Language: C++

#include<bits/stdc++.h>
 
#define REP(i,s,N) for (int i=s;i<(N); ++i)
#define ALL(x) (x).begin(), (x).end()
typedef long long ll;
using namespace std;


ll ans=0;

int main(){
	ll N;
	cin >> N;
	ll a;
	vector<ll> L[N];
	REP(i,0,N){
	 cin >> a;
	 L.push_back(a);
	 }
	sort(L.begin(),L.end());
	REP(i,0,N-2){
		REP(j,0,N-1){
			auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
			ans += itr-(j+1);
		}
	}
	
	
	cout << ans << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:18:12: error: request for member 'push_back' in 'L', which is of non-class type 'std::vector<long long int> [N]'
   18 |          L.push_back(a);
      |            ^~~~~~~~~
a.cc:20:16: error: request for member 'begin' in 'L', which is of non-class type 'std::vector<long long int> [N]'
   20 |         sort(L.begin(),L.end());
      |                ^~~~~
a.cc:20:26: error: request for member 'end' in 'L', which is of non-class type 'std::vector<long long int> [N]'
   20 |         sort(L.begin(),L.end());
      |                          ^~~
a.cc:23:50: error: request for member 'begin' in 'L', which is of non-class type 'std::vector<long long int> [N]'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                  ^~~~~
a.cc:23:60: error: request for member 'end' in 'L', which is of non-class type 'std::vector<long long int> [N]'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                            ^~~
a.cc:23:70: error: no match for 'operator+' (operand types are 'std::vector<long long int>' and 'std::vector<long long int>')
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                  ~~~~^~~~~
      |                                                                     |    |
      |                                                                     |    vector<[...]>
      |                                                                     vector<[...]>
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 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_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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::move_iterator<_IteratorL>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   mismatched types 'const _CharT*' and 'std::vector<long long int>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:23:74: note:   'std::vector<long long int>' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   23 |                         auto itr = lower_bound(L.begin(),L.end(),L[i]+L[j]) - L.begin();
      |                                                                          ^
/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:371