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

#include <bits/stdc++.h>

using namespace std;

#define DEBUG(x) cerr << #x << ": " << x << endl;
#define DEBUG_VEC(v)                                                           \\
  cerr << #v << ":";                                                           \\
  for (int i = 0; i < v.size(); i++)                                           \\
    cerr << " " << v[i];                                                       \\
  cerr << endl;
#define DEBUG_MAT(v)                                                           \\
  cerr << #v << endl;                                                          \\
  for (int i = 0; i < v.size(); i++) {                                         \\
    for (int j = 0; j < v[i].size(); j++) {                                    \\
      cerr << v[i][j] << " ";                                                  \\
    }                                                                          \\
    cerr << endl;                                                              \\
  }
typedef long long ll;
// #define int ll

#define vi vector<int>
#define vl vector<ll>
#define vii vector<vector<int>>
#define vll vector<vector<ll>>
#define vs vector<string>
#define pii pair<int, int>
#define pis pair<int, string>
#define psi pair<string, int>
#define pll pair<ll, ll>
template <class S, class T>
pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
template <class S, class T> ostream &operator<<(ostream &os, pair<S, T> p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
#define X first
#define Y second
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rrep1(i, n) for (int i = (int)(n); i > 0; i--)
#define REP(i, a, b) for (int i = a; i < b; i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(), c.end()
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout << setprecision(25) << fixed << p << endl;
// int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
// int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
// vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio()                                                                  \\
  cin.tie(0);                                                                  \\
  ios::sync_with_stdio(false);
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
// #define endl '\\n'

class Bit {
public:
  int n;
  vl bit; // 0-index

  Bit(int _n) {
    n = _n;
    bit.resize(n);
  }

  // [0, i)�̘a
  ll sum(int i) {
    ll s = 0;
    while (i > 0) {
      s += bit[i - 1];
      i -= i & -i;
    }
    return s;
  }

  // i��0-index
  void add(int i, ll x) {
    i++;
    while (i <= n) {
      bit[i - 1] += x;
      i += i & -i;
    }
  }

  // bit�ɓ����Ă钆��x�Ԗڂɏ������������߂�
  // 1�ԏ���������x = 1;
  // bit��3�����遨add(3, 1), 3���o����add(3, -1)
  // return == n�̏ꍇx�������Ă��Ȃ�
  ll min_xth(int x) {
    int left = -1, right = n;
    while (left + 1 < right) {
      int mid = (left + right) / 2;
      int temp = sum(mid + 1);
      if (temp < x) {
        left = mid;
      } else {
        right = mid;
      }
    }
    return right;
  }

  // p�����Ԓʂ�ɂ��邽�߂̌�����
  ll bubble(vi p) {
    int n = p.size();
    ll ans = 0;
    for (int j = 0; j < n; j++) {
      ans += (j - sum(p[j] + 1));
      add(p[j], 1);
    }
    return ans;
  }
};

signed main() {
  fio();
  int n, q;
  cin >> n >> q;
  vi c(n);
  rep(i, n) {
    cin >> c[i];
    c[i]--;
  }

  vector<pii> lr(q);
  rep(i, q) {
    cin >> lr[i].first >> lr[i].second;
    lr[i].first--;
  }

  vi order(q);
  vi ans(q);
  rep(i, q) order[i] = i;
  sort(all(order), [&](int i, int j) {
    pii lr1 = lr[i], lr2 = lr[j];
    if (lr1.second != lr2.second)
      return lr1.second < lr2.second;
    else
      return lr1 < lr2;
  });

  vi last(n, -1);
  Bit bit(n);
  int r = 0;
  for (int i : order) {
    while (r < lr[i].second) {
      int pre_last = last[c[r]];
      if (pre_last != -1) {
        bit.add(pre_last, -1);
      }
      last[c[r]] = r;
      bit.add(last[c[r]], 1);
      r++;
    }

    ans[i] = bit.sum(lr[i].second) - bit.sum(lr[i].first);
  }

  rep(i, ans.size()) { cout << ans[i] << endl; }
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

#define DEBUG(x) cerr << #x << ": " << x << endl;
#define DEBUG_VEC(v)                                                           \\
  cerr << #v << ":";                                                           \\
  for (int i = 0; i < v.size(); i++)                                           \\
    cerr << " " << v[i];                                                       \\
  cerr << endl;
#define DEBUG_MAT(v)                                                           \\
  cerr << #v << endl;                                                          \\
  for (int i = 0; i < v.size(); i++) {                                         \\
    for (int j = 0; j < v[i].size(); j++) {                                    \\
      cerr << v[i][j] << " ";                                                  \\
    }                                                                          \\
    cerr << endl;                                                              \\
  }
typedef long long ll;
// #define int ll

#define vi vector<int>
#define vl vector<ll>
#define vii vector<vector<int>>
#define vll vector<vector<ll>>
#define vs vector<string>
#define pii pair<int, int>
#define pis pair<int, string>
#define psi pair<string, int>
#define pll pair<ll, ll>
template <class S, class T>
pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
template <class S, class T> ostream &operator<<(ostream &os, pair<S, T> p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
#define X first
#define Y second
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rrep1(i, n) for (int i = (int)(n); i > 0; i--)
#define REP(i, a, b) for (int i = a; i < b; i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(), c.end()
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout << setprecision(25) << fixed << p << endl;
// int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
// int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
// vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio()                                                                  \\
  cin.tie(0);                                                                  \\
  ios::sync_with_stdio(false);
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
// #define endl '\\n'

const int N = 512345;
vi num(N);
vi c(N);
int ans = 0;
vi res(N);

struct Mo {
  using ADD = function<void(int)>;
  using DEL = function<void(int)>;
  using REM = function<void(int)>;

  int width;
  vector<int> left, right, order;
  vector<bool> v;

  Mo(int N, int Q) : width((int)sqrt(N)), order(Q), v(N) {
    iota(begin(order), end(order), 0);
  }

  void add(int l, int r) { /* [l, r) */
    left.emplace_back(l);
    right.emplace_back(r);
  }

  void run(const ADD &add, const DEL &del, const REM &rem) {
    assert(left.size() == order.size());
    sort(begin(order), end(order), [&](int a, int b) {
      int ablock = left[a] / width, bblock = left[b] / width;
      if (ablock != bblock)
        return ablock < bblock;
      if (ablock & 1)
        return right[a] < right[b];
      return right[a] > right[b];
    });
    int nl = 0, nr = 0;
    auto push = [&](int idx) {
      v[idx].flip();
      if (v[idx])
        add(idx);
      else
        del(idx);
    };
    for (auto idx : order) {
      while (nl > left[idx])
        push(--nl);
      while (nr < right[idx])
        push(nr++);
      while (nl < left[idx])
        push(nl++);
      while (nr > right[idx])
        push(--nr);
      rem(idx);
    }
  }
};

signed main() {
  fio();
  int n, q;
  scanf("%d %d", &n, &q);
  // cin >> n >> q;
  rep(i, n) {
    // cin >> c[i];
    scanf("%d", &c[i]);
    c[i]--;
  }

  auto add = [&](int i) {
    num[c[i]]++;
    if (num[c[i]] == 1)
      ans++;
  };

  auto del = [&](int i) {
    num[c[i]]--;
    if (num[c[i]] == 0)
      ans--;
  };

  auto rem = [&](int i) { res[i] = ans; };

  Mo mo(n, q);
  rep(i, q) {
    int l, r;
    scanf("%d %d", &l, &r);
    // cin >> l >> r;
    mo.add(l - 1, r);
  }
  mo.run(add, del, rem);

  rep(i, q) {
    printf("%d\\n", res[i]);
    // cout << res[i] << '\\n';
  }
}