Language: C++

#include<bits/stdc++.h>

using namespace std;

int main(void) {
    long n;
    cin >> n;
    
    constexpr double eps = 1e-11;
    using P = complex<double>;

    vector<P> xy(n);
    for(auto &t: xy) {
        double r, i;
        cin >> r >> i;
        t.real(r);
        t.imag(i);
    }

    double r = 1e15;

    for(int i=0; i<n; i++)
        for(int j=i+1; j<n; j++)
            for(int k=j+1; k<n; k++) {
                P pa = xy[i], pb = xy[j], pc = xy[k];
                double a = dis(pb, pc), b = dis(pc, pa), c = dis(pa, pb);

                P pu = ((pa - pb)*norm(pc) + (pb - pc)*norm(pa) + (pc - pa)*norm(pb)) / ((pa-pb)*conj(pc) + (pb-pc)*conj(pa) + (pc-pa)*conj(pb));

                double d = max(norm(pa-pu), max(norm(pb-pu), norm(pc-pu)));

                for(int l=0; l<n; l++) {
                    if(norm(xy[l] - pu) > d+eps)
                        goto bad;
                }

                r = min(d, r);
bad:
                continue;
            }

    for(int i=0; i<n; i++)
        for(int j=i+1; j<n; j++) {
            P pa = xy[i], pb = xy[j];
            P pu = (pa+pb)/2;

            double d = max(norm(pa-pu), norm(pb-pu));

            for(int l=0; l<n; l++) {
                if(norm(xy[l]-pu) > d+eps)
                    goto bad2;
            }

            r = min(d, r);
bad2:
            continue;
        }

    cout << setprecision(16) << sqrt(r) << endl;

}


Compiler output:
a.cc: In function 'int main()':
a.cc:26:28: error: 'dis' was not declared in this scope; did you mean 'div'?
   26 |                 double a = dis(pb, pc), b = dis(pc, pa), c = dis(pa, pb);
      |                            ^~~
      |                            div
a.cc:45:27: error: no match for 'operator/' (operand types are 'std::complex<double>' and 'int')
   45 |             P pu = (pa+pb)/2;
      |                    ~~~~~~~^~
      |                       |    |
      |                       |    int
      |                       std::complex<double>
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/complex:430:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const complex<_Tp>&)'
  430 |     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:430:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/complex:439:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const _Tp&)'
  439 |     operator/(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:439:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   deduced conflicting types for parameter 'const _Tp' ('double' and 'int')
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/complex:448:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const complex<_Tp>&)'
  448 |     operator/(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:448:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   45 |             P pu = (pa+pb)/2;
      |                            ^
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:408:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   'std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   'std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   'std::complex<double>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   'std::complex<double>' is not derived from 'const std::valarray<_Tp>'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   'std::complex<double>' is not derived from 'const std::valarray<_Tp>'
   45 |             P pu = (pa+pb)/2;
      |                            ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:45:28: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   45 |             P pu = (pa+pb)/2;
      |                            ^