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

#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define srep(i, s, t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(), a.end()
#define rrng(a) a.rbegin(), a.rend()
#define isin(x, l, r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)), x.end())
#define snuke srand((unsigned)clock() + (unsigned)time(NULL));
#define show(x) cerr << #x << " = " << x << endl;
#define PQ(T) priority_queue<T, v(T), greater<T>>
#define bn(x) ((1 << x) - 1)
#define dup(x, y) (((x) + (y)-1) / (y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
typedef vector<T> vt;
int getInt() {
  int x;
  scanf("%d", &x);
  return x;
}
template <typename T> istream &operator>>(istream &i, v(T) & v) {
  rep(j, sz(v)) i >> v[j];
  return i;
}
template <typename T> string join(const v(T) & v) {
  stringstream s;
  rep(i, sz(v)) s << ' ' << v[i];
  return s.str().substr(1);
}
template <typename T> ostream &operator<<(ostream &o, const v(T) & v) {
  if (sz(v))
    o << join(v);
  return o;
}
template <typename T1, typename T2>
istream &operator>>(istream &i, pair<T1, T2> &v) {
  return i >> v.fi >> v.se;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> &v) {
  return o << v.fi << "," << v.se;
}
template <typename T> bool mins(T &x, const T &y) {
  if (x > y) {
    x = y;
    return true;
  } else
    return false;
}
template <typename T> bool maxs(T &x, const T &y) {
  if (x < y) {
    x = y;
    return true;
  } else
    return false;
}
template <typename T> ll suma(const v(T) & a) {
  ll res(0);
  for (auto &&x : a)
    res += x;
  return res;
}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame                                                                   \\
  {                                                                            \\
    puts("-1");                                                                \\
    return 0;                                                                  \\
  }
#define yn                                                                     \\
  { puts("Yes"); }                                                             \\
  else {                                                                       \\
    puts("No");                                                                \\
  }
const int MX = 1000005;
typedef v(string) vs;

// rolling hash
// mod pair for hash
const int p1 = 33487;
struct mints {
  template <int mod> struct mint {
    ll x;
    mint(ll x = 0) : x(x) {}
    mint &operator+=(const mint &a) {
      if ((x += a.x) >= mod)
        x -= mod;
      return *this;
    }
    mint &operator-=(const mint &a) {
      if ((x += mod - a.x) >= mod)
        x -= mod;
      return *this;
    }
    mint &operator*=(const mint &a) {
      (x *= a.x) %= mod;
      return *this;
    }
    mint &operator/=(const mint &a) {
      (x *= a.ex(mod - 2).x) %= mod;
      return *this;
    }
    mint operator+(const mint &a) const { return mint(*this) += a; }
    mint operator-(const mint &a) const { return mint(*this) -= a; }
    mint operator*(const mint &a) const { return mint(*this) *= a; }
    mint operator/(const mint &a) const { return mint(*this) /= a; }
    bool operator<(const mint &a) const { return x < a.x; }
    bool operator==(const mint &a) const { return x == a.x; }
    mint ex(ll t) const {
      if (!t)
        return 1;
      mint res = ex(t / 2);
      res *= res;
      return (t & 1) ? res * x : res;
    }
  };
  mint<1011235817> x;
  mint<987654347> y;
  mints(ll x = 0) : x(x), y(x) {}
  mints &operator+=(const mints &a) {
    x += a.x;
    y += a.y;
    return *this;
  }
  mints &operator-=(const mints &a) {
    x -= a.x;
    y -= a.y;
    return *this;
  }
  mints &operator*=(const mints &a) {
    x *= a.x;
    y *= a.y;
    return *this;
  }
  mints &operator/=(const mints &a) {
    x /= a.x;
    y /= a.y;
    return *this;
  }
  mints operator+(const mints &a) const { return mints(*this) += a; }
  mints operator-(const mints &a) const { return mints(*this) -= a; }
  mints operator*(const mints &a) const { return mints(*this) *= a; }
  mints operator/(const mints &a) const { return mints(*this) /= a; }
  bool operator<(const mints &a) const {
    return (x == a.x) ? (y < a.y) : (x < a.x);
  }
  bool operator==(const mints &a) const { return x == a.x && y == a.y; }
  ll get() const { return x.x << 32 | y.x; }
};
ostream &operator<<(ostream &o, const mints &a) {
  o << a.x.x * int(1e9) + a.y.x;
  return o;
}
typedef vector<mints> vm;
//
struct Hash {
  int n;
  vm h, p;
  Hash() {}
  Hash(const string &s) {
    n = sz(s);
    h = p = vm(n + 1);
    p[0] = 1;
    rep(i, n) {
      h[i + 1] = h[i] * p1 + s[i];
      p[i + 1] = p[i] * p1;
    }
  }
  mints get(int l, int r) { return h[r] - h[l] * p[r - l]; }
  bool same(int i, int j, int w) { return get(i, i + w) == get(j, j + w); }
};
//

int main() {
  int n;
  scanf("%d", &n);
  vs s(n);
  cin >> s;
  vvi ss(MX);
  rep(i, n) {
    reverse(rng(s[i]));
    ss[sz(s[i])].pb(i);
  }
  vi is;
  vvi a(n, vi(26));
  v(Hash) h(n);
  rep(i, n) { h[i] = Hash(s[i]); }
  ll ans = 0;
  drep(l, MX) if (l) {
    unordered_map<ll, int> mp;
    for (int i : is) {
      int c = s[i][l - 1] - 'a';
      a[i][c] = 1;
      mints x = h[i].h[l - 1] * p1;
      rep(j, 26) if (a[i][j]) { mp[(x + ('a' + j)).get()]++; }
    }
    for (int i : ss[l]) {
      mints x = h[i].h[l];
      ans += mp[x.get()];
    }
    for (int i : ss[l]) {
      int c = s[i][l - 1] - 'a';
      a[i][c] = 1;
      is.pb(i);
    }
  }
  cout << ans << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define srep(i, s, t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(), a.end()
#define rrng(a) a.rbegin(), a.rend()
#define isin(x, l, r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)), x.end())
#define snuke srand((unsigned)clock() + (unsigned)time(NULL));
#define show(x) cerr << #x << " = " << x << endl;
#define PQ(T) priority_queue<T, v(T), greater<T>>
#define bn(x) ((1 << x) - 1)
#define dup(x, y) (((x) + (y)-1) / (y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
typedef vector<T> vt;
int getInt() {
  int x;
  scanf("%d", &x);
  return x;
}
template <typename T> istream &operator>>(istream &i, v(T) & v) {
  rep(j, sz(v)) i >> v[j];
  return i;
}
template <typename T> string join(const v(T) & v) {
  stringstream s;
  rep(i, sz(v)) s << ' ' << v[i];
  return s.str().substr(1);
}
template <typename T> ostream &operator<<(ostream &o, const v(T) & v) {
  if (sz(v))
    o << join(v);
  return o;
}
template <typename T1, typename T2>
istream &operator>>(istream &i, pair<T1, T2> &v) {
  return i >> v.fi >> v.se;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> &v) {
  return o << v.fi << "," << v.se;
}
template <typename T> bool mins(T &x, const T &y) {
  if (x > y) {
    x = y;
    return true;
  } else
    return false;
}
template <typename T> bool maxs(T &x, const T &y) {
  if (x < y) {
    x = y;
    return true;
  } else
    return false;
}
template <typename T> ll suma(const v(T) & a) {
  ll res(0);
  for (auto &&x : a)
    res += x;
  return res;
}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame                                                                   \\
  {                                                                            \\
    puts("-1");                                                                \\
    return 0;                                                                  \\
  }
#define yn                                                                     \\
  { puts("Yes"); }                                                             \\
  else {                                                                       \\
    puts("No");                                                                \\
  }
const int MX = 1000005;
typedef v(string) vs;

// rolling hash
// mod pair for hash
const int p1 = 33487;
struct mints {
  template <int mod> struct mint {
    ll x;
    mint(ll x = 0) : x(x) {}
    mint &operator+=(const mint &a) {
      if ((x += a.x) >= mod)
        x -= mod;
      return *this;
    }
    mint &operator-=(const mint &a) {
      if ((x += mod - a.x) >= mod)
        x -= mod;
      return *this;
    }
    mint &operator*=(const mint &a) {
      (x *= a.x) %= mod;
      return *this;
    }
    mint &operator/=(const mint &a) {
      (x *= a.ex(mod - 2).x) %= mod;
      return *this;
    }
    mint operator+(const mint &a) const { return mint(*this) += a; }
    mint operator-(const mint &a) const { return mint(*this) -= a; }
    mint operator*(const mint &a) const { return mint(*this) *= a; }
    mint operator/(const mint &a) const { return mint(*this) /= a; }
    bool operator<(const mint &a) const { return x < a.x; }
    bool operator==(const mint &a) const { return x == a.x; }
    mint ex(ll t) const {
      if (!t)
        return 1;
      mint res = ex(t / 2);
      res *= res;
      return (t & 1) ? res * x : res;
    }
  };
  mint<1011235817> x;
  mint<987654347> y;
  mints(ll x = 0) : x(x), y(x) {}
  mints &operator+=(const mints &a) {
    x += a.x;
    y += a.y;
    return *this;
  }
  mints &operator-=(const mints &a) {
    x -= a.x;
    y -= a.y;
    return *this;
  }
  mints &operator*=(const mints &a) {
    x *= a.x;
    y *= a.y;
    return *this;
  }
  mints &operator/=(const mints &a) {
    x /= a.x;
    y /= a.y;
    return *this;
  }
  mints operator+(const mints &a) const { return mints(*this) += a; }
  mints operator-(const mints &a) const { return mints(*this) -= a; }
  mints operator*(const mints &a) const { return mints(*this) *= a; }
  mints operator/(const mints &a) const { return mints(*this) /= a; }
  bool operator<(const mints &a) const {
    return (x == a.x) ? (y < a.y) : (x < a.x);
  }
  bool operator==(const mints &a) const { return x == a.x && y == a.y; }
  ll get() const { return x.x << 32 | y.x; }
};
ostream &operator<<(ostream &o, const mints &a) {
  o << a.x.x * int(1e9) + a.y.x;
  return o;
}
typedef vector<mints> vm;
//
struct Hash {
  int n;
  vm h, p;
  Hash() {}
  Hash(const string &s) {
    n = sz(s);
    h = p = vm(n + 1);
    p[0] = 1;
    rep(i, n) {
      h[i + 1] = h[i] * p1 + s[i];
      p[i + 1] = p[i] * p1;
    }
  }
  mints get(int l, int r) { return h[r] - h[l] * p[r - l]; }
  bool same(int i, int j, int w) { return get(i, i + w) == get(j, j + w); }
};
//

int main() {
  int n;
  scanf("%d", &n);
  vs s(n);
  cin >> s;
  vvi ss(MX);
  rep(i, n) {
    reverse(rng(s[i]));
    ss[sz(s[i])].pb(i);
  }
  vi is;
  vvi a(n, vi(26));
  v(Hash) h(n);
  rep(i, n) { h[i] = Hash(s[i]); }
  ll ans = 0;
  drep(l, MX) if (l) {
    map<mints, int> mp;
    for (int i : is) {
      int c = s[i][l - 1] - 'a';
      a[i][c] = 1;
      mints x = h[i].h[l - 1] * p1;
      rep(j, 26) if (a[i][j]) { mp[x + ('a' + j)]++; }
    }
    for (int i : ss[l]) {
      mints x = h[i].h[l];
      ans += mp[x];
    }
    for (int i : ss[l]) {
      int c = s[i][l - 1] - 'a';
      a[i][c] = 1;
      is.pb(i);
    }
  }
  cout << ans << endl;
  return 0;
}