Problem p02537 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
template <class T1, class T2> ostream &operator<<(ostream &s, pair<T1, T2> P) {
  return s << '<' << P.first << ", " << P.second << '>';
}
template <class T> ostream &operator<<(ostream &s, vector<T> P) {
  for (int i = 0; i < P.size(); ++i) {
    if (i > 0) {
      s << " ";
    }
    s << P[i];
  }
  return s;
}
template <class T> ostream &operator<<(ostream &s, vector<vector<T>> P) {
  for (int i = 0; i < P.size(); ++i) {
    s << endl << P[i];
  }
  return s << endl;
}
template <class T> ostream &operator<<(ostream &s, set<T> P) {
  for (auto it : P) {
    s << "<" << it << "> ";
  }
  return s << endl;
}
template <class T1, class T2> ostream &operator<<(ostream &s, map<T1, T2> P) {
  for (auto it : P) {
    s << "<" << it.first << "->" << it.second << "> ";
  }
  return s << endl;
}

template <class Monoid> struct SegTree {
  using Func = function<Monoid(Monoid, Monoid)>;
  const Func F;
  const Monoid UNITY;
  int SIZE_R;
  vector<Monoid> dat;

  SegTree(int n, const Func f, const Monoid &unity) : F(f), UNITY(unity) {
    init(n);
  }
  void init(int n) {
    SIZE_R = 1;
    while (SIZE_R < n)
      SIZE_R *= 2;
    dat.assign(SIZE_R * 2, UNITY);
  }

  /* set, a is 0-indexed */
  void set(int a, const Monoid &v) { dat[a + SIZE_R] = v; }
  void build() {
    for (int k = SIZE_R - 1; k > 0; --k)
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
  }

  /* update a, a is 0-indexed */
  void update(int a, const Monoid &v) {
    int k = a + SIZE_R;
    dat[k] = v;
    while (k >>= 1)
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
  }

  /* get [a, b), a and b are 0-indexed */
  Monoid get(int a, int b) {
    Monoid vleft = UNITY, vright = UNITY;
    for (int left = a + SIZE_R, right = b + SIZE_R; left < right;
         left >>= 1, right >>= 1) {
      if (left & 1)
        vleft = F(vleft, dat[left++]);
      if (right & 1)
        vright = F(dat[--right], vright);
    }
    return F(vleft, vright);
  }
  inline Monoid operator[](int a) { return dat[a + SIZE_R]; }

  /* debug */
  void print() {
    for (int i = 0; i < SIZE_R; ++i) {
      cout << (*this)[i];
      if (i != SIZE_R - 1)
        cout << ",";
    }
    cout << endl;
  }
};

int solve(int N, int K) {
  const int MAX = 510000;
  auto func = [&](int a, int b) { return max(a, b); };
  SegTree<int> seg(MAX, func, 0);
  for (int i = 0; i < N; ++i) {
    int a;
    cin >> a;
    int left = max(0, a - K);
    int right = min(MAX, a + K + 1);
    int val = seg.get(left, right);
    seg.update(a, val + 1);

    // seg.print(); COUT(val);
  }
  return seg.get(0, MAX);
}

int main() {
  int N, K;
  while (cin >> N >> K)
    cout << solve(N, K) << endl;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
template <class T1, class T2> ostream &operator<<(ostream &s, pair<T1, T2> P) {
  return s << '<' << P.first << ", " << P.second << '>';
}
template <class T> ostream &operator<<(ostream &s, vector<T> P) {
  for (int i = 0; i < P.size(); ++i) {
    if (i > 0) {
      s << " ";
    }
    s << P[i];
  }
  return s;
}
template <class T> ostream &operator<<(ostream &s, vector<vector<T>> P) {
  for (int i = 0; i < P.size(); ++i) {
    s << endl << P[i];
  }
  return s << endl;
}
template <class T> ostream &operator<<(ostream &s, set<T> P) {
  for (auto it : P) {
    s << "<" << it << "> ";
  }
  return s << endl;
}
template <class T1, class T2> ostream &operator<<(ostream &s, map<T1, T2> P) {
  for (auto it : P) {
    s << "<" << it.first << "->" << it.second << "> ";
  }
  return s << endl;
}

template <class Monoid> struct SegTree {
  using Func = function<Monoid(Monoid, Monoid)>;
  const Func F;
  const Monoid UNITY;
  int SIZE_R;
  vector<Monoid> dat;

  SegTree(int n, const Func f, const Monoid &unity) : F(f), UNITY(unity) {
    init(n);
  }
  void init(int n) {
    SIZE_R = 1;
    while (SIZE_R < n)
      SIZE_R *= 2;
    dat.assign(SIZE_R * 2, UNITY);
  }

  /* set, a is 0-indexed */
  void set(int a, const Monoid &v) { dat[a + SIZE_R] = v; }
  void build() {
    for (int k = SIZE_R - 1; k > 0; --k)
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
  }

  /* update a, a is 0-indexed */
  void update(int a, const Monoid &v) {
    int k = a + SIZE_R;
    dat[k] = v;
    while (k >>= 1)
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
  }

  /* get [a, b), a and b are 0-indexed */
  Monoid get(int a, int b) {
    Monoid vleft = UNITY, vright = UNITY;
    for (int left = a + SIZE_R, right = b + SIZE_R; left < right;
         left >>= 1, right >>= 1) {
      if (left & 1)
        vleft = F(vleft, dat[left++]);
      if (right & 1)
        vright = F(dat[--right], vright);
    }
    return F(vleft, vright);
  }
  inline Monoid operator[](int a) { return dat[a + SIZE_R]; }

  /* debug */
  void print() {
    for (int i = 0; i < SIZE_R; ++i) {
      cout << (*this)[i];
      if (i != SIZE_R - 1)
        cout << ",";
    }
    cout << endl;
  }
};

int solve(int N, int K) {
  const int MAX = 10; // 510000;
  auto func = [&](int a, int b) { return max(a, b); };
  SegTree<int> seg(N, func, 0);
  for (int i = 0; i < N; ++i) {
    int a;
    cin >> a;
    int left = max(0, a - K);
    int right = min(N, a + K + 1);
    int val = seg.get(left, right);
    seg.update(a, val + 1);

    // seg.print(); COUT(val);
  }
  return seg.get(0, MAX);
}

int main() {
  int N, K;
  while (cin >> N >> K)
    cout << solve(N, K) << endl;
}