Problem p02598 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
// const double pi=acos(-1.0);
#define mod 1000000007
#define forn(i, k, n) for (ll i = k; i < n; i++)
#define fornr(i, k, k1) for (ll i = k; i >= k1; i--)
#define v(ll) vector<ll>
#define vl(a, n, ll, k) vector<ll> a(n, k)
#define vli(a, n) vector<ll> a(n)
#define init(a, n)                                                             \
  vector<ll> a(n);                                                             \
  forn(i, 0, n) cin >> a[i]
#define vll(a, n, m, ll, k) vector<vector<ll>> a(n, vector<ll>(m, k))
#define mp(a, ll, ll1) map<ll, ll1> a
#define st(a, ll) set<ll> a
#define mpa make_pair
#define pr pair<ll, ll>
#define pb push_back
#define MAX 1000000
#define ed '\n'
#define fileTake                                                               \
  ifstream cin("input.txt");                                                   \
  ofstream cout("output.txt");
#define sortv(a) sort(a.begin(), a.end())
#define sorta(a, n) sort(a, a + n)
#define yeah "YES"
#define nil "NO"
#define All(x) x.begin(), x.end()
#define remDup(a) a.erase(unique(All(a)), a.end())
#define N 100

void swap(ll &x, ll &y) {
  x = x ^ y;
  y = x ^ y;
  x = x ^ y;
}

template <typename T> void print(T a) {
  for (auto i = a.begin(); i != a.end(); i++)
    cout << *i << " ";
  cout << endl;
}
bool isVowel(char c) {
  if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u')
    return true;
  return false;
}

void sync() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}

int main() {
  sync();

  ll n, k;
  cin >> n >> k;
  init(a, n);
  ll ans = -1;
  ll lo = 0, hi = 1000000000;
  while (lo <= hi) {
    ll mid = (lo + hi) / 2;
    ll cnt = 0;
    forn(i, 0, n) {
      cnt += a[i] / mid;
      if (a[i] % mid == 0)
        cnt--;
    }
    if (cnt <= k) {
      ans = mid;
      hi = mid - 1;
    } else
      lo = mid + 1;
  }
  cout << ans << endl;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
// const double pi=acos(-1.0);
#define mod 1000000007
#define forn(i, k, n) for (ll i = k; i < n; i++)
#define fornr(i, k, k1) for (ll i = k; i >= k1; i--)
#define v(ll) vector<ll>
#define vl(a, n, ll, k) vector<ll> a(n, k)
#define vli(a, n) vector<ll> a(n)
#define init(a, n)                                                             \
  vector<ll> a(n);                                                             \
  forn(i, 0, n) cin >> a[i]
#define vll(a, n, m, ll, k) vector<vector<ll>> a(n, vector<ll>(m, k))
#define mp(a, ll, ll1) map<ll, ll1> a
#define st(a, ll) set<ll> a
#define mpa make_pair
#define pr pair<ll, ll>
#define pb push_back
#define MAX 1000000
#define ed '\n'
#define fileTake                                                               \
  ifstream cin("input.txt");                                                   \
  ofstream cout("output.txt");
#define sortv(a) sort(a.begin(), a.end())
#define sorta(a, n) sort(a, a + n)
#define yeah "YES"
#define nil "NO"
#define All(x) x.begin(), x.end()
#define remDup(a) a.erase(unique(All(a)), a.end())
#define N 100

void swap(ll &x, ll &y) {
  x = x ^ y;
  y = x ^ y;
  x = x ^ y;
}

template <typename T> void print(T a) {
  for (auto i = a.begin(); i != a.end(); i++)
    cout << *i << " ";
  cout << endl;
}
bool isVowel(char c) {
  if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u')
    return true;
  return false;
}

void sync() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}

int main() {
  sync();

  ll n, k;
  cin >> n >> k;
  init(a, n);
  ll ans = -1;
  ll lo = 1, hi = 1000000000;
  while (lo <= hi) {
    ll mid = (lo + hi) / 2;
    ll cnt = 0;
    forn(i, 0, n) {
      cnt += a[i] / mid;
      if (a[i] % mid == 0)
        cnt--;
    }
    if (cnt <= k) {
      ans = mid;
      hi = mid - 1;
    } else
      lo = mid + 1;
  }
  cout << ans << endl;
}