Problem p02599 (C++)

Buggy submission (status: 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; }

template <class T> class Mo {
  unordered_map<long long, int> mp;
  long long N;
  int bucket;
  vector<pair<int, int>> range;
  vector<int> idx;

public:
  Mo(ll N, const vector<pair<int, int>> &range)
      : N(N), range(range), idx(range.size()), bucket(700) {
    iota(idx.begin(), idx.end(), 0);
    sort(idx.begin(), idx.end(), [&](int a, int b) {
      auto al = range[a].first / bucket;
      auto ar = range[a].second;
      auto bl = range[b].first / bucket;
      auto br = range[b].second;
      return (al != bl) ? (al < bl) : ((al % 2) ? (ar > br) : (ar < br));
    });
  }

  // 参照でvectorを渡したりすると良い
  void solve(const vector<int> &A, vector<int> &cnt, int &sum) {
    int l = 0, r = 0;
    for (int &i : idx) {
      auto &xl = range[i].first;
      auto &xr = range[i].second;

      // 左端を広げる
      while (xl < l) {
        l--;
        extend(l, A, cnt, sum);
      }
      // 右端を広げる
      while (r < xr) {
        r++;
        extend(r, A, cnt, sum);
      }
      // 左端を狭める
      while (l < xl) {
        shrink(l, A, cnt, sum);
        l++;
      }
      // 右端を狭める
      while (xr < r) {
        shrink(r, A, cnt, sum);
        r--;
      }
      mp[xl * N + xr] = sum;
      // print("?",range[i]);
      // print(cnt);
      // print(sum);
      // print(A);
    }
  }

  T &operator[](pair<int, int> p) { return mp[p.first * N + p.second]; }

private:
  // 伸びるとき
  void extend(int k, const vector<int> &A, vector<int> &cnt, int &sum) {
    cnt[A[k]]++;
    if (cnt[A[k]] == 1)
      sum++;
  }

  // 縮むとき
  void shrink(int k, const vector<int> &A, vector<int> &cnt, int &sum) {
    cnt[A[k]]--;
    if (cnt[A[k]] == 0)
      sum--;
  }

  // クエリ結果
  T get(set<int> &sum) { return sum; }
};

int main() {
  int N, Q;
  scanf("%d %d", &N, &Q);
  vector<int> A(N);
  for (int i = 0; i < N; ++i)
    scanf("%d", &A[i]);
  // クエリ区間を列挙
  vector<pair<int, int>> range(Q);
  for (int i = 0; i < Q; ++i) {
    int l, r;
    cin >> l >> r;
    l--, r--;
    range[i] = {l, r};
  }

  // Mo O(N*sqrt(N)*(logN))
  Mo<int> mo(N, range);
  vector<int> cnt(N + 1, 0);
  int sum = 1;
  cnt[A[0]]++;
  mo.solve(A, cnt, sum);
  for (int i = 0; i < Q; ++i) {
    printf("%d\n", mo[range[i]]);
  }

  return 0;
}


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; }

template <class T> class Mo {
  unordered_map<long long, int> mp;
  long long N;
  int bucket;
  vector<pair<int, int>> range;
  vector<int> idx;

public:
  Mo(ll N, const vector<pair<int, int>> &range)
      : N(N), range(range), idx(range.size()), bucket(sqrt(N)) {
    iota(idx.begin(), idx.end(), 0);
    sort(idx.begin(), idx.end(), [&](int a, int b) {
      auto al = range[a].first / bucket;
      auto ar = range[a].second;
      auto bl = range[b].first / bucket;
      auto br = range[b].second;
      return (al != bl) ? (al < bl) : ((al % 2) ? (ar > br) : (ar < br));
    });
  }

  // 参照でvectorを渡したりすると良い
  void solve(const vector<int> &A, vector<int> &cnt, int &sum) {
    int l = 0, r = 0;
    for (int &i : idx) {
      auto &xl = range[i].first;
      auto &xr = range[i].second;

      // 左端を広げる
      while (xl < l) {
        l--;
        extend(l, A, cnt, sum);
      }
      // 右端を広げる
      while (r < xr) {
        r++;
        extend(r, A, cnt, sum);
      }
      // 左端を狭める
      while (l < xl) {
        shrink(l, A, cnt, sum);
        l++;
      }
      // 右端を狭める
      while (xr < r) {
        shrink(r, A, cnt, sum);
        r--;
      }
      mp[xl * N + xr] = sum;
      // print("?",range[i]);
      // print(cnt);
      // print(sum);
      // print(A);
    }
  }

  T &operator[](pair<int, int> p) { return mp[p.first * N + p.second]; }

private:
  // 伸びるとき
  void extend(int k, const vector<int> &A, vector<int> &cnt, int &sum) {
    cnt[A[k]]++;
    if (cnt[A[k]] == 1)
      sum++;
  }

  // 縮むとき
  void shrink(int k, const vector<int> &A, vector<int> &cnt, int &sum) {
    cnt[A[k]]--;
    if (cnt[A[k]] == 0)
      sum--;
  }

  // クエリ結果
  T get(set<int> &sum) { return sum; }
};

int main() {
  int N, Q;
  scanf("%d %d", &N, &Q);
  vector<int> A(N);
  for (int i = 0; i < N; ++i)
    scanf("%d", &A[i]);
  // クエリ区間を列挙
  vector<pair<int, int>> range(Q);
  for (int i = 0; i < Q; ++i) {
    int l, r;
    cin >> l >> r;
    l--, r--;
    range[i] = {l, r};
  }

  // Mo O(N*sqrt(N)*(logN))
  Mo<int> mo(N, range);
  vector<int> cnt(N + 1, 0);
  int sum = 1;
  cnt[A[0]]++;
  mo.solve(A, cnt, sum);
  for (int i = 0; i < Q; ++i) {
    printf("%d\n", mo[range[i]]);
  }

  return 0;
}