Problem p02598 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;
#define ALL(x) (x).begin(), (x).end()
#define COUT(x) cout << (x) << "\\n"
#define IOS                                                                    \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);
#define REP(i, n) for (int i = 0; i < n; i++)
#define YES(x) cout << (x ? "YES" : "NO") << "\\n"
#define Yes(x) cout << (x ? "Yes" : "No") << "\\n"
#define dump(x) cout << #x << " = " << (x) << "\\n"
#define endl "\\n"
using G = vector<vector<int>>;
using M = map<int, int>;
using P = pair<int, int>;
using PQ = priority_queue<int>;
using PQG = priority_queue<int, vector<int>, greater<int>>;
using V = vector<int>;
using ll = long long;
using edge = struct {
  int to;
  int cost;
};
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 (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const int INF = 1e9;
const int MOD = 1e9 + 7;
const ll LINF = 1e18;

int main() {
  IOS;
  int n, k;
  cin >> n >> k;
  vector<int> a(n);
  REP(i, n) cin >> a[i];
  sort(ALL(a), greater<int>());

  int ng = 0, ok = a[0];
  while (abs(ok - ng) > 1) {
    int mid = (ok + ng) / 2, cnt = 0;
    REP(i, n) {
      if (k < cnt)
        break;
      if (a[i] <= mid)
        break;
      cnt += a[i] / mid;
      if (a[i] % mid == 0)
        cnt--;
    }
    if (k < cnt)
      ng = mid;
    else
      ok = mid;
  }

  COUT(ok);
  return 0;
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define ALL(x) (x).begin(), (x).end()
#define COUT(x) cout << (x) << "\\n"
#define IOS                                                                    \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);
#define REP(i, n) for (int i = 0; i < n; i++)
#define YES(x) cout << (x ? "YES" : "NO") << "\\n"
#define Yes(x) cout << (x ? "Yes" : "No") << "\\n"
#define dump(x) cout << #x << " = " << (x) << "\\n"
#define endl "\\n"
using G = vector<vector<int>>;
using M = map<int, int>;
using P = pair<int, int>;
using PQ = priority_queue<int>;
using PQG = priority_queue<int, vector<int>, greater<int>>;
using V = vector<int>;
using ll = long long;
using edge = struct {
  int to;
  int cost;
};
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 (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const int INF = 1e9;
const int MOD = 1e9 + 7;
const ll LINF = 1e18;

int main() {
  IOS;
  int n, k;
  cin >> n >> k;
  vector<int> a(n);
  REP(i, n) cin >> a[i];
  sort(ALL(a), greater<int>());

  int ng = -1, ok = a[0];
  while (abs(ok - ng) > 1) {
    int mid = (ok + ng) / 2, cnt = 0;
    REP(i, n) {
      if (k < cnt)
        break;
      if (a[i] <= mid)
        break;
      cnt += a[i] / mid;
      if (a[i] % mid == 0)
        cnt--;
    }
    if (k < cnt)
      ng = mid;
    else
      ok = mid;
  }

  COUT(ok);
  return 0;
}