Problem p02679 (C++) — buggy submission, verdict: Runtime Error

// #define NDEBUG
#include "bits/stdc++.h"
#include <array>
#include <iostream>
#include <random>
#include <string>
#include <unordered_map>
#include <unordered_set>
#ifdef _MSC_VER
#include <ppl.h>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <boost/rational.hpp>
// #include <opencv2/core.hpp>
// #include <opencv2/imgproc.hpp>
// #include <opencv2/highgui.hpp>
// #else
// #include <omp.h>
#endif

using namespace std;

#define DUMPOUT cerr
#define dump(...)                                                              \\
  DUMPOUT << "  ";                                                             \\
  DUMPOUT << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]"   \\
          << endl;                                                             \\
  DUMPOUT << "    ";                                                           \\
  dump_func(__VA_ARGS__)

using uint = unsigned;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
using pss = pair<string, string>;
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const pair<_KTy, _Ty> &m) {
  o << "{" << m.first << ", " << m.second << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const map<_KTy, _Ty> &m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const unordered_map<_KTy, _Ty> &m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const vector<_Ty> &v) {
  if (v.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const deque<_Ty> &v) {
  if (v.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const set<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream &operator<<(ostream &o, const unordered_set<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const stack<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  stack<_Ty> t(s);
  o << "{" << t.top();
  t.pop();
  while (!t.empty()) {
    o << ", " << t.top();
    t.pop();
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const list<_Ty> &l) {
  if (l.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << l.front();
  for (auto itr = ++l.begin(); itr != l.end(); ++itr) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
istream &operator>>(istream &is, pair<_KTy, _Ty> &m) {
  is >> m.first >> m.second;
  return is;
}
template <typename _Ty> istream &operator>>(istream &is, vector<_Ty> &v) {
  for (size_t t = 0; t < v.size(); t++)
    is >> v[t];
  return is;
}
template <typename _Ty> istream &operator>>(istream &is, deque<_Ty> &v) {
  for (size_t t = 0; t < v.size(); t++)
    is >> v[t];
  return is;
}
namespace aux { // print tuple
template <typename Ty, unsigned N, unsigned L> struct tp {
  static void print(ostream &os, const Ty &v) {
    os << get<N>(v) << ", ";
    tp<Ty, N + 1, L>::print(os, v);
  }
};
template <typename Ty, unsigned N> struct tp<Ty, N, N> {
  static void print(ostream &os, const Ty &v) { os << get<N>(v); }
};
} // namespace aux

template <typename... Tys>
ostream &operator<<(ostream &os, const tuple<Tys...> &t) {
  os << "{";
  aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t);
  os << "}";
  return os;
}

template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}

template <typename... Args>
std::string format(const std::string &fmt, Args... args) {
  size_t len = std::snprintf(nullptr, 0, fmt.c_str(), args...);
  std::vector<char> buf(len + 1);
  std::snprintf(&buf[0], len + 1, fmt.c_str(), args...);
  return std::string(&buf[0], &buf[0] + len);
}

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&...tail) {
  DUMPOUT << head;
  if (sizeof...(Tail) == 0) {
    DUMPOUT << " ";
  } else {
    DUMPOUT << ", ";
  }
  dump_func(move(tail)...);
}

#define PI 3.14159265358979323846
#define EPS 1e-8
#define rep(t, n) for (int t = 0; t < (n); ++t)
#define all(j) (j).begin(), (j).end()
#define SZ(j) ((int)(j).size())
#define fake false

class Timer {
public:
  double t = 0;
  Timer() {}
  static double time() {
#ifdef _MSC_VER
    return __rdtsc() / 2.8e9;
#else
    unsigned long long a, d;
    __asm__ volatile("rdtsc" : "=a"(a), "=d"(d));
    return (d << 32 | a) / 2.8e9;
#endif
  }
  void measure() { t = time() - t; }
  double elapsedMs() { return (time() - t) * 1000.0; }
} timer;

struct Xorshift {
  uint64_t x = 88172645463325252LL;
  unsigned next_int() {
    x = x ^ (x << 7);
    return x = x ^ (x >> 9);
  }
  unsigned next_int(unsigned mod) {
    x = x ^ (x << 7);
    x = x ^ (x >> 9);
    return x % mod;
  }
  unsigned next_int(unsigned l, unsigned r) {
    x = x ^ (x << 7);
    x = x ^ (x >> 9);
    return x % (r - l + 1) + l;
  }
  double next_double() { return double(next_int()) / UINT_MAX; }
} rnd;

template <typename T> void shuffle_vector(vector<T> &v, Xorshift &rnd) {
  int n = v.size();
  for (int i = n - 1; i >= 1; i--) {
    int r = rnd.next_int(i);
    swap(v[i], v[r]);
  }
}

template <typename T = int> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }

// n^e mod m
template <typename T = int> T modpow(T n, T e, T m) {
  T result = 1;
  while (e > 0) {
    if (e & 1)
      result = (result * n) % m;
    e >>= 1;
    n = (n * n) % m;
  }
  return result;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  ll N;
  cin >> N;
  vector<pll> AB_(N);
  cin >> AB_;

  if (N == 1) {
    cout << 1 << endl;
    return 0;
  }

  vector<pll> AB;
  for (int i = 0; i < N; i++) {
    if (AB_[i].first == 0 && AB_[i].second == 0)
      continue;
    AB.push_back(AB_[i]);
  }
  N = AB.size();

  if (N == 0) {
    cout << AB_.size() << endl;
    return 0;
  }

  rep(i, N) {
    ll g = gcd(AB[i].first, AB[i].second);
    AB[i].first /= g;
    AB[i].second /= g;
  }

  map<pll, int> cnt;
  rep(i, N) cnt[AB[i]]++;

  vector<pll> ps;
  for (const auto &e : cnt) {
    ll c1 = e.second;
    pll p = e.first;
    pll t(-p.second, p.first);
    if (cnt.count(t)) {
      ps.emplace_back(c1, cnt[t]);
    }
  }

  ll rem = N;
  ll prod = 1;
  ll ans = 0;
  ll MOD = 1000000007;
  for (const auto &p : ps) {
    rem -= p.first + p.second;
    ll x = (modpow(2LL, p.first, MOD) + MOD - 1) *
           (modpow(2LL, p.second, MOD) + MOD - 1) % MOD;
    ans += x * prod % MOD * modpow(2LL, rem, MOD) % MOD;
    ans %= MOD;
    prod = prod * (modpow(2LL, p.first + p.second, MOD) + MOD - x) % MOD;
  }

  cout << ((AB_.size() - AB.size()) +
           (modpow(2LL, N, MOD) + MOD + MOD - ans - 1)) %
              MOD
       << endl;

  return 0;
}

Error: 0

Fixed submission:

// #define NDEBUG
#include "bits/stdc++.h"
#include <array>
#include <iostream>
#include <random>
#include <string>
#include <unordered_map>
#include <unordered_set>
#ifdef _MSC_VER
#include <ppl.h>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <boost/rational.hpp>
// #include <opencv2/core.hpp>
// #include <opencv2/imgproc.hpp>
// #include <opencv2/highgui.hpp>
// #else
// #include <omp.h>
#endif

using namespace std;

#define DUMPOUT cerr
#define dump(...)                                                              \\
  DUMPOUT << "  ";                                                             \\
  DUMPOUT << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]"   \\
          << endl;                                                             \\
  DUMPOUT << "    ";                                                           \\
  dump_func(__VA_ARGS__)

using uint = unsigned;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
using pss = pair<string, string>;
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const pair<_KTy, _Ty> &m) {
  o << "{" << m.first << ", " << m.second << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const map<_KTy, _Ty> &m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &o, const unordered_map<_KTy, _Ty> &m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const vector<_Ty> &v) {
  if (v.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const deque<_Ty> &v) {
  if (v.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const set<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream &operator<<(ostream &o, const unordered_set<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const stack<_Ty> &s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  stack<_Ty> t(s);
  o << "{" << t.top();
  t.pop();
  while (!t.empty()) {
    o << ", " << t.top();
    t.pop();
  }
  o << "}";
  return o;
}
template <typename _Ty> ostream &operator<<(ostream &o, const list<_Ty> &l) {
  if (l.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << l.front();
  for (auto itr = ++l.begin(); itr != l.end(); ++itr) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
istream &operator>>(istream &is, pair<_KTy, _Ty> &m) {
  is >> m.first >> m.second;
  return is;
}
template <typename _Ty> istream &operator>>(istream &is, vector<_Ty> &v) {
  for (size_t t = 0; t < v.size(); t++)
    is >> v[t];
  return is;
}
template <typename _Ty> istream &operator>>(istream &is, deque<_Ty> &v) {
  for (size_t t = 0; t < v.size(); t++)
    is >> v[t];
  return is;
}
namespace aux { // print tuple
template <typename Ty, unsigned N, unsigned L> struct tp {
  static void print(ostream &os, const Ty &v) {
    os << get<N>(v) << ", ";
    tp<Ty, N + 1, L>::print(os, v);
  }
};
template <typename Ty, unsigned N> struct tp<Ty, N, N> {
  static void print(ostream &os, const Ty &v) { os << get<N>(v); }
};
} // namespace aux

template <typename... Tys>
ostream &operator<<(ostream &os, const tuple<Tys...> &t) {
  os << "{";
  aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t);
  os << "}";
  return os;
}

template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}

template <typename... Args>
std::string format(const std::string &fmt, Args... args) {
  size_t len = std::snprintf(nullptr, 0, fmt.c_str(), args...);
  std::vector<char> buf(len + 1);
  std::snprintf(&buf[0], len + 1, fmt.c_str(), args...);
  return std::string(&buf[0], &buf[0] + len);
}

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&...tail) {
  DUMPOUT << head;
  if (sizeof...(Tail) == 0) {
    DUMPOUT << " ";
  } else {
    DUMPOUT << ", ";
  }
  dump_func(move(tail)...);
}

#define PI 3.14159265358979323846
#define EPS 1e-8
#define rep(t, n) for (int t = 0; t < (n); ++t)
#define all(j) (j).begin(), (j).end()
#define SZ(j) ((int)(j).size())
#define fake false

class Timer {
public:
  double t = 0;
  Timer() {}
  static double time() {
#ifdef _MSC_VER
    return __rdtsc() / 2.8e9;
#else
    unsigned long long a, d;
    __asm__ volatile("rdtsc" : "=a"(a), "=d"(d));
    return (d << 32 | a) / 2.8e9;
#endif
  }
  void measure() { t = time() - t; }
  double elapsedMs() { return (time() - t) * 1000.0; }
} timer;

struct Xorshift {
  uint64_t x = 88172645463325252LL;
  unsigned next_int() {
    x = x ^ (x << 7);
    return x = x ^ (x >> 9);
  }
  unsigned next_int(unsigned mod) {
    x = x ^ (x << 7);
    x = x ^ (x >> 9);
    return x % mod;
  }
  unsigned next_int(unsigned l, unsigned r) {
    x = x ^ (x << 7);
    x = x ^ (x >> 9);
    return x % (r - l + 1) + l;
  }
  double next_double() { return double(next_int()) / UINT_MAX; }
} rnd;

template <typename T> void shuffle_vector(vector<T> &v, Xorshift &rnd) {
  int n = v.size();
  for (int i = n - 1; i >= 1; i--) {
    int r = rnd.next_int(i);
    swap(v[i], v[r]);
  }
}

template <typename T = int> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }

// n^e mod m
template <typename T = int> T modpow(T n, T e, T m) {
  T result = 1;
  while (e > 0) {
    if (e & 1)
      result = (result * n) % m;
    e >>= 1;
    n = (n * n) % m;
  }
  return result;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  ll N;
  cin >> N;
  vector<pll> AB(N);
  cin >> AB;

  rep(i, N) {
    ll g = gcd(AB[i].first, AB[i].second);
    AB[i].first /= g;
    AB[i].second /= g;
  }

  map<pll, int> cnt;
  rep(i, N) cnt[AB[i]]++;

  vector<pll> ps;
  for (const auto &e : cnt) {
    ll c1 = e.second;
    pll p = e.first;
    pll t(-p.second, p.first);
    if (cnt.count(t)) {
      ps.emplace_back(c1, cnt[t]);
    }
  }

  ll rem = N;
  ll prod = 1;
  ll ans = 0;
  ll MOD = 1000000007;
  for (const auto &p : ps) {
    rem -= p.first + p.second;
    ll x = (modpow(2LL, p.first, MOD) + MOD - 1) *
           (modpow(2LL, p.second, MOD) + MOD - 1) % MOD;
    ans += x * prod % MOD * modpow(2LL, rem, MOD) % MOD;
    ans %= MOD;
    prod = prod * (modpow(2LL, p.first + p.second, MOD) + MOD - x) % MOD;
  }

  cout << (modpow(2LL, N, MOD) + MOD + MOD - ans - 1) % MOD << endl;

  return 0;
}