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

#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("O3")
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPP(i, n) for (int i = 1; i <= n; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define EPS (1e-9)
#define INF (1e17)
#define PI (acos(-1))
// const double PI = acos(-1);
// const double EPS = 1e-15;
// long long INF=(long long)1E17;
#define i_7 (long long)(1e9 + 7)
// #define i_7 998'244'353
long mod(long a) {
  long long c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
long long po(long a, long b) {
  if (b == 0) {
    return 1;
  }

  long long z = po(a, b / 2);
  z = mod(z * z);
  if (b % 2 != 0) {
    z = mod(a * z);
  }
  return z;
}

bool prime_(int n) {
  if (n == 1) {
    return false;
  } else if (n == 2) {
    return true;
  } else {
    for (int i = 2; i <= std::sqrt(n); i++) {
      if (n % i == 0) {
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b) {
  if (a < b) {
    std::swap(a, b);
  }
  if (a % b == 0) {
    return b;
  } else {
    return gcd_(b, a % b);
  }
}

long long lcm_(long long x, long long y) { return (x / gcd_(x, y)) * y; }

// using namespace std;
// using namespace boost::multiprecision;
// using namespace __gnu_pbds;

int main() {
  using namespace std;
  long long n;
  cin >> n;
  long long a[n], b[n];
  REP(i, n) cin >> a[i] >> b[i];
  typedef pair<long long, long long> P;
  map<P, long long> cnt;
  for (long long i = 0; i < n; i++) {
    if (a[i] == 0LL && b[i] == 0LL) {
      cnt[P(a[i], b[i])]++;
      continue;
    }
    if (a[i] == 0LL) {
      cnt[P(0LL, 1LL)]++;
      continue;
    }
    if (b[i] == 0) {
      cnt[P(1LL, 0LL)]++;
      continue;
    }
    long long g = gcd_(abs(a[i]), abs(b[i]));
    a[i] /= g;
    b[i] /= g;
    if (a[i] < 0) {
      a[i] = 0LL - a[i];
      b[i] = 0LL - b[i];
    }
    cnt[P(a[i], b[i])]++;
  }

  long long ans = 1;
  long long extra = cnt[P(0, 0)];
  // long long c = 0;
  for (auto p : cnt) {
    if (p.second < 0)
      continue;
    if (p.first.first == 0LL && p.first.second == 0)
      continue;
    long long coA = p.first.second;
    long long coB = -p.first.first;
    if (coA < 0) {
      coA = 0LL - coA;
      coB = 0LL - coB;
    }
    long long coeff = mod(po(2LL, p.second) + po(2LL, cnt[P(coA, coB)]) - 1);
    cnt[P(coA, coB)] = -1;
    ans *= coeff;
    ans = mod(ans);
  }

  ans -= 1;
  ans = mod(ans);
  ans += extra;
  ans = mod(ans);
  cout << ans << endl;
  return 0;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("O3")
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPP(i, n) for (int i = 1; i <= n; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define EPS (1e-9)
#define INF (1e17)
#define PI (acos(-1))
// const double PI = acos(-1);
// const double EPS = 1e-15;
// long long INF=(long long)1E17;
#define i_7 (long long)(1e9 + 7)
// #define i_7 998'244'353
long mod(long a) {
  long long c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
long long po(long a, long b) {
  if (b == 0) {
    return 1;
  }

  long long z = po(a, b / 2);
  z = mod(z * z);
  if (b % 2 != 0) {
    z = mod(a * z);
  }
  return z;
}

bool prime_(int n) {
  if (n == 1) {
    return false;
  } else if (n == 2) {
    return true;
  } else {
    for (int i = 2; i <= std::sqrt(n); i++) {
      if (n % i == 0) {
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b) {
  if (a < b) {
    std::swap(a, b);
  }
  if (a % b == 0) {
    return b;
  } else {
    return gcd_(b, a % b);
  }
}

long long lcm_(long long x, long long y) { return (x / gcd_(x, y)) * y; }

// using namespace std;
// using namespace boost::multiprecision;
// using namespace __gnu_pbds;

int main() {
  using namespace std;
  long long n;
  cin >> n;
  long long a[n], b[n];
  REP(i, n) cin >> a[i] >> b[i];
  typedef pair<long long, long long> P;
  map<P, long long> cnt;
  for (long long i = 0; i < n; i++) {
    long long g = gcd_(abs(a[i]), abs(b[i]));
    a[i] /= g;
    b[i] /= g;
    if (a[i] < 0) {
      a[i] = 0LL - a[i];
      b[i] = 0LL - b[i];
    }
    cnt[P(a[i], b[i])]++;
  }

  long long ans = 1;
  // long long c = 0;
  for (auto p : cnt) {
    if (p.second < 0)
      continue;
    long long coA = p.first.second;
    long long coB = -p.first.first;
    if (coA < 0) {
      coA = 0LL - coA;
      coB = 0LL - coB;
    }
    long long coeff = mod(po(2LL, p.second) + po(2LL, cnt[P(coA, coB)]) - 1);
    cnt[P(coA, coB)] = -1;
    ans *= coeff;
    ans = mod(ans);
  }

  ans -= 1;
  ans = mod(ans);
  cout << ans << endl;
  return 0;
}