Language: C++

#pragma GCC optimize("Ofast")
#pragma GCC target("avx2,tune=native")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("trapv")
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using pi = pair<ll, ll>;
const int mod = 1000000007;
const ll inf = 1e18;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using ld = double;
using vec = complex<ld>;
#define x real()
#define y imag()
ld dot(vec a, vec b) {
	return (conj(a)*b).x;
}
ld cross(vec a, vec b) {
	return (conj(a)*b).y;
}
istream& operator>>(istream& in, vec &v) {
	ld a, b;
	in >> a >> b;
	v = vec(a, b);
	return in;
}
bool cw(vector<pair<vec, int>> &hull, vec &v) {
	int n = hull.size();
	if(n < 2) return true;
	return cross(hull[n-1].first-hull[n-2].first, v-hull[n-1].first)<0;
}
ld ans[100100];
int main() { //DINIC ORZ
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n;
	cin >> n;
	vector<pair<vec, int>> v;
	v.resize(n);
	int _T = 0;
	for(auto &i : v) {
		cin >> i.first;
		i.second = ++_T;
	}
	for(auto &i : v) {
		if(i.first.x < v.back().first.x)
			swap(v.back(), i);
	}
	vector<pair<vec, int>> hull {v.back()};
	v.pop_back();
	sort(all(v), [&](const pair<vec, int> &a, const pair<vec, int> &b) {
		return cross(a.first-hull[0], b.first-hull[0]) < 0;
	});
	for(auto i : v) {
		while(!cw(hull, i.first)) hull.pop_back();
		hull.pb(i);
	}
	for(int i = 0; i < hull.size(); i++) {
		vec l = (i?hull[i-1]:hull.back()).first;
		vec r = (i+1<hull.size()?hull[i+1]:hull[0]).first;
//		cout << hull[i].first << " " << l << " " << r << "\n";
		l-=hull[i].first,	r-=hull[i].first;
		ld angle = M_PI - acos(((dot(l, r)/abs(l))/abs(r)));
//		cout << hull[i].first << " " << l << " " << r << "\n";
//		cout << dot(l, r) << "\n";
		ans[hull[i].second] = angle/(2*M_PI);
	}
	cout << fixed << setprecision(15);
	for(int i = 1; i <=n; i++) cout << ans[i] << "\n";
}



Compiler output:
a.cc: In lambda function:
a.cc:61:37: error: no match for 'operator-' (operand types are 'const std::complex<double>' and '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'})
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:5:
/usr/include/c++/14/bits/stl_iterator.h:618:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__y.base() - __x.base())) std::operator-(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  618 |     operator-(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:618:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::reverse_iterator<_Iterator>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__x.base() - __y.base())) std::operator-(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1790 |     operator-(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::move_iterator<_IteratorL>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/complex:370:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const complex<_Tp>&)'
  370 |     operator-(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:370:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'} is not derived from 'const std::complex<_Tp>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/complex:379:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const _Tp&)'
  379 |     operator-(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:379:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   deduced conflicting types for parameter 'const _Tp' ('double' and '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'})
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/complex:388:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const _Tp&, const complex<_Tp>&)'
  388 |     operator-(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:388:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'} is not derived from 'const std::complex<_Tp>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/complex:465:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&)'
  465 |     operator-(const complex<_Tp>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:465:5: note:   candidate expects 1 argument, 2 provided
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<std::complex<double>, int> >, std::pair<std::complex<double>, int> >::value_type' {aka 'std::pair<std::complex<double>, int>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const valarray<_Tp>&, const valarray<_Tp>&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:61:44: note:   'const std::complex<double>' is not derived from 'const std::valarray<_Tp>'
   61 |                 return cross(a.first-hull[0], b.first-hull[0]) < 0;
      |                                            ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction