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

#include <algorithm>
#include <assert.h>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = ll(a); i < ll(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define rrep(i, a) for (ll i = ll(a - 1); i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define PRINT(V) cout << V << "\\n"
#define SORT(V) sort((V).begin(), (V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
using ull = unsigned long long;
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;
}
inline void Yes(bool condition) {
  if (condition)
    PRINT("Yes");
  else
    PRINT("No");
}
template <class itr> void cins(itr first, itr last) {
  for (auto i = first; i != last; i++) {
    cin >> (*i);
  }
}
template <class itr> void array_output(itr start, itr goal) {
  string ans = "", k = " ";
  for (auto i = start; i != goal; i++)
    ans += to_string(*i) + k;
  if (!ans.empty())
    ans.pop_back();
  PRINT(ans);
}
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }

const ll INF = 1e18;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll MOD3 = 1e6;
const ll EPS = 1e-10;
int sgn(const double a) { return (a < -EPS ? -1 : (a > EPS ? +1 : 0)); }
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> tri;
typedef pair<long double, long double> point;
typedef complex<long double> Point;
const ll MAX = 1e9;
constexpr ll nx[4] = {-1, 0, 1, 0};
constexpr ll ny[4] = {0, 1, 0, -1};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, k, plus = 0, zero = 0, minus = 0;
  cin >> n >> k;
  vector<P> num;
  rep(i, n) {
    ll a;
    cin >> a;
    if (a > 0) {
      plus++;
      num.push_back(P(a, 1));
    } else if (a == 0) {
      zero++;
    } else {
      minus++;
      num.push_back(P(-a, -1));
    }
  }
  if ((plus > 0 || k % 2 == 0) && minus / 2 * 2 + plus >= k) {
    ll cnt = 0, rm, rm1 = INF, rm2 = INF;
    queue<ll> p, m;
    RSORT(num);
    rep(i, k) {
      ll t, s;
      tie(t, s) = num[i];
      if (s == 1) {
        p.push(t);
        chmin(rm1, t);
      } else {
        m.push(t);
        chmin(rm2, t);
        cnt++;
      }
    }
    ll f = 0;
    ll ans = 1;
    if (cnt % 2) {
      ll rp1 = -1, rp2 = -1;
      rep(i, k, num.size()) {
        ll t, s;
        tie(t, s) = num[i];
        if (s == 1) {
          chmax(rp2, t);
        } else {
          chmax(rp1, t);
        }
      }
      if (rp1 == -1 || rm1 == INF) {
        f = -1;
        ans = rp2;
        rm = rm2;
      } else if (rp2 == -1 || rm2 == INF) {
        f = 1;
        ans = rp1;
        rm = rm1;
      } else {
        if (rp1 * rm2 >= rp2 * rm1) {
          f = 1;
          ans = rp1;
          rm = rm1;
        } else {
          f = -1;
          ans = rp2;
          rm = rm2;
        }
      }
    }
    while (!p.empty()) {
      if (f == 1 && p.front() == rm) {
        f = 0;
        p.pop();
      } else {
        (ans *= p.front()) %= MOD;
        p.pop();
      }
    }
    while (!m.empty()) {
      if (f == -1 && m.front() == rm) {
        f = 0;
        m.pop();
      } else {
        (ans *= m.front()) %= MOD;
        m.pop();
      }
    }
    PRINT(ans);
  } else if (zero > 0) {
    PRINT(0);
  } else {
    SORT(num);
    ll ans = 1;
    rep(i, k) { (ans *= num[i].first) %= MOD; }
    PRINT(MOD - ans % MOD);
  }
}

Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = ll(a); i < ll(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define PRINT(V) cout << V << "\\n"
#define SORT(V) sort((V).begin(), (V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
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;
}
inline void Yes(bool condition) {
  if (condition)
    PRINT("Yes");
  else
    PRINT("No");
}
template <class itr> void cins(itr first, itr last) {
  for (auto i = first; i != last; i++) {
    cin >> (*i);
  }
}
template <class itr> void array_output(itr start, itr goal) {
  string ans = "", k = " ";
  for (auto i = start; i != goal; i++)
    ans += to_string(*i) + k;
  if (!ans.empty())
    ans.pop_back();
  PRINT(ans);
}
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }
const ll INF = 1e15;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
typedef pair<ll, ll> P;
typedef pair<double, double> point;
const ll MAX = 500005;
constexpr ll nx[8] = {1, 0, -1, 0, 1, -1, 1, -1};
constexpr ll ny[8] = {0, 1, 0, -1, 1, 1, -1, -1};
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, k;
  cin >> n >> k;
  vector<ll> plus, minus, al;
  ll p = 0, m = 0, a, zero = 0;
  rep(i, n) {
    cin >> a;
    if (a > 0)
      plus.push_back(a);
    else if (a == 0)
      zero++;
    else
      minus.push_back(-a);
    al.push_back(abs(a));
  }
  p = plus.size();
  m = minus.size();
  RSORT(plus);
  RSORT(minus);
  ll ind = 0;
  for (ll i = 0; i <= min(m - 2, k); i += 2) {
    if (i + p < k)
      continue;
    ll s = k - i;
    if (s > p - 2) {
      ind = i + 2;
      continue;
    }
    if (plus[s] * plus[s + 1] < minus[i] * minus[i + 1]) {
      ind = i + 2;
    } else
      break;
  }
  if (m / 2 * 2 + p < k) {
    SORT(al);
    ll ans = 1;
    rep(i, k) { (ans *= al[i]) %= MOD; }
    PRINT((MOD - ans) % MOD);
    return 0;
  } else {
    ll ans = 1;
    rep(i, ind) { (ans *= minus[i]) %= MOD; }
    rep(i, k - ind) { (ans *= plus[i]) %= MOD; }
    PRINT(ans);
  }
}