Problem p02883 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = (int)(0); i < (int)(n); ++i)
#define reps(i, n) for (int i = (int)(1); i <= (int)(n); ++i)
#define rrep(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rreps(i, n) for (int i = ((int)(n)); i > 0; i--)
#define irep(i, m, n) for (int i = (int)(m); i < (int)(n); ++i)
#define ireps(i, m, n) for (int i = (int)(m); i <= (int)(n); ++i)
#define FOR(e, c) for (auto &e : c)
#define SORT(v, n) sort(v, v + n);
#define vsort(v) sort(v.begin(), v.end());
#define rvisort(v) sort(v.begin(), v.end(), greater<int>());
#define all(v) v.begin(), v.end()
#define mp(n, m) make_pair(n, m);
#define cout(d) cout << d << endl;
#define coutd(d) cout << std::setprecision(10) << d << endl;
#define cinline(n) getline(cin, n);
#define replace_all(s, b, a) replace(s.begin(), s.end(), b, a);
// #define int long long
#define PI (acos(-1))
#define FILL(v, n, x) fill(v, v + n, x);

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using ul = unsigned long;

const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll LINF = 1e18;

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;
}

int GCD(int a, int b) { return b ? GCD(b, a % b) : a; }
int LCM(int a, int b) { return a * b / GCD(a, b); }

signed main() {
  int n, k;
  cin >> n >> k;
  vi a(n);
  vi f(n);
  rep(i, n) cin >> a[i];
  rep(i, n) cin >> f[i];

  vsort(a);
  rvisort(f);

  ll l = -1, r = 1e12;
  while (l + 1 < r) {
    ll c = (l + r) / 2;
    bool ok = [&]() {
      ll s = 0;
      rep(i, n) { s += max(0ll, a[i] - c / f[i]); }
      return s <= k;
    }();
    if (ok)
      r = c;
    else
      l = c;
  }
  cout << r << endl;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = (int)(0); i < (int)(n); ++i)
#define reps(i, n) for (int i = (int)(1); i <= (int)(n); ++i)
#define rrep(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rreps(i, n) for (int i = ((int)(n)); i > 0; i--)
#define irep(i, m, n) for (int i = (int)(m); i < (int)(n); ++i)
#define ireps(i, m, n) for (int i = (int)(m); i <= (int)(n); ++i)
#define FOR(e, c) for (auto &e : c)
#define SORT(v, n) sort(v, v + n);
#define vsort(v) sort(v.begin(), v.end());
#define rvisort(v) sort(v.begin(), v.end(), greater<int>());
#define all(v) v.begin(), v.end()
#define mp(n, m) make_pair(n, m);
#define cout(d) cout << d << endl;
#define coutd(d) cout << std::setprecision(10) << d << endl;
#define cinline(n) getline(cin, n);
#define replace_all(s, b, a) replace(s.begin(), s.end(), b, a);
// #define int long long
#define PI (acos(-1))
#define FILL(v, n, x) fill(v, v + n, x);

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using ul = unsigned long;

const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll LINF = 1e18;

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;
}

int GCD(int a, int b) { return b ? GCD(b, a % b) : a; }
int LCM(int a, int b) { return a * b / GCD(a, b); }

signed main() {
  ll n, k;
  cin >> n >> k;
  vi a(n);
  vi f(n);
  rep(i, n) cin >> a[i];
  rep(i, n) cin >> f[i];

  vsort(a);
  rvisort(f);

  ll l = -1, r = 1e12;
  while (l + 1 < r) {
    ll c = (l + r) / 2;
    bool ok = [&]() {
      ll s = 0;
      rep(i, n) { s += max(0ll, a[i] - c / f[i]); }
      return s <= k;
    }();
    if (ok)
      r = c;
    else
      l = c;
  }
  cout << r << endl;
}