Language: C++

#include <bits/stdc++.h>
using namespace std;

using point = complex<long double>;

int main() {
    int n; cin >> n;
    vector<point> ps;
    for(int i = 0; i < n; ++i) {
        int x, y; cin >> x >> y;
        if(x == 0 && y == 0) continue;
        ps.emplace_back(x, y);
    }
    n = ps.size();
    sort(ps.begin(), ps.end(),
         [] (auto const& a, auto const& b) { return arg(a) < arg(b); });

    double ans = 0;
    for(int i = 0; i < n; ++i) {
        point p = ps[i];
        ans = max(ans, abs(p));
        for(int j = 1; j < n; ++j) {
            auto const v = ps[(i + j) % n];
            if(arg(v / ps[i]) < 0) break;
            p += v;
            ans = max(ans, abs(p));
        }
    }

    cout << fixed << setprecision(12) << ans << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:21:18: error: no matching function for call to 'max(double&, long double)'
   21 |         ans = max(ans, abs(p));
      |               ~~~^~~~~~~~~~~~~
In file included 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_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:21:18: note:   deduced conflicting types for parameter 'const _Tp' ('double' and 'long double')
   21 |         ans = max(ans, abs(p));
      |               ~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:21:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'double'
   21 |         ans = max(ans, abs(p));
      |               ~~~^~~~~~~~~~~~~
a.cc:26:22: error: no matching function for call to 'max(double&, long double)'
   26 |             ans = max(ans, abs(p));
      |                   ~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:26:22: note:   deduced conflicting types for parameter 'const _Tp' ('double' and 'long double')
   26 |             ans = max(ans, abs(p));
      |                   ~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:26:22: note:   mismatched types 'std::initializer_list<_Tp>' and 'double'
   26 |             ans = max(ans, abs(p));
      |                   ~~~^~~~~~~~~~~~~