(r1 - l1, r2 - l2);
    while (high - low > 1) {
      int mid = (low + high) / 2;
      if (hash(l1, l1 + mid) == hash(l2, l2 + mid)) {
        low = mid;
      } else {
        high = mid;
      }
    }
    return low;
  }
  // hash h1とhash h2を結合.
  pair<ll, ll> concat(pair<ll, ll> h1, pair<ll, ll> h2, int h2len) {
    ll res1 = h1.first * pow1[h2len] + h2.first % mod1;
    ll res2 = h1.second * pow2[h2len] + h2.second % mod2;
    return make_pair(res1, res2);
  }
};

int main() {
  ios_base::sync_with_stdio(0);
  // finput("./input");
  int n;
  cin >> n;
  vector<string> ss(n);
  rep(i, n) cin >> ss[i];

  vector<RollingHash> rhs(n);
  rep(i, n) rhs[i] = RollingHash(ss[i]);
  vi cnt(26);
  vi cnt_total(26);
  map<pll, array<int, 26>> mp;
  rep(i, n) {
    fill(all(cnt), 0);
    cnt[ss[i][0] - 'a'] = 1;
    REP(j, 1, ss[i].size()) {
      auto h = rhs[i].hash(j, ss[i].size());
      rep(c, 26) if (cnt[c])++ mp[h][c];
      cnt[ss[i][j] - 'a'] = 1;
    }
    rep(c, 26) cnt_total[c] += cnt[c];
  }

  ll ans = 0;
  rep(i, n) {
    if (ss[i].size() == 1) {
      ans += cnt_total[ss[i][0] - 'a'];
    } else {
      auto h = rhs[i].hash(1, ss[i].size());
      ans += mp[h][ss[i][0] - 'a'];
    }
    ans--;
  }
  cout << ans << endl;
  return 0;
}

Error: TLE

Fixed submission:

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

#define REP(i, m, n) for (int i = (m); i < (int)(n); i++)
#define RREP(i, m, n) for (int i = (int)((n)-1); i >= m; i--)
#define rep(i, n) REP(i, 0, n)
#define rrep(i, n) RREP(i, 0, n)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fi first
#define se second
#define debug(...)                                                             \\
  {                                                                            \\
    cerr << "[L" << __LINE__ << "] ";                                          \\
    _debug(__VA_ARGS__);                                                       \\
  }

template <typename T> string join(const vector<T> &v, string del = ", ") {
  stringstream s;
  for (auto x : v)
    s << del << x;
  return s.str().substr(del.size());
}
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) {
  if (v.size())
    o << "[" << join(v) << "]";
  return o;
}
template <typename T>
ostream &operator<<(ostream &o, const vector<vector<T>> &vv) {
  int l = vv.size();
  if (l) {
    o << endl;
    rep(i, l) o << (i == 0 ? "[ " : ",\\n  ") << vv[i]
                << (i == l - 1 ? " ]" : "");
  }
  return o;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> &p) {
  return o << "(" << p.first << ", " << p.second << ")";
}
inline void _debug() { cerr << endl; }
template <class First, class... Rest>
void _debug(const First &first, const Rest &...rest) {
  cerr << first << " ";
  _debug(rest...);
}

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;

const double PI = (1 * acos(0.0));
const double EPS = 1e-9;
const int INF = 0x3f3f3f3f;
const ll INFL = 0x3f3f3f3f3f3f3f3fLL;
const ll mod = 1e9 + 7;

inline void finput(string filename) { freopen(filename.c_str(), "r", stdin); }

struct RollingHash {
  static const ll base1 = 1009;
  static const ll base2 = 2009;
  static const ll mod1 = 1000000009;
  static const ll mod2 = 1000000007;
  int n;
  vl hash1, hash2, pow1, pow2;
  RollingHash() = default;
  RollingHash(const string &s) {
    n = s.size();
    hash1.assign(n + 1, 0);
    hash2.assign(n + 1, 0);
    pow1.assign(n + 1, 1);
    pow2.assign(n + 1, 1);
    rep(i, n) {
      hash1[i + 1] = (hash1[i] * base1 + s[i]) % mod1;
      hash2[i + 1] = (hash2[i] * base2 + s[i]) % mod2;
      pow1[i + 1] = (pow1[i] * base1) % mod1;
      pow2[i + 1] = (pow2[i] * base2) % mod2;
    }
  }
  // S[l,r)のハッシュ値を返す.
  // O(1)
  inline pair<ll, ll> hash(int l, int r) const {
    ll res1 = (hash1[r] - (hash1[l] * pow1[r - l] % mod1) + mod1) % mod1;
    ll res2 = (hash2[r] - (hash2[l] * pow2[r - l] % mod2) + mod2) % mod2;
    return make_pair(res1, res2);
  }
  inline pair<ll, ll> hash() const { return hash(0, n); }
  // Longest Common Prefix.
  // O(logN)
  inline int calcLCP(const RollingHash &rh, int l1, int r1, int l2,
                     int r2) const {
    int low = 0, high = min(r1 - l1, r2 - l2);
    while (high - low > 1) {
      int mid = (low + high) / 2;
      if (hash(l1, l1 + mid) == hash(l2, l2 + mid)) {
        low = mid;
      } else {
        high = mid;
      }
    }
    return low;
  }
  // hash h1とhash h2を結合.
  pair<ll, ll> concat(pair<ll, ll> h1, pair<ll, ll> h2, int h2len) {
    ll res1 = h1.first * pow1[h2len] + h2.first % mod1;
    ll res2 = h1.second * pow2[h2len] + h2.second % mod2;
    return make_pair(res1, res2);
  }
};

int main() {
  ios_base::sync_with_stdio(0);
  // finput("./input");
  int n;
  cin >> n;
  vector<string> ss(n);
  rep(i, n) cin >> ss[i];

  vector<RollingHash> rhs(n);
  rep(i, n) rhs[i] = RollingHash(ss[i]);
  vi cnt(26);
  vi cnt_total(26);
  map<pll, int> mp[26];
  rep(i, n) {
    fill(all(cnt), 0);
    cnt[ss[i][0] - 'a'] = 1;
    REP(j, 1, ss[i].size()) {
      auto h = rhs[i].hash(j, ss[i].size());
      rep(c, 26) if (cnt[c])++ mp[c][h];
      cnt[ss[i][j] - 'a'] = 1;
    }
    rep(c, 26) cnt_total[c] += cnt[c];
  }

  ll ans = 0;
  rep(i, n) {
    if (ss[i].size() == 1) {
      ans += cnt_total[ss[i][0] - 'a'];
    } else {
      auto h = rhs[i].hash(1, ss[i].size());
      ans += mp[ss[i][0] - 'a'][h];
    }
    ans--;
  }
  cout << ans << endl;
  return 0;
}