Language: C++

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int median(int a[], int N) {
    return a[int(N / 2)];
}


int main() {
    int N, K;
    cin >> N;

    int a[N];
    for (int i=0; i<N; i++) {
        cin >> a[i];
    }

    sort(a, a+N);

    vector<int> sub;
    for (int i=0; i<N; i++) {
        for (int j=0; j<=i; j++) {
            sub.push_back(a[j]);
        }
    }

    sort(sub, sub+sub.size());
    cout << median(sub, sub.size()) << "\n";

    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:30:18: error: no match for 'operator+' (operand types are 'std::vector<int>' and 'std::vector<int>::size_type' {aka 'long unsigned int'})
   30 |     sort(sub, sub+sub.size());
      |               ~~~^~~~~~~~~~~
      |               |           |
      |               |           std::vector<int>::size_type {aka long unsigned int}
      |               std::vector<int>
In file included from /usr/include/c++/14/string:48,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   30 |     sort(sub, sub+sub.size());
      |                            ^
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'const _CharT*' and 'std::vector<int>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'const _CharT*' and 'std::vector<int>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3733:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*)'
 3733 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
/usr/include/c++/14/bits/basic_string.h:3740:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, _CharT)'
 3740 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3740:5: note:   template argument deduction/substitution failed:
a.cc:30:28: note:   'std::vector<int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   30 |     sort(sub, sub+sub.size());
      |                            ^
a.cc:31:20: error: cannot convert 'std::vector<int>' to 'int*'
   31 |     cout << median(sub, sub.size()) << "\n";
      |                    ^~~
      |