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

// #define _GLIBCXX_DEBUG

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

#define endl '\\n'
#define lfs cout << fixed << setprecision(10)
#define ALL(a) (a).begin(), (a).end()
#define ALLR(a) (a).rbegin(), (a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i, n, m) for (ll i = (n); i < (ll)(m); i++)
#define rrep(i, n, m) for (ll i = (ll)(m)-1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9 + 7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template <typename T1, typename T2> bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  } else
    return false;
}
template <typename T1, typename T2> bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  } else
    return false;
}
ll median(ll a, ll b, ll c) {
  return a + b + c - max({a, b, c}) - min({a, b, c});
}
void ans1(bool x) {
  if (x)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
void ans2(bool x) {
  if (x)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
void ans3(bool x) {
  if (x)
    cout << "Yay!" << endl;
  else
    cout << ":(" << endl;
}
template <typename T1, typename T2> void ans(bool x, T1 y, T2 z) {
  if (x)
    cout << y << endl;
  else
    cout << z << endl;
}
template <typename T> void debug(vector<vector<T>> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    cout << v[i][0];
    for (ll j = 1; j < w; j++)
      cout spa v[i][j];
    cout << endl;
  }
};
void debug(vector<string> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w; j++)
      cout << v[i][j];
    cout << endl;
  }
};
template <typename T> void debug(vector<T> &v, ll n) {
  if (n != 0)
    cout << v[0];
  for (ll i = 1; i < n; i++)
    cout spa v[i];
  cout << endl;
};
template <typename T> vector<vector<T>> vec(ll x, ll y, T w) {
  vector<vector<T>> v(x, vector<T>(y, w));
  return v;
}
ll gcd(ll x, ll y) {
  ll r;
  while (y != 0 && (r = x % y) != 0) {
    x = y;
    y = r;
  }
  return y == 0 ? x : y;
}
vector<ll> dx = {1, -1, 0, 0, 1, 1, -1, -1};
vector<ll> dy = {0, 0, 1, -1, 1, -1, 1, -1};
template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << p.first << " " << p.second;
}
// mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
template <int mod> struct ModInt {
  int x;

  ModInt() : x(0) {}

  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }

  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }

  ModInt operator-() const { return ModInt(-x); }

  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

  bool operator==(const ModInt &p) const { return x == p.x; }

  bool operator!=(const ModInt &p) const { return x != p.x; }

  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }

  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }

  static int get_mod() { return mod; }
};
using modint = ModInt<MOD1>;
modint pow(ll n, ll x) { return modint(n).pow(x); }
modint pow(modint n, ll x) { return n.pow(x); }
// using modint=ld;
int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res = 0, buf = 0;
  bool judge = true;
  ll n, k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i, 0, n) cin >> a[i];
  vector<ll> b, c;
  rep(i, 0, n) {
    if (a[i] >= 0)
      b.PB(a[i]);
    else
      c.PB(a[i]);
  }
  sort(ALLR(b));
  sort(ALL(c));
  ll ib = 0, ic = 0;
  modint ret = 1;
  rep(i, 0, k) {
    if (ic == c.size() || (ib != b.size() && b[ib] >= abs(c[ic]))) {
      ret *= b[ib++];
    } else {
      ret *= abs(c[ic++]);
    }
  }
  // cout<<ret<<endl;
  if (ic % 2 == 0 || (ib > 0 && b[ib - 1] == 0) || k == n) {
    if (k == n && ic & 1)
      cout << -ret << endl;
    else
      cout << ret << endl;
  } else if (b.size() == 0) {
    sort(ALLR(c));
    ret = 1;
    rep(i, 0, k) ret *= c[i];
    cout << ret << endl;
  } else {
    // cout<<ib spa ic spa b.size() spa c.size() spa ret<<endl;
    if (ib == 0 || ic == c.size()) {
      cout << ret / abs(c[ic - 1]) * b[ib] << endl;
      ;
    } else if (ib == b.size()) {
      cout << ret * abs(c[ic]) / b[ib - 1] << endl;
    } else {
      if (b[ib - 1] * b[ib] > c[ic - 1] * c[ic])
        cout << ret / abs(c[ic - 1]) * b[ib] << endl;
      else
        cout << ret / b[ib - 1] * abs(c[ic]) << endl;
    }
  }
  return 0;
}

Error: 0

Fixed submission:

// #define _GLIBCXX_DEBUG

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

#define endl '\\n'
#define lfs cout << fixed << setprecision(10)
#define ALL(a) (a).begin(), (a).end()
#define ALLR(a) (a).rbegin(), (a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i, n, m) for (ll i = (n); i < (ll)(m); i++)
#define rrep(i, n, m) for (ll i = (ll)(m)-1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9 + 7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template <typename T1, typename T2> bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  } else
    return false;
}
template <typename T1, typename T2> bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  } else
    return false;
}
ll median(ll a, ll b, ll c) {
  return a + b + c - max({a, b, c}) - min({a, b, c});
}
void ans1(bool x) {
  if (x)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
void ans2(bool x) {
  if (x)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
void ans3(bool x) {
  if (x)
    cout << "Yay!" << endl;
  else
    cout << ":(" << endl;
}
template <typename T1, typename T2> void ans(bool x, T1 y, T2 z) {
  if (x)
    cout << y << endl;
  else
    cout << z << endl;
}
template <typename T> void debug(vector<vector<T>> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    cout << v[i][0];
    for (ll j = 1; j < w; j++)
      cout spa v[i][j];
    cout << endl;
  }
};
void debug(vector<string> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w; j++)
      cout << v[i][j];
    cout << endl;
  }
};
template <typename T> void debug(vector<T> &v, ll n) {
  if (n != 0)
    cout << v[0];
  for (ll i = 1; i < n; i++)
    cout spa v[i];
  cout << endl;
};
template <typename T> vector<vector<T>> vec(ll x, ll y, T w) {
  vector<vector<T>> v(x, vector<T>(y, w));
  return v;
}
ll gcd(ll x, ll y) {
  ll r;
  while (y != 0 && (r = x % y) != 0) {
    x = y;
    y = r;
  }
  return y == 0 ? x : y;
}
vector<ll> dx = {1, -1, 0, 0, 1, 1, -1, -1};
vector<ll> dy = {0, 0, 1, -1, 1, -1, 1, -1};
template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << p.first << " " << p.second;
}
// mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
template <int mod> struct ModInt {
  int x;

  ModInt() : x(0) {}

  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }

  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }

  ModInt operator-() const { return ModInt(-x); }

  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

  bool operator==(const ModInt &p) const { return x == p.x; }

  bool operator!=(const ModInt &p) const { return x != p.x; }

  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }

  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }

  static int get_mod() { return mod; }
};
using modint = ModInt<MOD1>;
modint pow(ll n, ll x) { return modint(n).pow(x); }
modint pow(modint n, ll x) { return n.pow(x); }
// using modint=ld;
int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res = 0, buf = 0;
  bool judge = true;
  ll n, k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i, 0, n) cin >> a[i];
  vector<ll> b, c;
  rep(i, 0, n) {
    if (a[i] >= 0)
      b.PB(a[i]);
    else
      c.PB(a[i]);
  }
  sort(ALLR(b));
  sort(ALL(c));
  ll ib = 0, ic = 0;
  modint ret = 1;
  rep(i, 0, k) {
    if (ic == c.size() || (ib != b.size() && b[ib] >= abs(c[ib]))) {
      ret *= b[ib++];
    } else {
      ret *= c[ic++];
    }
  }
  if (ic % 2 == 0 || (ib > 0 && b[ib - 1] == 0) || k == n) {
    cout << ret << endl;
  } else if (b.size() == 0) {
    sort(ALLR(c));
    ret = 1;
    rep(i, 0, k) ret *= c[i];
    cout << ret << endl;
  } else {
    if (ib == 0 || ic == c.size()) {
      cout << ret / c[ic - 1] * b[ib];
    } else if (ib == b.size()) {
      cout << ret * abs(c[ic]) / b[ib - 1] << endl;
    } else {
      if (b[ib - 1] * b[ib] > c[ic - 1] * c[ic])
        cout << ret / c[ic - 1] * b[ib] << endl;
      else
        cout << ret / b[ib - 1] * c[ic] << endl;
    }
  }
  return 0;
}