Language: C++

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

using namespace std;

int V, E, A, B;

vector<vector<int> > G;

vector<int> T;

vector<bool> used;

void rec(int u)
{
	used[u] = true;

	for (int i = 0; i < G[u].size(); i++)
	{
		int v = G[u][i];

		if (!used[v]) { rec(v); }
	}

	T.push_back(u);
}

int main()
{
	scanf("%d", &V);
	scanf("%d", &E);

	G = vector<vector<int> >(V);

	for (int i = 0; i < E; i++)
	{
		scanf("%d", &A);
		scanf("%d", &B);

		G[A - 1].push_back(B - 1);
	}

	used = vector<bool>(V, false);

	for (int i = 0; i < V; i++)
	{
		if (!used[i])
		{
			rec(i);
		}
	}

	reverse(T.begin(), T.end());

	for (int i = 0; i < T.size(); i++)
	{
		printf("%d\n", T[i] + 1);
	}

	bool ok = true;

	for (int i = 1; i < V; i++)
	{
		if (!binary_search(G[T[i - 1]].begin(), G[T[i - 1]].end(), G[T[i]]))
		{
			ok = false;
		}
	}

	return 0;
}

Compiler output:
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h: In instantiation of 'bool std::binary_search(_FIter, _FIter, const _Tp&) [with _FIter = __gnu_cxx::__normal_iterator<int*, vector<int> >; _Tp = vector<int>]':
a.cc:65:21:   required from here
   65 |                 if (!binary_search(G[T[i - 1]].begin(), G[T[i - 1]].end(), G[T[i]]))
      |                      ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:2207:39: error: no match for 'operator<' (operand types are 'const std::vector<int>' and 'int')
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/vector:62,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::pair<_T1, _T2>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::reverse_iterator<_Iterator>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::reverse_iterator<_Iterator>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::move_iterator<_IteratorL>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::move_iterator<_IteratorL>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:2089:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator<(const vector<_Tp, _Alloc>&, const vector<_Tp, _Alloc>&)'
 2089 |     operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:2089:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   mismatched types 'const std::vector<_Tp, _Alloc>' and 'int'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/vector:87:
/usr/include/c++/14/tuple:2600:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2600 |     operator<(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2600:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::tuple<_UTypes ...>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 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:2:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'std::vector<int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'std::vector<int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3888 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   'const std::vector<int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3901 |     operator<(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_algo.h:2207:39: note:   mismatched types 'const _CharT*' and 'std::vector<int>'
 2207 |       return __i != __last && !(__val < *__i);
      |                                ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/ios_base.h:46:
/usr/include/c++/14/system_error:324:3: note: candidate: 'bool std::operator<(const error_code&, const error_code&)'
  324 |   operator<(const error_code& __lhs, const error_code& __rhs) noexcept
      |   ^~~~~~~~
/usr/include/c++/14/system_error:324:31: note:   no known conversion for argument 1 from 'const std::vector<int>' to 'cons