Language: C++

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <iomanip>
#include <cmath>
#include <random>
using namespace std;
class xor128{
  public:
    unsigned operator()(){ return random(); }
    xor128(){ random_device rd; w = rd(); }
    xor128(unsigned s){ w = s; }
  private:
    unsigned x=123456789u,y=362436069u,z=521288629u,w;
    unsigned random() {
      unsigned t;
      t = x ^ (x << 11);
      x = y; y = z; z = w;
      return w = (w ^ (x >> 19)) ^ (t ^ (t >> 8));
    }
};

int n;
double x[100], y[100];

int main() {
  cin.tie(0); ios_base::sync_with_stdio(false);
  cin >> n;
  for(int i = 0; i < n; ++i) cin >> x[i] >> y[i];

  double ans = 0.0;
  xor128 xs = 1;
  uniform_real_distribution<double> real(-1.0, 1.0);
  for(int unko = 0; unko < 10000; ++unko) {
    x[n] = real(xs), y[n] = real(xs);

    double px = 0.0, py = 0.0;
    for(int i = 0; i < n; ++i)
      if(x[i]*x[n] + y[i]*y[n] >= 0) px += x[i], py += y[i];
    ans = max(ans, px*px + py*py);
  }
  cout << fixed << setprecision(15) << sqrt(ans);
  return 0;
}

Compiler output:
In file included from /usr/include/c++/14/random:50,
                 from a.cc:7:
/usr/include/c++/14/bits/random.tcc: In instantiation of '_RealType std::generate_canonical(_UniformRandomNumberGenerator&) [with _RealType = double; long unsigned int __bits = 53; _UniformRandomNumberGenerator = xor128]':
/usr/include/c++/14/bits/random.h:295:38:   required from '_DInputType std::__detail::_Adaptor<_Engine, _DInputType>::operator()() [with _Engine = xor128; _DInputType = double]'
  293 |           return std::generate_canonical<_DInputType,
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  294 |                                     std::numeric_limits<_DInputType>::digits,
      |                                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  295 |                                     _Engine>(_M_g);
      |                                     ~~~~~~~~^~~~~~
/usr/include/c++/14/bits/random.h:2011:19:   required from 'std::uniform_real_distribution<_RealType>::result_type std::uniform_real_distribution<_RealType>::operator()(_UniformRandomNumberGenerator&, const param_type&) [with _UniformRandomNumberGenerator = xor128; _RealType = double; result_type = double]'
 2011 |           return (__aurng() * (__p.b() - __p.a())) + __p.a();
      |                   ~~~~~~~^~
/usr/include/c++/14/bits/random.h:2002:34:   required from 'std::uniform_real_distribution<_RealType>::result_type std::uniform_real_distribution<_RealType>::operator()(_UniformRandomNumberGenerator&) [with _UniformRandomNumberGenerator = xor128; _RealType = double; result_type = double]'
 2002 |         { return this->operator()(__urng, _M_param); }
      |                  ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
a.cc:36:16:   required from here
   36 |     x[n] = real(xs), y[n] = real(xs);
      |            ~~~~^~~~
/usr/include/c++/14/bits/random.tcc:3357:63: error: 'class xor128' has no member named 'max'
 3357 |       const long double __r = static_cast<long double>(__urng.max())
      |                                                        ~~~~~~~^~~
/usr/include/c++/14/bits/random.tcc:3358:63: error: 'class xor128' has no member named 'min'
 3358 |                             - static_cast<long double>(__urng.min()) + 1.0L;
      |                                                        ~~~~~~~^~~
/usr/include/c++/14/bits/random.tcc:3367:48: error: 'class xor128' has no member named 'min'
 3367 |           __sum += _RealType(__urng() - __urng.min()) * __tmp;
      |                                         ~~~~~~~^~~