Problem p02537 (C++)

Buggy submission (status: Runtime Error):
/*
    Created by Rahul Goel.
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
/*******************************************************************************/
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
/*******************************************************************************/
using ll = long long;
using ld = long double;
const ll MOD = 1000000007;
// const ll MOD = 998244353;
const int INF = 1e9;
const ll LINF = 1e18;
/*******************************************************************************/
ll mod_sum() { return 0LL; }
template <typename T, typename... Args> T mod_sum(T a, Args... args) {
  return ((a + mod_sum(args...)) % MOD + MOD) % MOD;
}
/*******************************************************************************/
ll mod_prod() { return 1LL; }
template <typename T, typename... Args> T mod_prod(T a, Args... args) {
  return (a * mod_prod(args...)) % MOD;
}
/*******************************************************************************/
#ifdef ONLINE_JUDGE
#define endl '\n'
#endif
#define fastio                                                                 \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
#define all(c) (c).begin(), (c).end()
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define uniq(c) (c).resize(distance((c).begin(), unique(all(c))))
#define min_pq(t) priority_queue<t, vector<t>, greater<t>>
#define max_pq(t) priority_queue<t>
#define pb push_back
#define ff first
#define ss second
/*******************************************************************************/
using pii = pair<int, int>;
using vi = vector<int>;
using vb = vector<bool>;
using vvi = vector<vector<int>>;
using vvb = vector<vector<bool>>;
using vpii = vector<pii>;
using vvpii = vector<vector<pii>>;
/*******************************************************************************/
//.-.. . -. -.- .- .. ... .-.. --- ...- .
/*
    Code begins after this.
*/

struct SegmentTree {
  vi t;

  SegmentTree(int n) { t.resize(n << 2); }

  void pull(int v) { t[v] = max(t[v << 1], t[v << 1 | 1]); }

  void upd(int v, int tl, int tr, int pos, int val) {
    if (tl == tr) {
      t[v] = val;
      return;
    }
    int tm = (tl + tr) >> 1;
    if (pos <= tm) {
      upd(v << 1, tl, tm, pos, val);
    } else {
      upd(v << 1 | 1, tm + 1, tr, pos, val);
    }
    pull(v);
  }

  int query(int v, int tl, int tr, int ql, int qr) {
    if (ql <= tl && tr <= qr) {
      return t[v];
    }
    int tm = (tl + tr) >> 1;
    int ret = -INF;
    if (ql <= tm) {
      ret = max(ret, query(v << 1, tl, tm, ql, qr));
    }
    if (tm + 1 <= qr) {
      ret = max(ret, query(v << 1 | 1, tm + 1, tr, ql, qr));
    }
    pull(v);
    return ret;
  }
};

int solve() {
  int n, k;
  cin >> n >> k;
  SegmentTree st(300005);

  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    int y = st.query(1, 0, n - 1, max(0, x - k), min(300000, x + k));
    st.upd(1, 0, n - 1, x, y + 1);
  }

  int ans = st.query(1, 0, 300005 - 1, 0, 300000);
  cout << ans << endl;

  return 0;
}

signed main() {
  fastio;

  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}


Fixed submission:
/*
    Created by Rahul Goel.
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
/*******************************************************************************/
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
/*******************************************************************************/
using ll = long long;
using ld = long double;
const ll MOD = 1000000007;
// const ll MOD = 998244353;
const int INF = 1e9;
const ll LINF = 1e18;
/*******************************************************************************/
ll mod_sum() { return 0LL; }
template <typename T, typename... Args> T mod_sum(T a, Args... args) {
  return ((a + mod_sum(args...)) % MOD + MOD) % MOD;
}
/*******************************************************************************/
ll mod_prod() { return 1LL; }
template <typename T, typename... Args> T mod_prod(T a, Args... args) {
  return (a * mod_prod(args...)) % MOD;
}
/*******************************************************************************/
#ifdef ONLINE_JUDGE
#define endl '\n'
#endif
#define fastio                                                                 \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
#define all(c) (c).begin(), (c).end()
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define uniq(c) (c).resize(distance((c).begin(), unique(all(c))))
#define min_pq(t) priority_queue<t, vector<t>, greater<t>>
#define max_pq(t) priority_queue<t>
#define pb push_back
#define ff first
#define ss second
/*******************************************************************************/
using pii = pair<int, int>;
using vi = vector<int>;
using vb = vector<bool>;
using vvi = vector<vector<int>>;
using vvb = vector<vector<bool>>;
using vpii = vector<pii>;
using vvpii = vector<vector<pii>>;
/*******************************************************************************/
//.-.. . -. -.- .- .. ... .-.. --- ...- .
/*
    Code begins after this.
*/

struct SegmentTree {
  vi t;

  SegmentTree(int n) { t.resize(n << 2); }

  void pull(int v) { t[v] = max(t[v << 1], t[v << 1 | 1]); }

  void upd(int v, int tl, int tr, int pos, int val) {
    if (tl == tr) {
      t[v] = val;
      return;
    }
    int tm = (tl + tr) >> 1;
    if (pos <= tm) {
      upd(v << 1, tl, tm, pos, val);
    } else {
      upd(v << 1 | 1, tm + 1, tr, pos, val);
    }
    pull(v);
  }

  int query(int v, int tl, int tr, int ql, int qr) {
    if (ql <= tl && tr <= qr) {
      return t[v];
    }
    int tm = (tl + tr) >> 1;
    int ret = -INF;
    if (ql <= tm) {
      ret = max(ret, query(v << 1, tl, tm, ql, qr));
    }
    if (tm + 1 <= qr) {
      ret = max(ret, query(v << 1 | 1, tm + 1, tr, ql, qr));
    }
    pull(v);
    return ret;
  }
};

int solve() {
  int n, k;
  cin >> n >> k;
  SegmentTree st(300005);

  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    int y = st.query(1, 0, 300005 - 1, max(0, x - k), min(300000, x + k));
    st.upd(1, 0, 300005 - 1, x, y + 1);
  }

  int ans = st.query(1, 0, 300005 - 1, 0, 300000);
  cout << ans << endl;

  return 0;
}

signed main() {
  fastio;

  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}