Problem p02599 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <array>
#include <assert.h>
#include <bitset>
#include <climits>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#define LEN(x) (long long)(x.size())
#define FOR(i, a, n) for (int i = (a); i < (n); ++i)
#define FOE(i, a) for (auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v, x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT_COUNT(bit) (__builtin_popcount(bit))

typedef long long LL;
template <typename T> std::vector<T> make_v(size_t a) {
  return std::vector<T>(a);
}
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return std::vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
} // C++14
template <typename T, typename V>
typename std::enable_if<std::is_class<T>::value == 0>::type fill_v(T &t,
                                                                   const V &v) {
  t = v;
}
template <typename T, typename V>
typename std::enable_if<std::is_class<T>::value != 0>::type fill_v(T &t,
                                                                   const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}
template <class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
void print() { std::cout << std::endl; }
template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  std::cout << head;
  if (sizeof...(tail) != 0) {
    std::cout << " ";
  }
  print(std::forward<Tail>(tail)...);
}
template <class T> void print(std::vector<T> &v) {
  for (auto &a : v) {
    std::cout << a;
    if (&a != &v.back()) {
      std::cout << " ";
    }
  }
  std::cout << std::endl;
}
template <class T> void print(std::vector<std::vector<T>> &vv) {
  for (auto &v : vv) {
    print(v);
  }
}
void debug() { std::cerr << std::endl; }
template <class Head, class... Tail> void debug(Head &&head, Tail &&...tail) {
  std::cerr << head;
  if (sizeof...(tail) != 0) {
    std::cerr << " ";
  }
  print(std::forward<Tail>(tail)...);
}
template <class T> void debug(std::vector<T> &v) {
  for (auto &a : v) {
    std::cerr << a;
    if (&a != &v.back()) {
      std::cerr << " ";
    }
  }
  std::cerr << std::endl;
}
template <class T> void debug(std::vector<std::vector<T>> &vv) {
  for (auto &v : vv) {
    print(v);
  }
}
inline bool inside(long long y, long long x, long long H, long long W) {
  return 0 <= y and y < H and 0 <= x and x < W;
}
template <class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
template <class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) {
  return abs(x1 - x2) + abs(y1 - y2);
}
template <typename T> T &chmin(T &a, const T &b) { return a = std::min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = std::max(a, b); }
bool is_bit_on(const unsigned long long bit, const unsigned int i) {
  return (bit >> i) & 1u;
}
unsigned long long bit_set(const unsigned long long bit, const unsigned int i,
                           const unsigned int b) {
  assert(b == 0 or b == 1);
  if (b == 0) {
    return bit & ~(1ull << i);
  } else {
    return bit | (1ull << i);
  }
}

// 初項s交差d長さnの数列の和
long long sum_of_arithmetic_progression(long long s, long long d, long long n) {
  return n * (2 * s + (n - 1) * d) / 2;
}

// xが2の階乗かどうか判定
bool is_power_of_two(long long x) { return !(x & (x - 1)); }

long long gcd(long long a, long long b) {
  if (b == 0) {
    return a;
  }
  return gcd(b, a % b);
}

long long gcd(std::vector<long long> &v) {
  long long ans = v[0];
  for (int i = 1; i < (int)v.size(); ++i) {
    ans = gcd(ans, v[i]);
  }
  return ans;
}

long long lcm(long long a, long long b) {
  long long g = gcd(a, b);
  return a / g * b;
}

const int INF = 1u << 30u; // 1,073,741,824
const long long LINF = 1ull << 60u;
const double EPS = 1e-9;
const long double PI = acos(-1.0);
const std::vector<int> dy2 = {0, 1}, dx2 = {1, 0};
const std::vector<int> dy4 = {0, 1, 0, -1}, dx4 = {1, 0, -1, 0};
const std::vector<int> dy8 = {0, -1, 0, 1, 1, -1, -1, 1},
                       dx8 = {1, 0, -1, 0, 1, 1, -1, -1};

std::vector<int> A;
// 1回の伸縮の計算量がaのときO(a(N + Q)sqrt(N))
class Mo {
  struct Query {
    int id;
    int left;
    int right;
  };

public:
  int num_query;                   // クエリの数
  std::vector<Query> query;        // クエリ
  const int num_bucket;            // バケットの数
  int now_left = 0, now_right = 0; // 現在見ている区間[now_left, now_right)

  // 問題特有に必要な変数
  std::vector<int> counter;

  Mo(const int n, const int num_query)
      : num_query(num_query), num_bucket((int)sqrt(n)) {
    this->counter.resize(n);
    this->query.resize(num_query);
  }

  // [l, r)
  void add_query(int id, int l, int r) {
    this->query[id].id = id;
    this->query[id].left = l;
    this->query[id].right = r;
  }

  // クエリをソートする
  void build() {
    std::sort(this->query.begin(), this->query.end(),
              [&](const Query &lhs, const Query &rhs) -> bool {
                const unsigned int left_bucket = lhs.left / this->num_bucket;
                const unsigned int right_bucket = rhs.left / this->num_bucket;
                // クエリの左が所属するバケットが違うなら，クエリの左で比較(=所属するバケットで比較)
                if (left_bucket != right_bucket) {
                  return left_bucket < right_bucket;
                }

                // 定数倍高速化
                // 奇数のバケットだけ右のソート順を逆にする
                if (left_bucket & 1u) {
                  return lhs.right < rhs.right;
                }

                return lhs.right > rhs.right;
              });
  }

  std::vector<int> solve() {
    std::vector<int> ans(this->num_query);

    int query_ans = 0;
    for (int i = 0; i < this->num_query; ++i) {
      const int id = this->query[i].id;
      const int left = this->query[i].left;
      const int right = this->query[i].right;

      // [now_left, now_right)をqueryの[left, right)になるように調整
      while (left < this->now_left) {
        this->add(--this->now_left, query_ans);
      }
      while (this->now_left < left) {
        this->del(this->now_left++, query_ans);
      }

      while (this->now_right < right) {
        this->add(this->now_right++, query_ans);
      }
      while (this->now_right > right) {
        this->del(--this->now_right, query_ans);
      }

      ans[id] = query_ans;
    }

    return ans;
  }

private:
  // A[idx]が追加されたときの操作
  inline void add(const int idx, int &query_ans) {
    ++counter[A[idx]];
    query_ans += (counter[A[idx]] == 1);
  }

  // A[idx]が削除されたときの操作
  inline void del(const int idx, int &query_ans) {
    --counter[A[idx]];
    query_ans -= (counter[A[idx]] == 0);
  }
};

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);

  int N, Q;
  cin >> N >> Q;

  A.resize(N);
  FOR(i, 0, N) { cin >> A[i]; }

  Mo mo(N, Q);
  FOR(i, 0, Q) {
    int L, R;
    cin >> L >> R;
    mo.add_query(i, L - 1, R);
  }

  mo.build();

  auto ans = mo.solve();
  FOE(&a, ans) { print(a); }

  return 0;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <array>
#include <assert.h>
#include <bitset>
#include <climits>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#define LEN(x) (long long)(x.size())
#define FOR(i, a, n) for (int i = (a); i < (n); ++i)
#define FOE(i, a) for (auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v, x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT_COUNT(bit) (__builtin_popcount(bit))

typedef long long LL;
template <typename T> std::vector<T> make_v(size_t a) {
  return std::vector<T>(a);
}
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return std::vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
} // C++14
template <typename T, typename V>
typename std::enable_if<std::is_class<T>::value == 0>::type fill_v(T &t,
                                                                   const V &v) {
  t = v;
}
template <typename T, typename V>
typename std::enable_if<std::is_class<T>::value != 0>::type fill_v(T &t,
                                                                   const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}
template <class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
void print() { std::cout << std::endl; }
template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  std::cout << head;
  if (sizeof...(tail) != 0) {
    std::cout << " ";
  }
  print(std::forward<Tail>(tail)...);
}
template <class T> void print(std::vector<T> &v) {
  for (auto &a : v) {
    std::cout << a;
    if (&a != &v.back()) {
      std::cout << " ";
    }
  }
  std::cout << std::endl;
}
template <class T> void print(std::vector<std::vector<T>> &vv) {
  for (auto &v : vv) {
    print(v);
  }
}
void debug() { std::cerr << std::endl; }
template <class Head, class... Tail> void debug(Head &&head, Tail &&...tail) {
  std::cerr << head;
  if (sizeof...(tail) != 0) {
    std::cerr << " ";
  }
  print(std::forward<Tail>(tail)...);
}
template <class T> void debug(std::vector<T> &v) {
  for (auto &a : v) {
    std::cerr << a;
    if (&a != &v.back()) {
      std::cerr << " ";
    }
  }
  std::cerr << std::endl;
}
template <class T> void debug(std::vector<std::vector<T>> &vv) {
  for (auto &v : vv) {
    print(v);
  }
}
inline bool inside(long long y, long long x, long long H, long long W) {
  return 0 <= y and y < H and 0 <= x and x < W;
}
template <class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
template <class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) {
  return abs(x1 - x2) + abs(y1 - y2);
}
template <typename T> T &chmin(T &a, const T &b) { return a = std::min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = std::max(a, b); }
bool is_bit_on(const unsigned long long bit, const unsigned int i) {
  return (bit >> i) & 1u;
}
unsigned long long bit_set(const unsigned long long bit, const unsigned int i,
                           const unsigned int b) {
  assert(b == 0 or b == 1);
  if (b == 0) {
    return bit & ~(1ull << i);
  } else {
    return bit | (1ull << i);
  }
}

// 初項s交差d長さnの数列の和
long long sum_of_arithmetic_progression(long long s, long long d, long long n) {
  return n * (2 * s + (n - 1) * d) / 2;
}

// xが2の階乗かどうか判定
bool is_power_of_two(long long x) { return !(x & (x - 1)); }

long long gcd(long long a, long long b) {
  if (b == 0) {
    return a;
  }
  return gcd(b, a % b);
}

long long gcd(std::vector<long long> &v) {
  long long ans = v[0];
  for (int i = 1; i < (int)v.size(); ++i) {
    ans = gcd(ans, v[i]);
  }
  return ans;
}

long long lcm(long long a, long long b) {
  long long g = gcd(a, b);
  return a / g * b;
}

const int INF = 1u << 30u; // 1,073,741,824
const long long LINF = 1ull << 60u;
const double EPS = 1e-9;
const long double PI = acos(-1.0);
const std::vector<int> dy2 = {0, 1}, dx2 = {1, 0};
const std::vector<int> dy4 = {0, 1, 0, -1}, dx4 = {1, 0, -1, 0};
const std::vector<int> dy8 = {0, -1, 0, 1, 1, -1, -1, 1},
                       dx8 = {1, 0, -1, 0, 1, 1, -1, -1};

std::vector<int> A;
// 1回の伸縮の計算量がaのときO(a(N + Q)sqrt(N))
class Mo {
  struct Query {
    int id;
    int left;
    int right;
  };

public:
  int num_query;                   // クエリの数
  std::vector<Query> query;        // クエリ
  const int num_bucket;            // バケットの数
  int now_left = 0, now_right = 0; // 現在見ている区間[now_left, now_right)

  // 問題特有に必要な変数
  std::vector<int> counter;

  Mo(const int n, const int num_query)
      : num_query(num_query), num_bucket((int)sqrt(n)) {
    this->counter.resize(n);
    this->query.resize(num_query);
  }

  // [l, r)
  void add_query(int id, int l, int r) {
    this->query[id].id = id;
    this->query[id].left = l;
    this->query[id].right = r;
  }

  // クエリをソートする
  void build() {
    std::sort(this->query.begin(), this->query.end(),
              [&](const Query &lhs, const Query &rhs) -> bool {
                // クエリの左が所属するバケットが同じならクエリの右で比較
                if ((lhs.left / this->num_bucket) ==
                    (rhs.left / this->num_bucket)) {
                  return lhs.right < rhs.right;
                }
                // クエリの左が所属するバケットが違うなら，クエリの右で比較(=所属するバケットで比較)
                return lhs.left < rhs.left;
              });
  }

  std::vector<int> solve() {
    std::vector<int> ans(this->num_query);

    int query_ans = 0;
    for (int i = 0; i < this->num_query; ++i) {
      const int id = this->query[i].id;
      const int left = this->query[i].left;
      const int right = this->query[i].right;

      // [now_left, now_right)をqueryの[left, right)になるように調整
      while (left < this->now_left) {
        this->add(--this->now_left, query_ans);
      }
      while (this->now_left < left) {
        this->del(this->now_left++, query_ans);
      }

      while (this->now_right < right) {
        this->add(this->now_right++, query_ans);
      }
      while (this->now_right > right) {
        this->del(--this->now_right, query_ans);
      }

      ans[id] = query_ans;
    }

    return ans;
  }

private:
  // A[idx]が追加されたときの操作
  inline void add(const int idx, int &query_ans) {
    ++counter[A[idx]];
    query_ans += (counter[A[idx]] == 1);
  }

  // A[idx]が削除されたときの操作
  inline void del(const int idx, int &query_ans) {
    --counter[A[idx]];
    query_ans -= (counter[A[idx]] == 0);
  }
};

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);

  LL N, Q;
  cin >> N >> Q;

  A = make_v<int>(N);
  FOR(i, 0, N) { cin >> A[i]; }

  Mo mo(N, Q);
  FOR(i, 0, Q) {
    LL L, R;
    cin >> L >> R;
    mo.add_query(i, L - 1, R);
  }

  mo.build();

  auto ans = mo.solve();
  FOE(&a, ans) { print(a); }

  return 0;
}