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

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

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = mod * mod;
const int INF_N = 1e+9;
typedef pair<int, int> P;
#define stop                                                                   \\
  char nyaa;                                                                   \\
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);
// typedef vector<vector<ll>> mat;
typedef vector<int> vec;

// 繰り返し二乗法
ll mod_pow(ll a, ll n, ll m) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * a % m;
    a = a * a % m;
    n >>= 1;
  }
  return res;
}

struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

// 逆元(Eucledean algorithm)
ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 18;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}
using mP = pair<modint, modint>;

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

void solve() {
  int N, K;
  cin >> N >> K;
  vector<ll> a(N), s, t;
  rep(i, N) {
    cin >> a[i];
    if (a[i] < 0)
      t.push_back(a[i]);
    else
      s.push_back(a[i]);
  }
  bool ok = false;
  int S = s.size();
  int T = t.size();
  if (S > 0) {
    if (N == K)
      ok = (T % 2 == 0);
    else
      ok = true;
  } else {
    ok = (K % 2 == 0);
  }

  modint ans = 1;
  if (!ok) {
    sort(all(a), [](ll x, ll y) { return abs(x) < abs(y); });
    rep(i, K) ans *= modint(a[i]);
  } else {
    sort(all(s));
    sort(t.rbegin(), t.rend());
    if (K % 2 == 1) {
      ans *= modint(s.back());
      s.pop_back();
    }
    vector<ll> p;
    while (s.size() >= 2) {
      ll x = s.back();
      s.pop_back();
      x *= s.back();
      s.pop_back();
      p.push_back(x);
    }
    while (t.size() >= 2) {
      ll x = t.back();
      t.pop_back();
      x *= t.back();
      t.pop_back();
      p.push_back(x);
    }
    sort(p.rbegin(), p.rend());
    rep(i, K / 2) { ans *= modint(p[i]); }
  }
  cout << ans << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init_f();
  // init();
  // int t; cin >> t; rep(i, t)solve();
  solve();
  //   stop
  return 0;
}


Error: 0

Fixed submission:

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

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = mod * mod;
const int INF_N = 1e+9;
typedef pair<int, int> P;
#define stop                                                                   \\
  char nyaa;                                                                   \\
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);
// typedef vector<vector<ll>> mat;
typedef vector<int> vec;

// 繰り返し二乗法
ll mod_pow(ll a, ll n, ll m) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * a % m;
    a = a * a % m;
    n >>= 1;
  }
  return res;
}

struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

// 逆元(Eucledean algorithm)
ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 18;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}
using mP = pair<modint, modint>;

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

void solve() {
  ll N, K;
  cin >> N >> K;
  vector<ll> p, m, z;
  rep(i, N) {
    ll x;
    cin >> x;
    if (x > 0)
      p.push_back(x);
    else if (x < 0)
      m.push_back(x);
    else
      z.push_back(x);
  }
  if ((ll)p.size() + m.size() < K) {
    cout << 0 << endl;
    return;
  }
  sort(all(p));
  reverse(all(p));
  sort(all(m));
  deque<ll> sei, fu;
  rep(i, p.size()) { sei.push_back(p[i]); }
  rep(i, m.size()) { fu.push_back(m[i]); }
  int cnt = 0;
  modint res = 1;
  while (cnt < K) {
    if (sei.empty() || fu.empty())
      break;
    ll t1 = sei.front();
    ll t2 = fu.front();
    if (abs(t1) >= abs(t2)) {
      res *= modint(t1);
      sei.pop_front();
      cnt++;
    } else {
      if (fu.size() < 2) {
        res *= modint(t1);
        sei.pop_front();
        cnt++;
      } else {
        if (sei.size() < 2) {
          res *= modint(t2 * fu[1]);
          fu.pop_front();
          fu.pop_front();
          cnt += 2;
        } else {
          ll tt1 = t1 * sei[1];
          ll tt2 = t2 * fu[1];
          if (abs(tt1) >= abs(tt2)) {
            res *= modint(tt1);
            sei.pop_front();
            sei.pop_front();
            cnt += 2;
          } else {
            res *= modint(tt2);
            fu.pop_front();
            fu.pop_front();
            cnt += 2;
          }
        }
      }
    }
  }
  modint res2 = 1;
  auto sei2 = sei;
  auto fu2 = fu;
  rep(i, K) {
    if (sei2.empty()) {
      res2 *= modint(fu2.back());
      fu2.pop_back();
    } else if (fu2.empty()) {
      res2 *= modint(sei2.back());
      sei2.pop_back();
    } else {
      ll t1 = sei2.back();
      ll t2 = fu2.back();
      if (abs(t1) <= abs(t2)) {
        res2 *= modint(t1);
        sei2.pop_back();
      } else {
        res2 *= modint(t2);
        fu2.pop_back();
      }
    }
  }
  if (cnt != K) {
    if (fu.empty()) {
      rep(i, K - cnt) {
        res *= modint(sei.front());
        sei.pop_front();
      }
    } else {
      if ((K - cnt) % 2) {
        if (z.size()) {
          cout << 0 << endl;
          return;
        } else {
          res = res2;
        }
      }
    }
  }

  cout << res.n << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init_f();
  // init();
  // int t; cin >> t; rep(i, t)solve();
  solve();
  //   stop
  return 0;
}