Language: C++

#include <iostream>
#include <fstream>
#include <stdio.h>
#include <vector>
#include <string>
#include <math.h>
#include <algorithm>
#include <map>
#include <set>

#define sz(x) ((int)x.size())
#define all(x) (x).begin(), (x).end()
#define pb(x) push_back(x)
#define mp(x, y) make_pair(x, y)

typedef long long int64;

typedef lld lld;

using namespace std;

lld _abs(lld x) {
    if (x < 0) return -x;
	return x;
}

lld sqr(lld x) {
   return x * x;
}

lld det(const vector<vector<lld>> a) {
	
	return a[0][0] * (a[1][1] * a[2][2] - a[1][2] * a[2][1]) -
	       a[1][0] * (a[0][1] * a[2][2] - a[2][1] * a[0][2]) +
		   a[2][0] * (a[0][1] * a[1][2] - a[0][2] * a[1][1]);
}

pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
	lld len1 = sqr(x1) + sqr(y1);
	lld len2 = sqr(x2) + sqr(y2);
	lld len3 = sqr(x3) + sqr(y3);	
	vector<vector<lld>> a = { {len1, y1, 1} ,  {len2, y2, 1}, {len3, y3, 1} };
	vector<vector<lld>> b = { {x1, len1, 1} ,  {x2, len2, 1}, {x3, len3, 1} };
	vector<vector<lld>> c = { {x1, y1, 1} ,  {x2, y2, 1}, {x3, y3, 1} };
	lld sx = 0.5 * det(a);
    lld sy = 0.5 * det(b);
	lld A = det(c);
	if (_abs(A) < 1e-9) return {0, 0};
	sx /= A;
	sy /= A;
	return {sx, sy};
	
	
}	

int main() {
	ios_base::sync_with_stdio(0);

    int n;
	cin >> n;
	vector<lld> x(n);
    vector<lld> y(n);
	
	for (int i = 0; i < n; ++i) {
	    cin >> x[i] >> y[i];
	}
	
	lld ans = -1;
	for (int i = 0; i < n; ++i) {
	    for (int j = i + 1; j < n;  ++j) {
		    lld xr = (x[i] + x[j]) / 2;
			lld yr = (y[i] + y[j]) / 2;
			lld res = 0;
			for (int l = 0; l < n; ++l) {
			    res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
			}
			if (ans < 0 || ans >= res) {
			    ans = res;
			}
			
			
			for (int k = j + 1; k < n; ++k) {
				auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
				lld xr = p.first;
				lld yr = p.second;
				lld res = 0;
			
				for (int l = 0; l < n; ++l) {
					res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
				}
				if (ans < 0 || ans >= res) {
					ans = res;
				}
				
				
			}
			
		}
	}

    cout.precision(15);
	cout << sqrt(ans) << endl;

    return 0;
}


Compiler output:
a.cc:18:9: error: 'lld' does not name a type
   18 | typedef lld lld;
      |         ^~~
a.cc:22:1: error: 'lld' does not name a type
   22 | lld _abs(lld x) {
      | ^~~
a.cc:27:1: error: 'lld' does not name a type
   27 | lld sqr(lld x) {
      | ^~~
a.cc:31:1: error: 'lld' does not name a type
   31 | lld det(const vector<vector<lld>> a) {
      | ^~~
a.cc:38:6: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |      ^~~
a.cc:38:11: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |           ^~~
a.cc:38:14: error: template argument 1 is invalid
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |              ^
a.cc:38:14: error: template argument 2 is invalid
a.cc:38:21: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                     ^~~
a.cc:38:29: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                             ^~~
a.cc:38:37: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                                     ^~~
a.cc:38:45: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                                             ^~~
a.cc:38:53: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                                                     ^~~
a.cc:38:61: error: 'lld' was not declared in this scope
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                                                             ^~~
a.cc:38:67: error: expression list treated as compound expression in initializer [-fpermissive]
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                                                                   ^
a.cc: In function 'int main()':
a.cc:61:16: error: 'lld' was not declared in this scope
   61 |         vector<lld> x(n);
      |                ^~~
a.cc:61:19: error: template argument 1 is invalid
   61 |         vector<lld> x(n);
      |                   ^
a.cc:61:19: error: template argument 2 is invalid
a.cc:62:15: error: template argument 2 is invalid
   62 |     vector<lld> y(n);
      |               ^
a.cc:65:21: error: invalid types 'int[int]' for array subscript
   65 |             cin >> x[i] >> y[i];
      |                     ^
a.cc:65:29: error: invalid types 'int[int]' for array subscript
   65 |             cin >> x[i] >> y[i];
      |                             ^
a.cc:68:12: error: expected ';' before 'ans'
   68 |         lld ans = -1;
      |            ^~~~
      |            ;
a.cc:71:24: error: expected ';' before 'xr'
   71 |                     lld xr = (x[i] + x[j]) / 2;
      |                        ^~~
      |                        ;
a.cc:72:28: error: expected ';' before 'yr'
   72 |                         lld yr = (y[i] + y[j]) / 2;
      |                            ^~~
      |                            ;
a.cc:73:28: error: expected ';' before 'res'
   73 |                         lld res = 0;
      |                            ^~~~
      |                            ;
a.cc:75:29: error: 'res' was not declared in this scope
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                             ^~~
a.cc:75:48: error: 'xr' was not declared in this scope; did you mean 'x'?
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                ^~
      |                                                x
a.cc:75:54: error: invalid types 'int[int]' for array subscript
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                      ^
a.cc:75:44: error: 'sqr' was not declared in this scope; did you mean 'sqrt'?
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                            ^~~
      |                                            sqrt
a.cc:75:65: error: 'yr' was not declared in this scope; did you mean 'y'?
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                                 ^~
      |                                                                 y
a.cc:75:71: error: invalid types 'int[int]' for array subscript
   75 |                             res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                                       ^
a.cc:77:29: error: 'ans' was not declared in this scope; did you mean 'abs'?
   77 |                         if (ans < 0 || ans >= res) {
      |                             ^~~
      |                             abs
a.cc:77:47: error: 'res' was not declared in this scope
   77 |                         if (ans < 0 || ans >= res) {
      |                                               ^~~
a.cc:83:42: error: reference to 'find' is ambiguous
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                          ^~~~
In file included from /usr/include/c++/14/algorithm:86,
                 from a.cc:7:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:60:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> std::find(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
   60 | find(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:3842:5: note:                 'template<class _IIter, class _Tp> _IIter std::find(_IIter, _IIter, const _Tp&)'
 3842 |     find(_InputIterator __first, _InputIterator __last,
      |     ^~~~
In file included from /usr/include/c++/14/bits/locale_facets.h:48,
                 from /usr/include/c++/14/bits/basic_ios.h:37,
                 from /usr/include/c++/14/ios:46,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/streambuf_iterator.h:435:5: note:                 'template<class _CharT2> typename __gnu_cxx::__enable_if<std::__is_char<_CharT2>::__value, std::istreambuf_iterator<_CharT> >::__type std::find(istreambuf_iterator<_CharT>, istreambuf_iterator<_CharT>, const _CharT2&)'
  435 |     find(istreambuf_iterator<_CharT> __first,
      |     ^~~~
a.cc:38:16: note:                 'int find'
   38 | pair<lld, lld> find(lld x1, lld y1, lld x2, lld y2, lld x3, lld y3) {
      |                ^~~~
a.cc:83:48: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                ^
a.cc:83:54: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                      ^
a.cc:83:60: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                            ^
a.cc:83:66: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                                  ^
a.cc:83:72: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                                        ^
a.cc:83:78: error: invalid types 'int[int]' for array subscript
   83 |                                 auto p = find(x[i], y[i], x[j], y[j], x[k], y[k]);
      |                                                                              ^
a.cc:84:36: error: expected ';' before 'xr'
   84 |                                 lld xr = p.first;
      |                                    ^~~
      |                                    ;
a.cc:85:36: error: expected ';' before 'yr'
   85 |                                 lld yr = p.second;
      |                                    ^~~
      |                                    ;
a.cc:86:36: error: expected ';' before 'res'
   86 |                                 lld res = 0;
      |                                    ^~~~
      |                                    ;
a.cc:89:41: error: 'res' was not declared in this scope
   89 |                                         res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                         ^~~
a.cc:89:60: error: 'xr' was not declared in this scope; did you mean 'x'?
   89 |                                         res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                            ^~
      |                                                            x
a.cc:89:66: error: invalid types 'int[int]' for array subscript
   89 |                                         res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                                  ^
a.cc:89:56: error: 'sqr' was not declared in this scope; did you mean 'sqrt'?
   89 |                                         res = max(res, sqr(xr - x[l]) + sqr(yr - y[l]));
      |                                                        ^~~
      |