Language: C++

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <forward_list>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#if __has_include(<optional>)
#include <optional>
#elif __has_include(<experimental/optional>)
#include <experimental/optional>
#endif
#include <queue>
#include <random>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#if __has_include(<variant>)
#include <variant>
#elif __has_include(<experimental/variant>)
#include <experimental/variant>
#endif
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <vector>
// using namespace std;
constexpr int64_t MOD = 1000000007;

template <class T>
class read;

template <class T, size_t n>
class read<std::array<T, n>>
{
public:
	using ret_type = std::array<T, n>;
	ret_type operator()() const
	{
		ret_type v;
		for (size_t i = 0; i < n; i++) v[i] = read<T>()();
		return v;
	}
};

template <class T>
constexpr std::size_t _tuple_size_v = std::tuple_size<T>::value;
template <class F, class Tuple, std::size_t... I>
constexpr decltype(auto) _apply_impl(F&& f, Tuple&& t, std::index_sequence<I...>)
{
	return std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...);
}
template <class F, class Tuple>
constexpr decltype(auto) _apply(F&& f, Tuple&& t)
{
	return _apply_impl(std::forward<F>(f), std::forward<Tuple>(t),
	                   std::make_index_sequence<_tuple_size_v<std::remove_reference_t<Tuple>>>{});
}

template <class... Ts>
class read<std::tuple<Ts...>>
{
public:
	using ret_type = std::tuple<Ts...>;
	ret_type operator()() const
	{
		ret_type v;
		::_apply([](auto&... args) { (void)std::initializer_list<int>{(void(f(args)), 0)...}; }, v);
		return v;
	}

private:
	template <class T>
	static int f(T& arg)
	{
		arg = read<T>()();
		return 0;
	}
};

template <class T1, class T2>
class read<std::pair<T1, T2>>
{
public:
	using ret_type = std::pair<T1, T2>;
	ret_type operator()() const { return ret_type{read<T1>()(), read<T2>()()}; }
};

template <class T, class Allocator>
class read<std::vector<T, Allocator>>
{
public:
	using ret_type = std::vector<T, Allocator>;
	ret_type operator()(size_t len) const
	{
		ret_type v;
		for (size_t i = 0; i < len; i++) v.push_back(read<T>()());
		return v;
	}
};

template <class T>
class read
{
public:
	using ret_type = T;
	ret_type operator()() const
	{
		ret_type v;
		std::cin >> v;
		return v;
	}
};

template <class T, size_t n>
std::ostream& operator<<(std::ostream& os, const std::array<T, n>& v)
{
	auto f = false;
#ifdef MY_RICH_PRINT
	os << "array(";
#endif
	for (auto& e : v)
	{
		if (f)
#ifdef MY_RICH_PRINT
			os << ", ";
#else
			os << " ";
#endif
		os << e;
		f = true;
	}
#ifdef MY_RICH_PRINT
	os << ")";
#endif
	return os;
}

template <class T>
static int my_cout_impl(const T& arg, std::ostream& os, bool& f)
{
	if (f)
#ifdef MY_RICH_PRINT
		os << ", ";
#else
		os << " ";
#endif
	os << arg;
	f = true;
	return 0;
}

template <class... Ts>
std::ostream& operator<<(std::ostream& os, const std::tuple<Ts...>& v)
{
	auto f = false;
#ifdef MY_RICH_PRINT
	os << "tuple(";
#endif
	::_apply([&os, &f](const auto&... args) { (void)std::initializer_list<int>{(void(my_cout_impl(args, os, f)), 0)...}; }, v);
#ifdef MY_RICH_PRINT
	os << ")";
#endif
	return os;
}

template <class T1, class T2>
std::ostream& operator<<(std::ostream& os, const std::pair<T1, T2>& v)
{
#ifdef MY_RICH_PRINT
	return os << "pair(" << v.first << ", " << v.second << ")";
#else
	return os << v.first << " " << v.second;
#endif
}

template <class T, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::vector<T, Allocator>& v)
{
	auto f = false;
#ifdef MY_RICH_PRINT
	os << "vector(";
#endif
	for (auto& e : v)
	{
		if (f)
#ifdef MY_RICH_PRINT
			os << ", ";
#else
			os << " ";
#endif
		os << e;
		f = true;
	}
#ifdef MY_RICH_PRINT
	os << ")";
#endif
	return os;
}

template <class Key, class T, class Compare, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::map<Key, T, Compare, Allocator>& v)
{
#ifndef MY_RICH_PRINT
	assert(0);
#endif
	auto f = false;
	os << "map(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p.first << ": " << p.second;
		f = true;
	}
	return os << ")";
}

template <class Key, class T, class Compare, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::multimap<Key, T, Compare, Allocator>& v)
{
#ifndef MY_RICH_PRINT
	assert(0);
#endif
	auto f = false;
	os << "multimap(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p.first << ": " << p.second;
		f = true;
	}
	return os << ")";
}

template <class Key, class Compare, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::set<Key, Compare, Allocator>& v)
{
	auto f = false;
#ifdef MY_RICH_PRINT
	os << "set(";
#endif
	for (auto& p : v)
	{
		if (f)
#ifdef MY_RICH_PRINT
			os << ", ";
#else
			os << " ";
#endif
		os << p;
		f = true;
	}
#ifdef MY_RICH_PRINT
	os << ")";
#endif
	return os;
}

template <class Key, class Compare, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::multiset<Key, Compare, Allocator>& v)
{
	auto f = false;
	os << "multiset(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p;
		f = true;
	}
	return os << ")";
}

template <class Key, class T, class Hash, class Pred, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::unordered_map<Key, T, Hash, Pred, Allocator>& v)
{
#ifndef MY_RICH_PRINT
	assert(0);
#endif
	auto f = false;
	os << "unordered_map(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p.first << ": " << p.second;
		f = true;
	}
	return os << ")";
}

template <class Key, class T, class Hash, class Pred, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::unordered_multimap<Key, T, Hash, Pred, Allocator>& v)
{
#ifndef MY_RICH_PRINT
	assert(0);
#endif
	auto f = false;
	os << "unordered_multimap(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p.first << ": " << p.second;
		f = true;
	}
	return os << ")";
}

template <class Key, class Hash, class Pred, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::unordered_set<Key, Hash, Pred, Allocator>& v)
{
	auto f = false;
	os << "unordered_set(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p;
		f = true;
	}
	return os << ")";
}

template <class Key, class Hash, class Pred, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::unordered_multiset<Key, Hash, Pred, Allocator>& v)
{
	auto f = false;
	os << "unordered_multiset(";
	for (auto& p : v)
	{
		if (f) os << ", ";
		os << p;
		f = true;
	}
	return os << ")";
}

template <class T, class Container>
std::ostream& operator<<(std::ostream& os, const std::queue<T, Container>& v)
{
	std::queue<T, Container> v2 = v;
	auto f = false;
	os << "queue(";
	while (!v2.empty())
	{
		os << (f ? ", " : "front: ") << v2.front();
		v2.pop();
		f = true;
	}
	return os << ")";
}

template <class T, class Container>
std::ostream& operator<<(std::ostream& os, const std::stack<T, Container>& v)
{
	std::stack<T, Container> v2 = v;
	auto f = false;
	os << "stack(";
	while (!v2.empty())
	{
		os << (f ? ", " : "top: ") << v2.top();
		v2.pop();
		f = true;
	}
	return os << ")";
}

template <class T, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::deque<T, Allocator>& v)
{
	auto f = false;
	os << "deque(";
	for (auto& e : v)
	{
		if (f) os << ", ";
		os << e;
		f = true;
	}
	return os << ")";
}

template <class T, class Container, class Compare>
std::ostream& operator<<(std::ostream& os, const std::priority_queue<T, Container, Compare>& v)
{
	std::priority_queue<T, Container, Compare> v2 = v;
	auto f = false;
	os << "priority_queue(";
	while (!v2.empty())
	{
		os << (f ? ", " : "top: ") << v2.top();
		v2.pop();
		f = true;
	}
	return os << ")";
}

template <class T, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::list<T, Allocator>& v)
{
	auto f = false;
	os << "list(";
	for (auto& e : v)
	{
		if (f) os << ", ";
		os << e;
		f = true;
	}
	return os << ")";
}

template <class T>
std::ostream& operator<<(std::ostream& os, const std::initializer_list<T>& v)
{
	auto f = false;
	os << "initializer_list(";
	for (auto& e : v)
	{
		if (f) os << ", ";
		os << e;
		f = true;
	}
	return os << ")";
}

template <class T, class Allocator>
std::ostream& operator<<(std::ostream& os, const std::forward_list<T, Allocator>& v)
{
	auto f = false;
	os << "forward_list(";
	for (auto& e : v)
	{
		if (f) os << ", ";
		os << e;
		f = true;
	}
	return os << ")";
}

// 座圧
template <class T, class Int = int>
std::map<T, Int> compress(const std::vector<T>& v)
{
	std::map<T, Int> m;
	for (auto x : v) m[x] = 0;
	Int n = 0;
	for (auto& t : m) t.second = n++;
	return m;
}

// [b, ..., e] must be a shuffle of [0, 1, ..., len - 1] (len = e - b)
template <class RanIt>
std::vector<std::vector<typename std::iterator_traits<RanIt>::value_type>> to_cycles(RanIt b, RanIt e)
{
	using T = typename std::iterator_traits<RanIt>::value_type;
	std::vector<std::vector<T>> cycs;
	T len = e - b;
	std::vector<bool> done(len, false);
	for (T i = 0; i < len; ++i)
	{
		if (done[i]) continue;
		std::vector<T> cyc;
		cyc.push_back(i);
		auto j = b[i];
		while (j != i)
		{
			cyc.push_back(j);
			done[j] = true;
			j = b[j];
		}
		cycs.push_back(std::move(cyc));
	}
	return cycs;
}

template <class T>
auto to_cycles(const T& v)
{
	return to_cycles(std::begin(v), std::end(v));
}

template <class T, size_t n>
double norm(const std::array<T, n>& p)
{
	auto s = 0.0;
	for (int i = 0; i < n; ++i) s += double(p[i]) * p[i];
	return std::sqrt(s);
}
template <class T, size_t n>
double dist(const std::array<T, n>& p, const std::array<T, n>& q)
{
	std::array<T, n> d;
	for (int i = 0; i < n; ++i) d[i] = p[i] - q[i];
	return norm(d);
}

template <class Int>
Int gcd(Int n, Int m)
{
	while (m > 0)
	{
		Int t = n % m;
		n = m;
		m = t;
	}
	return n;
}

template <class Int>
std::array<Int, 2> solve_linear(Int n, Int m)
{
	// static_assert(std::is_integral_v<Int> && std::is_signed_v<Int>);
	auto A = std::array<std::array<Int, 2>, 2>{std::array<Int, 2>{n < 0 ? -1 : 1, 0}, std::array<Int, 2>{0, m < 0 ? -1 : 1}};
	if (n < 0) n *= -1;
	if (m < 0) m *= -1;
	while (m > 0)
	{
		Int q = n / m, r = n % m;
		n = m;
		m = r;
		for (int i = 0; i < 2; ++i)
		{
			Int x = A[i][1];
			A[i][1] = A[i][0] - q * x;
			A[i][0] = x;
		}
	}
	return std::array<Int, 2>{A[0][0], A[1][0]};
}

template <class Int>
Int mod(Int a, Int mod)
{
	// static_assert(std::is_integral_v<Int>);
	return (a % mod + mod) % mod;
}

template <class Int>
Int inverse(Int a, Int M)
{
	return mod(solve_linear(mod(a, M), M)[0], M);
}

template <class Int>
Int pow(Int a, Int p, Int mod)
{
	// static_assert(std::is_integral_v<Int>);
	Int y = 1;
	Int x = a;
	while (p > 0)
	{
		if ((p & 1) == 1) y = (y * x) % mod;
		p >>= 1;
		x = (x * x) % mod;
	}
	return y;
}

template <class Int, class Pred>
Int first_binary(Int min, Int max, Pred pred)
{
	// static_assert(std::is_integral_v<Int>);
	while (min < max)
	{
		Int mid = min + (max - min) / 2;
		if (pred(mid))
			max = mid;
		else
			min = mid + 1;
	}
	return min;
}

template <class Int>
std::vector<Int> get_fact(int max, Int mod)
{
	std::vector<Int> x{1};
	for (Int i = 1; i <= max; ++i) x.push_back(i * x.back() % mod);
	return x;
}

template <class Int>
std::vector<Int> get_fact_inv(int max, Int mod)
{
	Int fc = 1;
	for (Int i = 2; i <= max; i++) fc = fc * i % mod;
	std::vector<Int> x(max + 1);
	x[max] = inverse(fc, mod);
	for (Int i = max; i >= 1; --i) x[i - 1] = x[i] * i % mod;
	return x;
}

class union_find
{
	int n_;
	std::unique_ptr<int[]> par_, rk_, sz_;

public:
	union_find(int cap) : n_(cap), par_(std::make_unique<int[]>(cap)), rk_(std::make_unique<int[]>(cap)), sz_(std::make_unique<int[]>(cap))
	{
		for (int i = 0; i < n_; ++i)
		{
			par_[i] = i;
			rk_[i] = 0;
			sz_[i] = 1;
		}
	}
	int size(int v) { return sz_[root(v)]; }
	int root(int v) { return par_[v] == v ? v : par_[v] = root(par_[v]); }
	bool unite(int u, int v)
	{
		if ((u = root(u)) == (v == root(v))) return false;
		if (rk_[u] < rk_[v])
		{
			par_[u] = v;
			sz_[v] += sz_[u];
		}
		else
		{
			par_[v] = u;
			sz_[u] += sz_[v];
			if (rk_[u] == rk_[v]) ++rk_[u];
		}
		return true;
	}
	bool has_united(int u, int v) { return root(u) == root(v); }
};

template <class T>
bool ch_min(T& x, const T& y)
{
	if (x > y)
	{
		x = y;
		return true;
	}
	return false;
}
template <class T>
bool ch_max(T& x, const T& y)
{
	if (x < y)
	{
		x = y;
		return true;
	}
	return false;
}

template <class Int = int>
std::vector<Int> get_primes(Int n)
{
	if (n < 3) n = 3;
	Int m = (n - 1) >> 1;
	std::vector<Int> ps{2};
	ps.reserve(n / std::log(n));
	std::vector<bool> ok(m, true);
	for (Int i = 0; i < m; ++i)
		if (ok[i])
		{
			Int p = 2 * i + 3;
			ps.push_back(p);
			for (Int k = 3 * i + 3; k < m; k += p) ok[k] = false;
		}
	return ps;
}

bool is_prime(uint64_t n)
{
	if (n <= 1 || (n > 2 && n % 2 == 0)) return false;
	// constexpr auto test = std::array{2, 3, 5, 7, 11, 13, 17, 19, 23, 111};
	auto d = n - 1;
	int s = 0;
	while (d % 2 == 0)
	{
		++s;
		d /= 2;
	}
	auto f = [n, d, s](uint64_t t) {
		auto x = pow(t, d, n);
		if (x == 1) return true;
		for (int r = 0; r < s; ++r)
		{
			if (x == n - 1) return true;
			x = (x * x) % n;
		}
		return false;
	};
	for (auto i : {2, 3, 5, 7, 11, 13, 17, 19, 23})
	{
		if (i >= n) return true;
		if (!f(i)) return false;
	}
	// for (int i = 0; test[i] < n && test[i] != 111; ++i)
	//	if (!f(test[i])) return false;
	return true;
}

namespace mp = boost::multiprecision;
using real = mp::number<mp::cpp_dec_float<1000>>;

using point = std::array<real, 2>;
point operator-(const point& a, const point& b) { return {a[0] - b[0], a[1] - b[1]}; }
point operator+(const point& a, const point& b) { return {a[0] + b[0], a[1] + b[1]}; }
point operator*(const real& r, const point& a) { return {a[0] * r, a[1] * r}; }
point operator/(const point& a, const real& r) { return {a[0] / r, a[1] / r}; }
real length2(const point& a) { return a[0] * a[0] + a[1] * a[1]; }
real length(const point& a) { return mp::sqrt(length2(a)); }

struct circle
{
	point c;
	real r;
	circle(const point& c, const real& r) : c(c), r(r) {}
	bool contains(const point& a) const { return length2(a - c) <= r * r + real("1e-100"); }
	friend circle operator+(const circle& c, const point& p) { return {c.c + p, c.r}; }
};

// 0, a, b
circle circum_circle3(const point& a, const point& b)
{
	auto det = b[0] * a[1] - b[1] * a[0];
	if (mp::abs(det) < real("1e-100")) return {a, 0};
	point c{a[1] * length2(b) - b[1] * length2(a), b[0] * length(a) - a[0] * length(b)};
	c = c / (2 * det);
	return {c, length(c)};
}
circle circum_circle3(const point& a, const point& b, const point& c) { return circum_circle3(a - c, b - c) + c; }
circle circum_circle2(const point& a, const point& b) { return {(a + b) / 2, length(b - a) / 2}; }

void solve()
{
	auto N = read<int>()();
	auto ps = read<std::vector<point>>()(N);
	auto check = [&ps, N](const circle& c) {
		for (int i = 0; i < N; i++)
			if (!c.contains(ps[i])) return false;
		return true;
	};
	circle min{{0, 0}, real("1e300")};
	for (int i = 0; i < N; i++)
		for (int j = i + 1; j < N; j++)
		{
			auto c = circum_circle2(ps[i], ps[j]);
			if (c.r < min.r && check(c)) min = c;
		}
	for (int i = 0; i < N; i++)
		for (int j = i + 1; j < N; j++)
			for (int k = j + 1; k < N; k++)
			{
				auto c = circum_circle3(ps[i], ps[j], ps[k]);
				if (c.r < min.r && check(c)) min = c;
			}
	std::cout << std::setprecision(20) << std::scientific << min.r << std::endl;
}

int main()
{
	using std::cout;
	using std::endl;
	using std::string;
	using std::vector;
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	solve();
	cout << std::flush;
	return 0;
}


Compiler output:
a.cc:46:10: fatal error: boost/multiprecision/cpp_dec_float.hpp: No such file or directory
   46 | #include <boost/multiprecision/cpp_dec_float.hpp>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.