Problem p02599 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set                                                            \\
  tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
typedef int ll;
// #define int long long
typedef unsigned long long lu;
typedef vector<ll> v;
typedef vector<vector<ll>> vv;
typedef vector<string> vs;
typedef vector<pair<ll, ll>> vpr;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef long double ld;
#define f(i, n) for (ll i = 0; i < n; i++)
#define ff(i, n) for (ll i = 1; i <= n; i++)
#define pb push_back
#define mp make_pair
#define endl "\\n"
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define amax(x, y)                                                             \\
  if (y > x)                                                                   \\
    x = y;
#define amin(x, y)                                                             \\
  if (y < x)                                                                   \\
    x = y;
#define bg(x) x.begin()
#define sz(x) (ll) x.size()
#define in(x, n)                                                               \\
  for (ll i = 0; i < n; i++)                                                   \\
  cin >> x[i]
#define out(x, n)                                                              \\
  for (ll i = 0; i < n; i++)                                                   \\
  cout << x[i] << " "
#define mxt(a) *(max_element(a.begin(), a.end()))
#define mnt(a) *(min_element(a.begin(),a.end())
#define tc                                                                     \\
  ll t;                                                                        \\
  cin >> t;                                                                    \\
  while (t--)
typedef pair<ll, ll> pi;
#define yes cout << "YES\\n";
#define no cout << "NO\\n";
#define yesno(f)                                                               \\
  if (f)                                                                       \\
  yes else no
const v dx = {1, -1, 0, 0};
const v dy = {0, 0, 1, -1};
const ld PI = 2 * acos(0.0);
ll cel(ll x1, ll y1) {
  if ((x1 % y1) == 0)
    return x1 / y1;
  else
    return x1 / y1 + 1;
}
ll power(ll a, ll b, ll m) {
  if (b == 0)
    return 1;
  ll d = power(a, b / 2, m);
  d = (d * d) % m;
  if (b & 1)
    d = (d * a) % m;
  return d;
}
const ll mod = 1e9 + 7;
int MOD(int a) {
  if (a < 0)
    a += mod;
  if (a >= mod)
    a %= mod;
  return a;
}
// set_name.find_by_order(k) It returns to an iterator to the kth element
// (counting from zero) in the set in O(logn) time set_name.order_of_key(k) It
// returns to the number of items that are strictly smaller than our item k in
// O(logn) time.
/*string operations :
str.substr (x,y) : returns a substring str[x],str[x+1],...str[x+y-1]
str.substr (x) : returns a substring str[x],... end of string
str.find(qtr) : returns the first occurenece of qtr in str */
int Nodes = 0;
const int N = 4e7 + 1;
int seg[N], lp[N], rp[N];
int build(int ss, int se) {
  int pos = Nodes++;
  if (ss == se) {
    seg[pos] = 0;
    lp[pos] = -1;
    rp[pos] = -1;
    return pos;
  }
  int mid = (ss + se) / 2;
  lp[pos] = build(ss, mid);
  rp[pos] = build(mid + 1, se);
  seg[pos] = 0;
  // seg[pos]=seg[lp[pos]]+seg[rp[pos]];
  return pos;
}
int update(int root, int ss, int se, int ind, int val) {
  if (ind < ss || ind > se)
    return root;
  int pos = Nodes++;
  if (ss == se) {
    seg[pos] = val;
    return pos;
  }
  int mid = (ss + se) / 2;
  if (ind <= mid) {
    lp[pos] = update(lp[root], ss, mid, ind, val);
    rp[pos] = rp[root];
    seg[pos] = seg[lp[pos]] + seg[rp[pos]];
    return pos;
  } else {
    rp[pos] = update(rp[root], mid + 1, se, ind, val);
    lp[pos] = lp[root];
    seg[pos] = seg[lp[pos]] + seg[rp[pos]];
    return pos;
  }
}
int query(int pos, int ss, int se, int l, int r) {
  if (l <= ss && r >= se) {
    return seg[pos];
  }
  if (l > se || r < ss)
    return 0;
  int mid = (ss + se) / 2;
  return query(lp[pos], ss, mid, l, r) + query(rp[pos], mid + 1, se, l, r);
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int n, q;
  cin >> n >> q;
  v arr(n);
  in(arr, n);
  v next(n, n);
  map<int, int> mapp;
  for (int i = n - 1; i >= 0; i--) {
    if (mapp.count(arr[i]))
      next[i] = mapp[arr[i]];
    mapp[arr[i]] = i;
  }
  v roots;
  int root = build(0, n - 1);
  // roots.pb(root);
  for (int i = n - 1; i >= 0; i--) {
    root = update(root, 0, n - 1, i, 1);
    if (next[i] != n) {
      root = update(root, 0, n - 1, next[i], 0);
    }
    roots.pb(root);
  }
  reverse(all(roots));
  while (q--) {
    int l, r;
    cin >> l >> r;
    cout << query(roots[l - 1], 0, n - 1, l - 1, r - 1) << endl;
  }
  return 0;
}

Error: -11

Fixed submission:

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set                                                            \\
  tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
#define int long long
typedef unsigned long long lu;
typedef vector<ll> v;
typedef vector<vector<ll>> vv;
typedef vector<string> vs;
typedef vector<pair<ll, ll>> vpr;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef long double ld;
#define f(i, n) for (ll i = 0; i < n; i++)
#define ff(i, n) for (ll i = 1; i <= n; i++)
#define pb push_back
#define mp make_pair
#define endl "\\n"
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define amax(x, y)                                                             \\
  if (y > x)                                                                   \\
    x = y;
#define amin(x, y)                                                             \\
  if (y < x)                                                                   \\
    x = y;
#define bg(x) x.begin()
#define sz(x) (ll) x.size()
#define in(x, n)                                                               \\
  for (ll i = 0; i < n; i++)                                                   \\
  cin >> x[i]
#define out(x, n)                                                              \\
  for (ll i = 0; i < n; i++)                                                   \\
  cout << x[i] << " "
#define mxt(a) *(max_element(a.begin(), a.end()))
#define mnt(a) *(min_element(a.begin(),a.end())
#define tc                                                                     \\
  ll t;                                                                        \\
  cin >> t;                                                                    \\
  while (t--)
typedef pair<ll, ll> pi;
#define yes cout << "YES\\n";
#define no cout << "NO\\n";
#define yesno(f)                                                               \\
  if (f)                                                                       \\
  yes else no
const v dx = {1, -1, 0, 0};
const v dy = {0, 0, 1, -1};
const ld PI = 2 * acos(0.0);
ll cel(ll x1, ll y1) {
  if ((x1 % y1) == 0)
    return x1 / y1;
  else
    return x1 / y1 + 1;
}
ll power(ll a, ll b, ll m) {
  if (b == 0)
    return 1;
  ll d = power(a, b / 2, m);
  d = (d * d) % m;
  if (b & 1)
    d = (d * a) % m;
  return d;
}
const ll mod = 1e9 + 7;
int MOD(int a) {
  if (a < 0)
    a += mod;
  if (a >= mod)
    a %= mod;
  return a;
}
// set_name.find_by_order(k) It returns to an iterator to the kth element
// (counting from zero) in the set in O(logn) time set_name.order_of_key(k) It
// returns to the number of items that are strictly smaller than our item k in
// O(logn) time.
/*string operations :
str.substr (x,y) : returns a substring str[x],str[x+1],...str[x+y-1]
str.substr (x) : returns a substring str[x],... end of string
str.find(qtr) : returns the first occurenece of qtr in str */
int Nodes = 0;
const int N = 2e7;
int seg[N], lp[N], rp[N];
int build(int ss, int se) {
  int pos = Nodes++;
  if (ss == se) {
    seg[pos] = 0;
    lp[pos] = -1;
    rp[pos] = -1;
    return pos;
  }
  int mid = (ss + se) / 2;
  lp[pos] = build(ss, mid);
  rp[pos] = build(mid + 1, se);
  seg[pos] = 0;
  // seg[pos]=seg[lp[pos]]+seg[rp[pos]];
  return pos;
}
int update(int root, int ss, int se, int ind, int val) {
  if (ind < ss || ind > se)
    return root;
  int pos = Nodes++;
  if (ss == se) {
    seg[pos] = val;
    return pos;
  }
  int mid = (ss + se) / 2;
  if (ind <= mid) {
    lp[pos] = update(lp[root], ss, mid, ind, val);
    rp[pos] = rp[root];
    seg[pos] = seg[lp[pos]] + seg[rp[pos]];
    return pos;
  } else {
    rp[pos] = update(rp[root], mid + 1, se, ind, val);
    lp[pos] = lp[root];
    seg[pos] = seg[lp[pos]] + seg[rp[pos]];
    return pos;
  }
}
int query(int pos, int ss, int se, int l, int r) {
  if (l <= ss && r >= se) {
    return seg[pos];
  }
  if (l > se || r < ss)
    return 0;
  int mid = (ss + se) / 2;
  return query(lp[pos], ss, mid, l, r) + query(rp[pos], mid + 1, se, l, r);
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int n, q;
  cin >> n >> q;
  v arr(n);
  in(arr, n);
  v next(n, n);
  map<int, int> mapp;
  for (int i = n - 1; i >= 0; i--) {
    if (mapp.count(arr[i]))
      next[i] = mapp[arr[i]];
    mapp[arr[i]] = i;
  }
  v roots;
  int root = build(0, n - 1);
  // roots.pb(root);
  for (int i = n - 1; i >= 0; i--) {
    root = update(root, 0, n - 1, i, 1);
    if (next[i] != n) {
      root = update(root, 0, n - 1, next[i], 0);
    }
    roots.pb(root);
  }
  reverse(all(roots));
  while (q--) {
    int l, r;
    cin >> l >> r;
    cout << query(roots[l - 1], 0, n - 1, l - 1, r - 1) << endl;
  }
  return 0;
}