Problem p02599 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
#pragma gcc optimize("O3")
#pragma gcc optimize("unroll-loops")
#ifdef EVAH
#define _WIN32_WINNT 0x0500
#include <windows.h>
#endif
#define openFile(n)                                                            \
  ShellExecute(nullptr, "open", n, nullptr, nullptr, SW_SHOWNORMAL);
#define closeP(n) system((string("taskkill /im ") + n + " /f").c_str());
#define closeConsole PostMessage(GetConsoleWindow(), WM_CLOSE, 0, 0);
#define opf "output.txt"
#define ipf "input.txt"
#define mem(n, x) memset(n, x, sizeof(n));
#define sf scanf
#define pf printf
#define ff first
#define ss second
#define pb push_back
#define PII pair<int, int>
#define For(x, n) for (int i = x; i < n; i++)
#define stv v + 2 * (mid - tl + 1)
#define LL long long int
#define PI acos(-1.0)
#define N 500001

const int blockSize = 400;

struct query {
  int l, r, idx;
  bool operator<(query other) const {
    if (l / blockSize != other.l / blockSize)
      return l < other.l;
    return (l / blockSize & 1) ? (r < other.r) : (r > other.r);
  }
};

vector<int> clr(N), appeared(N);
int tempAns = 0;

void rmv(int idx) {
  appeared[clr[idx]]--;
  if (!appeared[clr[idx]])
    tempAns--;
}
void add(int idx) {
  if (!appeared[clr[idx]])
    tempAns++;
  appeared[clr[idx]]++;
}
int get_ans() { return tempAns; }

vector<int> mosAlgo(vector<query> queries) {
  vector<int> ans(queries.size());
  sort(queries.begin(), queries.end());
  int curL = 0;
  int curR = -1;
  for (query q : queries) {
    while (curL > q.l) {
      curL--;
      add(curL);
    }
    while (curR < q.r) {
      curR++;
      add(curR);
    }
    while (curL < q.l) {
      rmv(curL);
      curL++;
    }
    while (curR > q.r) {
      rmv(curR);
      curR--;
    }
    ans[q.idx] = get_ans();
  }
  return ans;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
#ifdef EVAH
  // freopen(ipf,"r",stdin);
  // openFile(ipf);
  // closeConsole;
  // freopen(opf,"w",stdout);
#endif

  int n, q, l, r;
  cin >> n >> q;
  // blockSize = sqrt(n);
  vector<query> queries(q);
  For(0, n) { cin >> clr[i]; }
  For(0, q) {
    queries[i].idx = i;
    cin >> queries[i].l >> queries[i].r;
    queries[i].l--;
    queries[i].r--;
  }
  vector<int> ans = mosAlgo(queries);
  For(0, ans.size()) { cout << ans[i] << "\n"; }

#ifdef EVAH
  // openFile(opf);
  // Sleep(3000);
  // closeP("notepad.exe");
  // closeConsole;
#endif
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#pragma gcc optimize("O3")
#pragma gcc optimize("unroll-loops")
#ifdef EVAH
#define _WIN32_WINNT 0x0500
#include <windows.h>
#endif
#define openFile(n)                                                            \
  ShellExecute(nullptr, "open", n, nullptr, nullptr, SW_SHOWNORMAL);
#define closeP(n) system((string("taskkill /im ") + n + " /f").c_str());
#define closeConsole PostMessage(GetConsoleWindow(), WM_CLOSE, 0, 0);
#define opf "output.txt"
#define ipf "input.txt"
#define mem(n, x) memset(n, x, sizeof(n));
#define sf scanf
#define pf printf
#define ff first
#define ss second
#define pb push_back
#define PII pair<int, int>
#define For(x, n) for (int i = x; i < n; i++)
#define stv v + 2 * (mid - tl + 1)
#define LL long long int
#define PI acos(-1.0)
#define N 500001

const int blockSize = 800;

struct query {
  int l, r, idx;
  bool operator<(query other) const {
    if (l / blockSize != other.l / blockSize)
      return l < other.l;
    return (l / blockSize & 1) ? (r < other.r) : (r > other.r);
  }
};

vector<int> clr(N), appeared(N);
int tempAns = 0;

void rmv(int idx) {
  appeared[clr[idx]]--;
  if (!appeared[clr[idx]])
    tempAns--;
}
void add(int idx) {
  if (!appeared[clr[idx]])
    tempAns++;
  appeared[clr[idx]]++;
}
int get_ans() { return tempAns; }

vector<int> mosAlgo(vector<query> queries) {
  vector<int> ans(queries.size());
  sort(queries.begin(), queries.end());
  int curL = 0;
  int curR = -1;
  for (query q : queries) {
    while (curL > q.l) {
      curL--;
      add(curL);
    }
    while (curR < q.r) {
      curR++;
      add(curR);
    }
    while (curL < q.l) {
      rmv(curL);
      curL++;
    }
    while (curR > q.r) {
      rmv(curR);
      curR--;
    }
    ans[q.idx] = get_ans();
  }
  return ans;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
#ifdef EVAH
  // freopen(ipf,"r",stdin);
  // openFile(ipf);
  // closeConsole;
  // freopen(opf,"w",stdout);
#endif

  int n, q, l, r;
  cin >> n >> q;
  // blockSize = sqrt(n);
  vector<query> queries(q);
  For(0, n) { cin >> clr[i]; }
  For(0, q) {
    queries[i].idx = i;
    cin >> queries[i].l >> queries[i].r;
    queries[i].l--;
    queries[i].r--;
  }
  vector<int> ans = mosAlgo(queries);
  For(0, ans.size()) { cout << ans[i] << "\n"; }

#ifdef EVAH
  // openFile(opf);
  // Sleep(3000);
  // closeP("notepad.exe");
  // closeConsole;
#endif
}