Problem p02616 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

#define FLASH                                                                  \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL);
#define ll long long int
#define MAX 1e9
#define MIN -1e9
#define mod 1000000007
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << '=' << (x) << endl;
#define mxn 300005
using namespace std;
ll domod(ll a, ll b) {
  a = (a * b) % mod;
  while (a < 0)
    a += mod;
  return a;
}
int main() {
  FLASH
  ll n, k, ans = 1;
  cin >> n >> k;
  vector<ll> po, ne;
  for (int i = 0; i < n; i++) {
    ll x;
    cin >> x;
    if (x > 0) {
      po.pb(x);
    } else {
      ne.pb(x);
    }
  }
  ll nn = po.size(), mm = ne.size(), pos, neg;
  neg = 0, pos = nn;
  sort(all(po));
  reverse(all(po));
  sort(all(ne));
  if (k == n) {
    for (int i = 0; i < (int)po.size(); i++)
      ans = domod(ans, po[i]);
    for (int i = 0; i < (int)ne.size(); i++)
      ans = domod(ans, ne[i]);
    cout << ans << '\\n';
    return 0;
  }
  if (nn == 0) {
    if (k % 2 == 1)
      reverse(all(ne));
    for (int i = 0; i < k; i++)
      ans = domod(ans, ne[i]);
    cout << ans << '\\n';
    return 0;
  }
  pos = min(nn, k);
  neg = k - pos;
  if (neg % 2 == 1 && neg + 1 <= mm) {
    pos--;
    neg++;
  }
  while (neg + 1 <= mm - 1 && pos - 2 >= 0 &&
         ne[neg] * ne[neg + 1] > po[pos - 1] * po[pos - 2]) {
    neg += 2;
    pos -= 2;
  }
  for (int i = 0; i < pos; i++)
    ans = domod(ans, po[i]);
  for (int i = 0; i < neg; i++)
    ans = domod(ans, ne[i]);
  cout << ans << '\\n';
  return 0;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>

#define FLASH                                                                  \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL);
#define ll long long int
#define MAX 1e9
#define MIN -1e9
#define mod 1000000007
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << '=' << (x) << endl;
#define mxn 300005
using namespace std;
ll domod(ll a, ll b) {
  a = (a * b) % mod;
  a += mod;
  a %= mod;
  return a;
}
int main() {
  FLASH
  ll n, k, ans = 1;
  cin >> n >> k;
  vector<ll> po, ne;
  for (int i = 0; i < n; i++) {
    ll x;
    cin >> x;
    if (x > 0) {
      po.pb(x);
    } else {
      ne.pb(x);
    }
  }
  ll nn = po.size(), mm = ne.size(), pos, neg;
  neg = 0, pos = nn;
  sort(all(po));
  reverse(all(po));
  sort(all(ne));
  if (k == n) {
    for (int i = 0; i < po.size(); i++)
      ans = domod(ans, po[i]);
    for (int i = 0; i < ne.size(); i++)
      ans = domod(ans, ne[i]);
    cout << ans << '\\n';
    return 0;
  }
  if (nn == 0) {
    reverse(all(ne));
    for (int i = 0; i < k; i++)
      ans = domod(ans, ne[i]);
    cout << ans << '\\n';
    return 0;
  }
  pos == min(nn, k);
  neg = k - pos;
  if (neg % 2 == 1 && neg + 1 <= mm - 1) {
    pos--;
    neg++;
  }
  while (neg + 1 <= mm - 1 && pos - 2 >= 0 &&
         ne[neg] * ne[neg + 1] > po[pos - 1] * po[pos - 2]) {
    neg += 2;
    pos -= 2;
  }
  for (int i = 0; i < pos; i++)
    ans = domod(ans, po[i]);
  for (int i = 0; i < neg; i++) {
    ans = domod(ans, ne[i]);
  }
  cout << ans << '\\n';
  return 0;
}