Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<pair<ll,pair<ll,ll>>> ii;
#define pb push_back
#define ff first
#define ss second
//For geometric calculations, try to use these kind of constructs


// Creating a structure point, having coordinates and distance
struct Point {
    double x, y;
    // a function that does not modify the struct
	double distance(const Point& that) const;
};


//returns the distance of given point from another
double Point::distance(const Point& that) const {
	return ((*this) - that).length();
}


// for finding Angle 
struct Angle {
	double sin, cos;
	Angle operator-()const {
		return Angle{ -sin, cos };
	}
};


// Creating struct Vector
struct Vector {
	double dx, dy;
	Vector rotate(const Angle angle) const {
		return Vector{ dx * angle.cos - dy * angle.sin, dy * angle.cos + dx * angle.sin };
	}
	double length() const {
		return  sqrt(dx * dx + dy * dy);
	}
	Vector change_length(const double new_length) const {
		const auto current = length();
		return Vector{ dx / current * new_length, dy / current * new_length };
	}
};
 

// operator - for Vector 
Vector operator-(const Point a, const Point b) {
	return Vector{ a.x - b.x, a.y - b.y };
}


// operator + for Vector
Point operator+(const Point a, const Vector v)
{
	return Point{ a.x + v.dx, a.y + v.dy };
}


//
struct Circle {
	Point center;
	double radius;
 
};


//
Angle angle_of(double opposite, double a, double b) {
	double cos = (a * a + b * b - opposite * opposite) / (2 * a * b);
	return Angle{  sqrt(1 - cos * cos), cos };
}
 

//
bool has_intersection(const Circle& a, const Circle& b) {
	return a.center.distance(b.center) <= a.radius + b.radius;
}


//
bool is_contains(const Circle& outer, const Circle& inner) {
	if (outer.radius < inner.radius) return false;
	return outer.center.distance(inner.center) + inner.radius <= outer.radius;
}


//
vector<Point> cross_point(const Circle a, const Circle b) {
	if (!has_intersection) return {};
	if (is_contains(a, b)) return { b.center };
 	if (is_contains(b, a)) return { a.center };
	const auto angle = angle_of(b.radius, a.radius, a.center.distance(b.center));
	const auto vec = (b.center - a.center).change_length(a.radius);
	return { a.center + vec.rotate(angle), a.center + vec.rotate(-angle) };
}


//
int count_circle(const Point target, const  vector<Circle>& circles) {
	int count = 0;
	for (const auto c : circles) {
		if (c.center.distance(target) <= c.radius + 1e-6) {
			++count;
		}
	}
	return count;
}


//
vector<Point> cross_points(const  vector<Circle>& circles) {
	 vector<Point> points;
	for (auto i = 0; i < circles.size(); ++i) {
		for (auto j = 0; j < circles.size(); ++j) {
			for (const auto cp : cross_point(circles[i], circles[j])) {
				points.push_back(cp);
			}
		}
	}
	return points;
}


//
struct Meet {
	Point position;
	double headness;
};


//
vector<Circle> to_circles(double time, const  vector<Meet>& meets) {
	 vector<Circle> result; result.reserve(meets.size());
	for (const auto& m : meets) {
		result.push_back(Circle{ m.position, time / m.headness});
	}
	return result;
}


//
bool can_make(int count, double time, const  vector<Meet>& meat) {
	const auto circles = to_circles(time, meat);
	for (const auto cp : cross_points(circles)) {
		if (count_circle(cp, circles) >= count) return true;
	}
	return false;
}


int main() {
	int n, k;
    cin >> n >> k;
	vector<Meet> meets(n);
	for (auto& m : meets) 
        cin >> m.position.x >> m.position.y >> m.headness;  // m.headness == cost
	double min = 0, max = 1000000;
	for (int i = 0; i < 100; ++i) {
		const auto mid = (min + max) / 2;
		if (can_make(k, mid, meets)) {
			max = mid;
		}
		else {
			min = mid;
		}
	}
	cout << setprecision(7) << fixed << max << endl;
}


Compiler output:
a.cc: In member function 'double Point::distance(const Point&) const':
a.cc:21:25: error: no match for 'operator-' (operand types are 'const Point' and 'const Point')
   21 |         return ((*this) - that).length();
      |                 ~~~~~~~ ^ ~~~~
      |                  |        |
      |                  |        const Point
      |                  const Point
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:1:
/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:21:27: note:   'const Point' is not derived from 'const std::reverse_iterator<_Iterator>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::move_iterator<_IteratorL>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
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:21:27: note:   'const Point' is not derived from 'const std::complex<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::complex<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::complex<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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:21:27: note:   'const Point' is not derived from 'const std::valarray<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/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/substitution failed:
a.cc:21:27: note:   'const Point' is not derived from 'const std::valarray<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:21:27: note:   'const Point' is not derived from 'const std::valarray<_Tp>'
   21 |         return ((*this) - that).length();
      |                           ^~~~