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

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define all(x) (x).begin(), (x).end()
#define uniq(v) (v).erase(unique(all(v)), (v).end())
#define sz(x) (int)((x).size())
#define fr first
#define sc second
#define pii pair<int, int>
#define rep(i, a, b) for (int i = a; i < b; i++)
#define mem1(a) memset(a, -1, sizeof(a))
#define mem0(a) memset(a, 0, sizeof(a))
#define ppc __builtin_popcount
#define ppcll __builtin_popcountll

template <typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &a) {
  in >> a.fr >> a.sc;
  return in;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &out, pair<T1, T2> a) {
  out << a.fr << " " << a.sc;
  return out;
}
template <typename T, typename T1> T amax(T &a, T1 b) {
  if (b > a)
    a = b;
  return a;
}
template <typename T, typename T1> T amin(T &a, T1 b) {
  if (b < a)
    a = b;
  return a;
}

const long long INF = 1e18;
const int32_t M = 1e9 + 7;
const int32_t MM = 998244353;

const int N = 2e5 + 5;

const int32_t MOD = M;
struct mod_int {
  int32_t val;
  mod_int(long long v = 0) {
    if (v < 0)
      v = v % MOD + MOD;
    if (v >= MOD)
      v %= MOD;
    val = v;
  }

  static int32_t mod_inv(int32_t a, int32_t m = MOD) {
    int32_t g = m, r = a, x = 0, y = 1;
    while (r != 0) {
      int32_t q = g / r;
      g %= r;
      swap(g, r);
      x -= q * y;
      swap(x, y);
    }
    return x < 0 ? x + m : x;
  }
  static unsigned fast_mod(uint64_t x, unsigned m = MOD) {
#if !defined(_WIN32) || defined(_WIN64)
    return x % m;
#endif
    unsigned x_high = x >> 32, x_low = (unsigned)x;
    unsigned quot, rem;
    asm("divl %4\\n" : "=a"(quot), "=d"(rem) : "d"(x_high), "a"(x_low), "r"(m));
    return rem;
  }

  explicit operator int() const { return val; }
  mod_int &operator+=(const mod_int &other) {
    val += other.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  mod_int &operator-=(const mod_int &other) {
    val -= other.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  mod_int &operator*=(const mod_int &other) {
    val = fast_mod((uint64_t)val * other.val);
    return *this;
  }
  mod_int &operator/=(const mod_int &other) { return *this *= other.inv(); }
  friend mod_int operator+(const mod_int &a, const mod_int &b) {
    return mod_int(a) += b;
  }
  friend mod_int operator-(const mod_int &a, const mod_int &b) {
    return mod_int(a) -= b;
  }
  friend mod_int operator*(const mod_int &a, const mod_int &b) {
    return mod_int(a) *= b;
  }
  friend mod_int operator/(const mod_int &a, const mod_int &b) {
    return mod_int(a) /= b;
  }
  mod_int &operator++() {
    val = val == MOD - 1 ? 0 : val + 1;
    return *this;
  }
  mod_int &operator--() {
    val = val == 0 ? MOD - 1 : val - 1;
    return *this;
  }
  mod_int operator++(int32_t) {
    mod_int before = *this;
    ++*this;
    return before;
  }
  mod_int operator--(int32_t) {
    mod_int before = *this;
    --*this;
    return before;
  }
  mod_int operator-() const { return val == 0 ? 0 : MOD - val; }
  bool operator==(const mod_int &other) const { return val == other.val; }
  bool operator!=(const mod_int &other) const { return val != other.val; }
  mod_int inv() const { return mod_inv(val); }
  friend ostream &operator<<(ostream &stream, const mod_int &m) {
    return stream << m.val;
  }
  friend istream &operator>>(istream &stream, mod_int &m) {
    return stream >> m.val;
  }

  mod_int pow(long long p) const {
    assert(p >= 0);
    mod_int a = *this, result = 1;
    while (p > 0) {
      if (p & 1)
        result *= a;

      a *= a;
      p >>= 1;
    }
    return result;
  }
};

map<pii, int> m;

void solve() {
  int n;
  cin >> n;
  int zc = 0;
  rep(i, 0, n) {
    int x, y;
    cin >> x >> y;
    if (x == 0 && y == 0) {
      zc++;
      continue;
    }
    if (y < 0) {
      y *= -1;
      x *= -1;
    }
    int g = __gcd(abs(x), abs(y));
    x /= g;
    y /= g;
    m[{x, y}]++;
  }
  set<pii> s;

  mod_int ans = 1;

  for (auto k : m) {
    pii cur = k.fr;
    int occ = k.sc;
    pii perp = {-cur.sc, cur.fr};
    if (perp.sc < 0) {
      perp.fr *= -1;
      perp.sc *= -1;
    }
    if (s.count(perp)) {
      ans = ans + ans / mod_int(2).pow(m[perp]) * (mod_int(2).pow(k.sc) - 1);
    } else {
      ans *= mod_int(2).pow(k.sc);
    }

    s.insert(cur);
  }
  cout << (ans + zc - 1);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
#ifdef SEIVE
  seive();
#endif
#ifdef NCR
  init();
#endif
  int t = 1;
  // cin>>t;
  while (t--)
    solve();
  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define all(x) (x).begin(), (x).end()
#define uniq(v) (v).erase(unique(all(v)), (v).end())
#define sz(x) (int)((x).size())
#define fr first
#define sc second
#define pii pair<int, int>
#define rep(i, a, b) for (int i = a; i < b; i++)
#define mem1(a) memset(a, -1, sizeof(a))
#define mem0(a) memset(a, 0, sizeof(a))
#define ppc __builtin_popcount
#define ppcll __builtin_popcountll

template <typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &a) {
  in >> a.fr >> a.sc;
  return in;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &out, pair<T1, T2> a) {
  out << a.fr << " " << a.sc;
  return out;
}
template <typename T, typename T1> T amax(T &a, T1 b) {
  if (b > a)
    a = b;
  return a;
}
template <typename T, typename T1> T amin(T &a, T1 b) {
  if (b < a)
    a = b;
  return a;
}

const long long INF = 1e18;
const int32_t M = 1e9 + 7;
const int32_t MM = 998244353;

const int N = 2e5 + 5;

const int32_t MOD = M;
struct mod_int {
  int32_t val;
  mod_int(long long v = 0) {
    if (v < 0)
      v = v % MOD + MOD;
    if (v >= MOD)
      v %= MOD;
    val = v;
  }

  static int32_t mod_inv(int32_t a, int32_t m = MOD) {
    int32_t g = m, r = a, x = 0, y = 1;
    while (r != 0) {
      int32_t q = g / r;
      g %= r;
      swap(g, r);
      x -= q * y;
      swap(x, y);
    }
    return x < 0 ? x + m : x;
  }
  static unsigned fast_mod(uint64_t x, unsigned m = MOD) {
#if !defined(_WIN32) || defined(_WIN64)
    return x % m;
#endif
    unsigned x_high = x >> 32, x_low = (unsigned)x;
    unsigned quot, rem;
    asm("divl %4\\n" : "=a"(quot), "=d"(rem) : "d"(x_high), "a"(x_low), "r"(m));
    return rem;
  }

  explicit operator int() const { return val; }
  mod_int &operator+=(const mod_int &other) {
    val += other.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  mod_int &operator-=(const mod_int &other) {
    val -= other.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  mod_int &operator*=(const mod_int &other) {
    val = fast_mod((uint64_t)val * other.val);
    return *this;
  }
  mod_int &operator/=(const mod_int &other) { return *this *= other.inv(); }
  friend mod_int operator+(const mod_int &a, const mod_int &b) {
    return mod_int(a) += b;
  }
  friend mod_int operator-(const mod_int &a, const mod_int &b) {
    return mod_int(a) -= b;
  }
  friend mod_int operator*(const mod_int &a, const mod_int &b) {
    return mod_int(a) *= b;
  }
  friend mod_int operator/(const mod_int &a, const mod_int &b) {
    return mod_int(a) /= b;
  }
  mod_int &operator++() {
    val = val == MOD - 1 ? 0 : val + 1;
    return *this;
  }
  mod_int &operator--() {
    val = val == 0 ? MOD - 1 : val - 1;
    return *this;
  }
  mod_int operator++(int32_t) {
    mod_int before = *this;
    ++*this;
    return before;
  }
  mod_int operator--(int32_t) {
    mod_int before = *this;
    --*this;
    return before;
  }
  mod_int operator-() const { return val == 0 ? 0 : MOD - val; }
  bool operator==(const mod_int &other) const { return val == other.val; }
  bool operator!=(const mod_int &other) const { return val != other.val; }
  mod_int inv() const { return mod_inv(val); }
  friend ostream &operator<<(ostream &stream, const mod_int &m) {
    return stream << m.val;
  }
  friend istream &operator>>(istream &stream, mod_int &m) {
    return stream >> m.val;
  }

  mod_int pow(long long p) const {
    assert(p >= 0);
    mod_int a = *this, result = 1;
    while (p > 0) {
      if (p & 1)
        result *= a;

      a *= a;
      p >>= 1;
    }
    return result;
  }
};

map<pii, int> m;

void solve() {
  int n;
  cin >> n;
  rep(i, 0, n) {
    int x, y;
    cin >> x >> y;
    if (y < 0) {
      y *= -1;
      x *= -1;
    }
    int g = __gcd(abs(x), abs(y));
    x /= g;
    y /= g;
    m[{x, y}]++;
  }
  set<pii> s;

  mod_int ans = 1;

  for (auto k : m) {
    pii cur = k.fr;
    int occ = k.sc;
    pii perp = {-cur.sc, cur.fr};
    if (perp.sc < 0) {
      perp.fr *= -1;
      perp.sc *= -1;
    }
    if (s.count(perp)) {
      ans = ans + ans / mod_int(2).pow(m[perp]) * (mod_int(2).pow(k.sc) - 1);
    } else {
      ans *= mod_int(2).pow(k.sc);
    }

    s.insert(cur);
  }
  cout << ans - 1;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
#ifdef SEIVE
  seive();
#endif
#ifdef NCR
  init();
#endif
  int t = 1;
  // cin>>t;
  while (t--)
    solve();
  return 0;
}