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

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
#define rep(i, n) for (ll i = 0; i < n; i++)
#define FOR(i, a, b) for (ll i = a; i < b; i++)
#define fi first
#define se second
#define endl "\\n"

template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> ostream &operator<<(ostream &s, const complex<T> &d) {
  return s << "(" << d.real() << ", " << d.imag() << ")";
}
template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &d) {
  return s << "(" << d.first << ", " << d.second << ")";
}
template <typename T> ostream &operator<<(ostream &s, const vector<T> &d) {
  int len = d.size();
  rep(i, len) {
    s << d[i];
    if (i < len - 1)
      s << " ";
  }
  return s;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &d) {
  int len = d.size();
  rep(i, len) { s << d[i] << endl; }
  return s;
}
template <typename T> ostream &operator<<(ostream &s, const set<T> &v) {
  s << "{ ";
  for (auto itr = v.begin(); itr != v.end(); ++itr) {
    if (itr != v.begin()) {
      s << ", ";
    }
    s << (*itr);
  }
  s << " }";
  return s;
}
template <typename T> ostream &operator<<(ostream &s, const multiset<T> &v) {
  s << "{ ";
  for (auto itr = v.begin(); itr != v.end(); ++itr) {
    if (itr != v.begin()) {
      s << ", ";
    }
    s << (*itr);
  }
  s << " }";
  return s;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &s, const map<T1, T2> &m) {
  s << "{" << endl;
  for (auto itr = m.begin(); itr != m.end(); ++itr) {
    s << " " << (*itr).first << " : " << (*itr).second << endl;
  }
  s << "}" << endl;
  return s;
}

const ll mod = 1e9 + 7;
const ll inf = 1e17;
const int INF = 1e9;
const double EPS = 1e-10;
const double PI = acos(-1);

struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  friend ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }
  friend istream &operator>>(istream &is, mint &a) {
    ll t;
    is >> t;
    a = mint(t);
    return (is);
  }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; i++)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; i--)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, k;
  cin >> n >> k;
  deque<ll> a(n);
  vector<ll> cnt(3, 0);
  rep(i, n) {
    cin >> a[i];
    if (a[i] > 0)
      cnt[0]++;
    else if (a[i] == 0)
      cnt[1]++;
    else
      cnt[2]++;
  }
  mint ans = 1;
  sort(begin(a), end(a), greater<ll>());
  ll num = cnt[0] + cnt[2] / 2 * 2;
  if (cnt[2] <= 1) { // 負の数が1個以下の場合は正の数大きい方からとる
    rep(i, k) { ans *= a[i]; }
    cout << ans << endl;
    return 0;
  }
  if (cnt[0] == 0) { // 正の数が0個数の時
    if (k % 2) {
      rep(i, k) ans *= a[i];
      cout << ans << endl;
      return 0;
    } else {
      sort(begin(a), end(a));
      rep(i, k) ans *= a[i];
      cout << ans << endl;
      return 0;
    }
  }
  if (num < k) {
    if (cnt[1])
      cout << 0 << endl;
    else {
      rep(i, k) { ans *= a[i]; }
      cout << ans << endl;
    }
    return 0;
  }
  // 他は0になることはない
  if (k % 2) {
    ans = a[0];
    k--;
    a.pop_front();
  }
  vector<ll> b;
  rep(i, n) {
    if (a[i] != 0)
      b.push_back(a[i]);
  }
  n = b.size();
  sort(begin(b), end(b), greater<ll>());
  priority_queue<ll, vector<ll>, greater<ll>> que;
  for (int i = 0; i + 1 < n; i += 2) {
    if (b[i] > 0 && b[i + 1] > 0) {
      que.push(b[i] * b[i + 1]);
    } else {
      break;
    }
    if (que.size() == k / 2)
      break;
  }
  for (int i = n - 1; i >= 1; i -= 2) {
    if (b[i] > 0 || b[i - 1] > 0)
      break;
    if (que.size() < k / 2) {
      que.push(b[i] * b[i - 1]);
    } else {
      ll x = que.top();
      if (x < b[i] * b[i - 1]) {
        que.pop();
        que.push(b[i] * b[i - 1]);
      }
    }
  }
  if (que.size() == k / 2) {
    while (!que.empty()) {
      ans *= que.top();
      que.pop();
    }
  } else {
    rep(i, k) { ans *= b[i]; }
  }
  cout << ans << endl;
}

Error: -6
bab1b603-7268-42c2-9638-1179ff18eb7f.out: /home/alex/Documents/bug-detection/input/Project_CodeNet/data/p02616/C++/s707222394.cpp:115: int main(): Assertion `cnt[2]<=1 || cnt[0]==0 || num<k' failed.


Fixed submission:

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
#define rep(i, n) for (ll i = 0; i < n; i++)
#define FOR(i, a, b) for (ll i = a; i < b; i++)
#define fi first
#define se second
#define endl "\\n"

template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> ostream &operator<<(ostream &s, const complex<T> &d) {
  return s << "(" << d.real() << ", " << d.imag() << ")";
}
template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &d) {
  return s << "(" << d.first << ", " << d.second << ")";
}
template <typename T> ostream &operator<<(ostream &s, const vector<T> &d) {
  int len = d.size();
  rep(i, len) {
    s << d[i];
    if (i < len - 1)
      s << " ";
  }
  return s;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &d) {
  int len = d.size();
  rep(i, len) { s << d[i] << endl; }
  return s;
}
template <typename T> ostream &operator<<(ostream &s, const set<T> &v) {
  s << "{ ";
  for (auto itr = v.begin(); itr != v.end(); ++itr) {
    if (itr != v.begin()) {
      s << ", ";
    }
    s << (*itr);
  }
  s << " }";
  return s;
}
template <typename T> ostream &operator<<(ostream &s, const multiset<T> &v) {
  s << "{ ";
  for (auto itr = v.begin(); itr != v.end(); ++itr) {
    if (itr != v.begin()) {
      s << ", ";
    }
    s << (*itr);
  }
  s << " }";
  return s;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &s, const map<T1, T2> &m) {
  s << "{" << endl;
  for (auto itr = m.begin(); itr != m.end(); ++itr) {
    s << " " << (*itr).first << " : " << (*itr).second << endl;
  }
  s << "}" << endl;
  return s;
}

const ll mod = 1e9 + 7;
const ll inf = 1e17;
const int INF = 1e9;
const double EPS = 1e-10;
const double PI = acos(-1);

struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  friend ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }
  friend istream &operator>>(istream &is, mint &a) {
    ll t;
    is >> t;
    a = mint(t);
    return (is);
  }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; i++)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; i--)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, k;
  cin >> n >> k;
  vector<ll> a(n);
  vector<ll> cnt(3, 0);
  rep(i, n) {
    cin >> a[i];
    if (a[i] > 0)
      cnt[0]++;
    else if (a[i] == 0)
      cnt[1]++;
    else
      cnt[2]++;
  }
  mint ans = 1;
  sort(begin(a), end(a), greater<ll>());
  ll num = cnt[0] + cnt[2] / 2 * 2;
  assert(cnt[2] <= 1 || cnt[0] == 0 || num < k);
  if (cnt[2] <= 1) { // 負の数が1個以下の場合は正の数大きい方からとる
    rep(i, k) { ans *= a[i]; }
    cout << ans << endl;
    return 0;
  }
  if (cnt[0] == 0) { // 正の数が0個数の時
    if (k % 2) {
      rep(i, k) ans *= a[i];
      cout << ans << endl;
      return 0;
    } else {
      sort(begin(a), end(a));
      rep(i, k) ans *= a[i];
      cout << ans << endl;
      return 0;
    }
  }
  if (num < k) {
    if (cnt[1])
      cout << 0 << endl;
    else {
      rep(i, k) { ans *= a[i]; }
      cout << ans << endl;
    }
    return 0;
  }
  // 他は0になることはない
  vector<ll> b;
  rep(i, n) {
    if (a[i] != 0)
      b.push_back(a[i]);
  }
  n = b.size();
  sort(begin(b), end(b), greater<ll>());
  priority_queue<ll, vector<ll>, greater<ll>> que;
  rep(i, k) {
    if (b[i] > 0)
      que.push(b[i]);
  }
  if ((k - que.size()) % 2) {
    que.pop();
  }
  for (int i = n - 1; i >= 1; i -= 2) {
    if (que.size() < k) {
      que.push(-b[i]);
      que.push(-b[i - 1]);
    } else {
      ll n1 = que.top();
      que.pop();
      ll n2 = que.top();
      que.pop();
      if (n1 * n2 < b[i] * b[i - 1]) {
        que.push(b[i]);
        que.push(b[i - 1]);
      } else {
        que.push(n1);
        que.push(n2);
      }
    }
  }
  while (!que.empty()) {
    ans *= que.top();
    que.pop();
  }
  cout << ans << endl;
}