Language: C++

//nonsence
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<(int)(n); ++i)
using namespace std;

vector<vector<bool>> seen;
vector<vector<int>> todo;

void bfs(const vector<vector<int>> &G, int v){
  seen[v] = true;
  todo.push_back(v);
  int x = todo[0];
  todo.erase(todo.begin());
  for(auto next_v : G[x]){
    if(seen[next_v] == true) continue;
    bfs(G, next_v);
  }
}

int main(){
  int N;
  cin >> N;
  vector<vector<int>> G(N-1);
  rep(i, N-1){
    int a, b;
    cin >> a >> b;
    G[a-1].push_back(b-1);
    G[b-1].push_back(a-1);
  }
  
}

Compiler output:
a.cc: In function 'void bfs(const std::vector<std::vector<int> >&, int)':
a.cc:10:13: error: no match for 'operator=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} and 'bool')
   10 |   seen[v] = true;
      |             ^~~~
In file included from /usr/include/c++/14/vector:67,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_bvector.h:894:7: note: candidate: 'std::vector<bool, _Alloc>& std::vector<bool, _Alloc>::operator=(const std::vector<bool, _Alloc>&) [with _Alloc = std::allocator<bool>]'
  894 |       operator=(const vector& __x)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_bvector.h:894:31: note:   no known conversion for argument 1 from 'bool' to 'const std::vector<bool>&'
  894 |       operator=(const vector& __x)
      |                 ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_bvector.h:926:7: note: candidate: 'std::vector<bool, _Alloc>& std::vector<bool, _Alloc>::operator=(std::vector<bool, _Alloc>&&) [with _Alloc = std::allocator<bool>]'
  926 |       operator=(vector&& __x) noexcept(_Bit_alloc_traits::_S_nothrow_move())
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_bvector.h:926:26: note:   no known conversion for argument 1 from 'bool' to 'std::vector<bool>&&'
  926 |       operator=(vector&& __x) noexcept(_Bit_alloc_traits::_S_nothrow_move())
      |                 ~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_bvector.h:952:7: note: candidate: 'std::vector<bool, _Alloc>& std::vector<bool, _Alloc>::operator=(std::initializer_list<bool>) [with _Alloc = std::allocator<bool>]'
  952 |       operator=(initializer_list<bool> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_bvector.h:952:40: note:   no known conversion for argument 1 from 'bool' to 'std::initializer_list<bool>'
  952 |       operator=(initializer_list<bool> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:11:17: error: no matching function for call to 'std::vector<std::vector<int> >::push_back(int&)'
   11 |   todo.push_back(v);
      |   ~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; value_type = std::vector<int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:35: note:   no known conversion for argument 1 from 'int' to 'const std::vector<std::vector<int> >::value_type&' {aka 'const std::vector<int>&'}
 1283 |       push_back(const value_type& __x)
      |                 ~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; value_type = std::vector<int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:30: note:   no known conversion for argument 1 from 'int' to 'std::vector<std::vector<int> >::value_type&&' {aka 'std::vector<int>&&'}
 1300 |       push_back(value_type&& __x)
      |                 ~~~~~~~~~~~~~^~~
a.cc:12:17: error: cannot convert '__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> >, std::vector<int> >::value_type' {aka 'std::vector<int>'} to 'int' in initialization
   12 |   int x = todo[0];
      |                 ^
a.cc:15:21: error: no match for 'operator==' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} and 'bool')
   15 |     if(seen[next_v] == true) continue;
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1199:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'bool'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'bool'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<bool> >, std::vector<bool> >::value_type' {aka 'std::vector<bool>'} is not derived from 'const std::pair<_T1, _T2>'
   15 |     if(seen[next_v] == true) continue;
      |                        ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl