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

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <ctime>
#include <deque>
#include <float.h>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
unsigned euclidean_gcd(unsigned a, unsigned b) {
  if (a < b)
    return euclidean_gcd(b, a);
  unsigned r;
  while ((r = a % b)) {
    a = b;
    b = r;
  }
  return b;
}

ll ll_gcd(ll a, ll b) {
  if (a < b)
    return ll_gcd(b, a);
  ll r;
  while ((r = a % b)) {
    a = b;
    b = r;
  }
  return b;
}

class UnionFind {
public:
  vector<ll> par;
  vector<ll> siz;
  UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
    for (ll i = 0; i < sz_; ++i)
      par[i] = i;
  }
  void init(ll sz_) {
    par.resize(sz_);
    siz.assign(sz_, 1LL);
    for (ll i = 0; i < sz_; ++i)
      par[i] = i;
  }
  ll root(ll x) {
    while (par[x] != x) {
      x = par[x] = par[par[x]];
    }
    return x;
  }
  bool merge(ll x, ll y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return false;
    if (siz[x] < siz[y])
      swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;
  }

  bool issame(ll x, ll y) { return root(x) == root(y); }

  ll size(ll x) { return siz[root(x)]; }
};

long long modpow(long long a, long long n, long long mod) {
  long long res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

long long modinv(long long a, long long mod) { return modpow(a, mod - 2, mod); }

vector<int> tpsort(vector<vector<int>> &G) {
  int V = G.size();
  vector<int> sorted_vertices;
  queue<int> que;
  vector<int> indegree(V);
  for (int i = 0; i < V; i++) {
    for (int j = 0; j < G[i].size(); j++) {
      indegree[G[i][j]]++;
    }
  }
  for (int i = 0; i < V; i++) {
    if (indegree[i] == 0) {
      que.push(i);
    }
  }
  while (que.empty() == false) {
    int v = que.front();
    que.pop();
    for (int i = 0; i < G[v].size(); i++) {
      int u = G[v][i];
      indegree[u] -= 1;
      if (indegree[u] == 0)
        que.push(u);
    }
    sorted_vertices.push_back(v);
  }
  return sorted_vertices;
}

struct Point {
  double x;
  double y;
};

struct LineSegment {
  Point start;
  Point end;
};

double tenkyori(const LineSegment &line, const Point &point) {
  double x0 = point.x, y0 = point.y;
  double x1 = line.start.x, y1 = line.start.y;
  double x2 = line.end.x, y2 = line.end.y;

  double a = x2 - x1;
  double b = y2 - y1;
  double a2 = a * a;
  double b2 = b * b;
  double r2 = a2 + b2;
  double tt = -(a * (x1 - x0) + b * (y1 - y0));

  if (tt < 0)
    return sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
  else if (tt > r2)
    return sqrt((x2 - x0) * (x2 - x0) + (y2 - y0) * (y2 - y0));

  double f1 = a * (y1 - y0) - b * (x1 - x0);
  return sqrt((f1 * f1) / r2);
}

int main() {
  ll n;
  cin >> n;
  ll k;
  cin >> k;
  vector<ll> z(n);
  vector<pair<ll, ll>> sr(n);
  vector<ll> mn;
  vector<ll> pl;
  for (int i = 0; i < n; i++) {
    cin >> z[i];
  }
  for (int i = 0; i < n; i++) {
    sr[i].first = abs(z[i]);
    if (z[i] < 0) {
      sr[i].second = 1;
      mn.push_back(abs(z[i]));
    } else
      pl.push_back(abs(z[i]));
  }
  sort(sr.begin(), sr.end());
  sort(mn.begin(), mn.end());
  sort(pl.begin(), pl.end());
  reverse(sr.begin(), sr.end());
  reverse(mn.begin(), mn.end());
  reverse(pl.begin(), pl.end());
  ll fl = 0;
  ll fla = 0;
  for (int i = 0; i < k; i++) {
    fl += sr[i].second;
  }
  for (int i = 0; i < n; i++) {
    fla += sr[i].second;
  }
  if (fl % 2 == 0) {
    ll ans = 1;
    for (int i = 0; i < k; i++) {
      ans *= sr[i].first;
      ans %= 1000000007;
    }
    cout << ans << endl;
  } else {
    if (n == k) {
      ll ans = 1;
      for (int i = 0; i < k; i++) {
        ans *= sr[i].first;
        ans %= 1000000007;
      }
      cout << (1000000007 - ans) % 1000000007 << endl;
    } else if (fla == n) {
      reverse(sr.begin(), sr.end());
      ll ans = 1;
      for (int i = 0; i < k; i++) {
        ans *= sr[i].first;
        ans %= 1000000007;
      }
      cout << (1000000007 - ans) % 1000000007 << endl;
    } else {
      if (mn.size() == fl) {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        ans *= pl[k - fl];
        ans %= 1000000007;
        ans *= modinv(mn[fl - 1], 1000000007);
        ans %= 1000000007;
        cout << ans << endl;
      } else if (k == fl) {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        ans *= pl[0];
        ans %= 1000000007;
        ans *= modinv(mn[fl - 1], 1000000007);
        ans %= 1000000007;
        cout << ans << endl;
      } else if (k - fl == pl.size()) {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        ans *= mn[fl];
        ans %= 1000000007;
        ans *= modinv(pl[k - fl - 1], 1000000007);
        ans %= 1000000007;
        cout << ans << endl;
      } else {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        if (pl[k - fl] * pl[k - fl - 1] > mn[fl] * mn[fl - 1]) {
          ans *= pl[k - fl];
          ans %= 1000000007;
          ans *= modinv(mn[fl - 1], 1000000007);
          ans %= 1000000007;
        } else {
          ans *= mn[fl];
          ans %= 1000000007;
          ans *= modinv(pl[k - fl - 1], 1000000007);
          ans %= 1000000007;
        }
        cout << ans << endl;
      }
    }
  }
}

Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <ctime>
#include <deque>
#include <float.h>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
unsigned euclidean_gcd(unsigned a, unsigned b) {
  if (a < b)
    return euclidean_gcd(b, a);
  unsigned r;
  while ((r = a % b)) {
    a = b;
    b = r;
  }
  return b;
}

ll ll_gcd(ll a, ll b) {
  if (a < b)
    return ll_gcd(b, a);
  ll r;
  while ((r = a % b)) {
    a = b;
    b = r;
  }
  return b;
}

class UnionFind {
public:
  vector<ll> par;
  vector<ll> siz;
  UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
    for (ll i = 0; i < sz_; ++i)
      par[i] = i;
  }
  void init(ll sz_) {
    par.resize(sz_);
    siz.assign(sz_, 1LL);
    for (ll i = 0; i < sz_; ++i)
      par[i] = i;
  }
  ll root(ll x) {
    while (par[x] != x) {
      x = par[x] = par[par[x]];
    }
    return x;
  }
  bool merge(ll x, ll y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return false;
    if (siz[x] < siz[y])
      swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;
  }

  bool issame(ll x, ll y) { return root(x) == root(y); }

  ll size(ll x) { return siz[root(x)]; }
};

long long modpow(long long a, long long n, long long mod) {
  long long res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

long long modinv(long long a, long long mod) { return modpow(a, mod - 2, mod); }

vector<int> tpsort(vector<vector<int>> &G) {
  int V = G.size();
  vector<int> sorted_vertices;
  queue<int> que;
  vector<int> indegree(V);
  for (int i = 0; i < V; i++) {
    for (int j = 0; j < G[i].size(); j++) {
      indegree[G[i][j]]++;
    }
  }
  for (int i = 0; i < V; i++) {
    if (indegree[i] == 0) {
      que.push(i);
    }
  }
  while (que.empty() == false) {
    int v = que.front();
    que.pop();
    for (int i = 0; i < G[v].size(); i++) {
      int u = G[v][i];
      indegree[u] -= 1;
      if (indegree[u] == 0)
        que.push(u);
    }
    sorted_vertices.push_back(v);
  }
  return sorted_vertices;
}

struct Point {
  double x;
  double y;
};

struct LineSegment {
  Point start;
  Point end;
};

double tenkyori(const LineSegment &line, const Point &point) {
  double x0 = point.x, y0 = point.y;
  double x1 = line.start.x, y1 = line.start.y;
  double x2 = line.end.x, y2 = line.end.y;

  double a = x2 - x1;
  double b = y2 - y1;
  double a2 = a * a;
  double b2 = b * b;
  double r2 = a2 + b2;
  double tt = -(a * (x1 - x0) + b * (y1 - y0));

  if (tt < 0)
    return sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
  else if (tt > r2)
    return sqrt((x2 - x0) * (x2 - x0) + (y2 - y0) * (y2 - y0));

  double f1 = a * (y1 - y0) - b * (x1 - x0);
  return sqrt((f1 * f1) / r2);
}

int main() {
  ll n;
  cin >> n;
  ll k;
  cin >> k;
  vector<ll> z(n);
  vector<pair<ll, ll>> sr(n);
  vector<ll> mn;
  vector<ll> pl;
  for (int i = 0; i < n; i++) {
    cin >> z[i];
  }
  for (int i = 0; i < n; i++) {
    sr[i].first = abs(z[i]);
    if (z[i] < 0) {
      sr[i].second = 1;
      mn.push_back(abs(z[i]));
    } else
      pl.push_back(abs(z[i]));
  }
  sort(sr.begin(), sr.end());
  sort(mn.begin(), mn.end());
  sort(pl.begin(), pl.end());
  reverse(sr.begin(), sr.end());
  reverse(mn.begin(), mn.end());
  reverse(pl.begin(), pl.end());
  ll fl = 0;
  ll fla = 0;
  for (int i = 0; i < k; i++) {
    fl += sr[i].second;
  }
  for (int i = 0; i < n; i++) {
    fla += sr[i].second;
  }
  if (fl % 2 == 0) {
    ll ans = 1;
    for (int i = 0; i < k; i++) {
      ans *= sr[i].first;
      ans %= 1000000007;
    }
    cout << ans << endl;
  } else {
    if (n == k) {
      ll ans = 1;
      for (int i = 0; i < k; i++) {
        ans *= sr[i].first;
        ans %= 1000000007;
      }
      cout << (1000000007 - ans) % 1000000007 << endl;
    } else if (fla == n) {
      reverse(sr.begin(), sr.end());
      ll ans = 1;
      for (int i = 0; i < k; i++) {
        ans *= sr[i].first;
        ans %= 1000000007;
      }
      cout << (1000000007 - ans) % 1000000007 << endl;
    } else {
      if (mn.size() == fl) {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        ans *= pl[k - fl];
        ans %= 1000000007;
        ans *= modinv(mn[fl - 1], 1000000007);
        ans %= 1000000007;
        cout << ans << endl;
      } else if (k - fl == pl.size()) {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        ans *= mn[fl];
        ans %= 1000000007;
        ans *= modinv(pl[k - fl - 1], 1000000007);
        ans %= 1000000007;
        cout << ans << endl;
      } else {
        ll ans = 1;
        for (int i = 0; i < k; i++) {
          ans *= sr[i].first;
          ans %= 1000000007;
        }
        if (pl[k - fl] * pl[k - fl - 1] > mn[fl] * mn[fl - 1]) {
          ans *= pl[k - fl];
          ans %= 1000000007;
          ans *= modinv(mn[fl - 1], 1000000007);
          ans %= 1000000007;
        } else {
          ans *= mn[fl];
          ans %= 1000000007;
          ans *= modinv(pl[k - fl - 1], 1000000007);
          ans %= 1000000007 + sr[10000000].first;
        }
        cout << ans << endl;
      }
    }
  }
}