Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
#define MAX 200000
#define MOD 1000000007

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

long long combination2(long long n) {
	return n * (n - 1) / 2;
}

std::vector<std::vector<long long>> comb(int n, int r) {
	std::vector<std::vector<long long>> v(n + 1,
			std::vector<long long>(n + 1, 0));
	for (int i = 0; i < v.size(); i++) {
		v[i][0] = 1;
		v[i][i] = 1;
	}
	for (int j = 1; j < v.size(); j++) {
		for (int k = 1; k < j; k++) {
			v[j][k] = (v[j - 1][k - 1] + v[j - 1][k]);
		}
	}
	return v;
}

class IrreducibleFraction {
public:
	long long numerator, denomenator;
	IrreducibleFraction(long long n, long long d) {
		long long g = gcd(n, d);
		numerator = n / g;
		denomenator = d / g;
	}
	double value() {
		return (double) numerator / denomenator;
	}
	bool operator <(const IrreducibleFraction &i) const {
		return value() < i.value();
	}
	bool operator ==(const IrreducibleFraction &i) const {
		return ((value() * i.value() < 0)
				&& abs(numerator) == abs(i.denomenator)
				&& abs(denomenator) == abs(i.numerator));
	}
	IrreducibleFraction getInverse() {
		return IrreducibleFraction(denomenator, numerator);
	}

};

multiset<IrreducibleFraction> PosQ;
multiset<IrreducibleFraction> NegQ;
vector<pair<ll, ll>> Pair00;
vector<pair<ll, ll>> PairN0;
vector<pair<ll, ll>> Pair0N;

int main() {
	int N;
	cin >> N;
	for (int i = 0; i < N; i++) {
		ll A, B;
		if (A == 0 && B == 0) {
			Pair00.push_back(make_pair(A, B));
		} else if (A == 0) {
			Pair0N.push_back(make_pair(A, B));
		} else if (B == 0) {
			PairN0.push_back(make_pair(A, B));
		} else if ((A > 0 && B > 0) || (A < 0 && B < 0)) {
			PosQ.insert(IrreducibleFraction(A, B));
		} else {
			NegQ.insert(IrreducibleFraction(A, B));
		}
	}

	long cntNGPair = 0;
	for (multiset<IrreducibleFraction>::iterator it = PosQ.begin();
			it != PosQ.end(); it++) {
		IrreducibleFraction fra = *it;
		cntNGPair += NegQ.count(fra.getInverse());
	}

	cntNGPair += combination2(Pair00.size());
	cntNGPair += Pair00.size() * (N - Pair00.size());
	cntNGPair += Pair0N.size() * PairN0.size();

	long long allComb = -cntNGPair;
	for (int i = 1; i <= N; i++) {
		vector<vector<long long>> v = comb(N, i);
		allComb += v[N][i];
		allComb %= MOD;
	}

	cout << allComb << endl;

	return 0;
}


Compiler output:
a.cc: In member function 'bool IrreducibleFraction::operator<(const IrreducibleFraction&) const':
a.cc:50:29: error: passing 'const IrreducibleFraction' as 'this' argument discards qualifiers [-fpermissive]
   50 |                 return value() < i.value();
      |                        ~~~~~^~
a.cc:46:16: note:   in call to 'double IrreducibleFraction::value()'
   46 |         double value() {
      |                ^~~~~
a.cc:50:41: error: passing 'const IrreducibleFraction' as 'this' argument discards qualifiers [-fpermissive]
   50 |                 return value() < i.value();
      |                                  ~~~~~~~^~
a.cc:46:16: note:   in call to 'double IrreducibleFraction::value()'
   46 |         double value() {
      |                ^~~~~
a.cc: In member function 'bool IrreducibleFraction::operator==(const IrreducibleFraction&) const':
a.cc:53:31: error: passing 'const IrreducibleFraction' as 'this' argument discards qualifiers [-fpermissive]
   53 |                 return ((value() * i.value() < 0)
      |                          ~~~~~^~
a.cc:46:16: note:   in call to 'double IrreducibleFraction::value()'
   46 |         double value() {
      |                ^~~~~
a.cc:53:43: error: passing 'const IrreducibleFraction' as 'this' argument discards qualifiers [-fpermissive]
   53 |                 return ((value() * i.value() < 0)
      |                                    ~~~~~~~^~
a.cc:46:16: note:   in call to 'double IrreducibleFraction::value()'
   46 |         double value() {
      |                ^~~~~