Language: C++

#include <iostream>
#include <vector>
using namespace std;
int main(){
  int n;
  cin >> n;
  vector<int> p[n];
  for(int i = 0; i < n-1; i++){
    int a, b;
    cin >> a >> b;
    p[a].push_back(b);
    p[b].push_back(a);
  }
  vector<int> q[n];
  for(int i = 0; i < n; i++){
    for(int j = 0; j < p[i].size(); j++){
      for(int k = 0; k < p[p[i][j]].size(); k++){
        for(int l = 0; l < p[p[p[i][j]][k]].size(); l++){
          q[i].push_back(p[p[p[i][j]][k]][l]);
        }
      }
    }
  }
  int Qcount[n];
  for(int i = 0; i < n; i++){
    Qcount[i] = 0;
    Qcount[i]+= q[i].size();
  }
  vector<int> N[n];
  for(int i = 0; i < n; i++){
    for(int j = 0; j < n; j++){
      if(i*j%3==0||(i+j)%3==0)N[i].push_back(j);
    }
  }
  int Ncount[n];
  for(int i = 0; i < n; i++){
    Ncount[i] = 0;
    Ncount[i]+= N[i].size();
  }
  int ans[n];
  int check = 0;
  for(int i = 0; i < n; i++)ans[i] = i;
  for(int i = 0; i < n; i++){
    if(Ncount[i]<Qcount[i]){
      for(int j = n-1; j > i; j--){
        if(Ncount[j]>=Qcount[i]&&Qcount[j]<Qcount[i]){
          swap(ans[i], ans[j]);
        }
        check++;
      }
    }
  }
  for(int i = 0; i < n; i++){
    cout << ans[i] < ' ';
  }
  if(check == 0)cout << -1 << endl;
  return 0;
}



Compiler output:
a.cc: In function 'int main()':
a.cc:54:20: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and 'char')
   54 |     cout << ans[i] < ' ';
      |     ~~~~~~~~~~~~~~ ^ ~~~
      |          |           |
      |          |           char
      |          std::basic_ostream<char>
a.cc:54:20: note: candidate: 'operator<(int, int)' (built-in)
   54 |     cout << ans[i] < ' ';
      |     ~~~~~~~~~~~~~~~^~~~~
a.cc:54:20: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to '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: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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   54 |     cout << ans[i] < ' ';
      |                      ^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   54 |     cout << ans[i] < ' ';
      |                      ^~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   54 |     cout << ans[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:
a.cc:54:22: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'char'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   54 |     cout << ans[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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   54 |     cout << ans[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:
a.cc:54:22: note:   mismatched types 'const _CharT*' and 'std::basic_ostream<char>'
   54 |     cout << ans[i] < ' ';
      |                      ^~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68:
/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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::tuple<_UTypes ...>'
   54 |     cout << ans[i] < ' ';
      |                      ^~~
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:2:
/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:
a.cc:54:22: note:   'std::basic_ostream<char>' is not derived from 'const std::vector<_Tp, _Alloc>'
   54 |     cout << ans[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 'std::basic_ostream<char>' to 'const std::error_code&'
  324 |   operator<(const error_code& __lhs, const error_code& __rhs) noexcept
      |             ~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/system_error:507:3: note: candidate: 'bool std::operator<(const error_condition&, const error_condition&)'
  507 |   operator<(const error_condition& __lhs,
      |   ^~~~~~~~
/usr/include/c++/14/system_error:507:36: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to 'const std::error_condition&'
  507 |   operator<(const error_condition& __lhs,
      |             ~~~~~~~~~~~~~~~~~~~~~~~^~~~~