Language: C++

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


using namespace std;


vector<pair<int, int>> len;

void dp(unordered_set<int>& visited, const vector<vector<int>>& matrix, int room, int depth)
{
	visited.insert(room);
	for (int a = 0; a < matrix[room].size(); ++a) {
		if (matrix[room][a] == 1) {
			if (len[a].first > depth + 1) {
				len[a].first = depth + 1;
				len[a].second = room + 1;
			}

			if (visited.find(a) == visited.end()) {
				dp(visited, matrix, a, depth + 1);
			}
		}
	}
}

int main()
{
	int n, m;
	cin >> n >> m;

	len = vector<pair<int, int>>(n, { INT_MAX, 0 });
	vector<vector<int>> matrix(n, vector<int>(n, 0));

	int A, B;
	for (int a = 0; a < m; ++a) {
		cin >> A >> B;
		matrix[A - 1][B - 1] = 1;
		matrix[B - 1][A - 1] = 1;
	}

	//for (int a = 0; a < matrix.size(); ++a) {
	//	for (int b = 0; b < matrix[a].size(); ++b) {
	//		cout << matrix[a][b] << ' ';
	//	}
	//	cout << '\n';
	//}


	

	for (int a = 0; a < matrix[0].size(); ++a) {
		if (matrix[0][a] == 1) {
			unordered_set<int> visited;
			len[a].first = 1;
			len[a].second = 1;
			dp(visited, matrix, a, 1);
		}
	}
	
	for (auto p : len) {
		if (p.second == 0) {
			cout << "No";
			return 0;
		}
	}

	cout << "Yes\n";
	for (int a = 1; a < len.size(); ++a) {
		cout << a + 1 << ' ' << len[a].second << '\n';
	}

	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:34:43: error: 'INT_MAX' was not declared in this scope
   34 |         len = vector<pair<int, int>>(n, { INT_MAX, 0 });
      |                                           ^~~~~~~
a.cc:5:1: note: 'INT_MAX' is defined in header '<climits>'; this is probably fixable by adding '#include <climits>'
    4 | #include <unordered_set>
  +++ |+#include <climits>
    5 | 
a.cc:34:55: error: no matching function for call to 'std::vector<std::pair<int, int> >::vector(int&, <brace-enclosed initializer list>)'
   34 |         len = vector<pair<int, int>>(n, { INT_MAX, 0 });
      |                                                       ^
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/bits/stl_iterator_base_funcs.h:66,
                 from /usr/include/c++/14/string:47,
                 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_base_types.h: In substitution of 'template<class _InIter> using std::_RequireInputIter = std::__enable_if_t<((bool)std::is_convertible<typename std::iterator_traits< <template-parameter-1-1> >::iterator_category, std::input_iterator_tag>::value)> [with _InIter = int]':
/usr/include/c++/14/bits/stl_vector.h:705:9:   required from here
  705 |                typename = std::_RequireInputIter<_InputIterator>>
      |                ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator_base_types.h:252:57: error: no type named 'iterator_category' in 'struct std::iterator_traits<int>'
  252 |                                    input_iterator_tag>::value>;
      |                                                         ^~~~~
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:43: note:   no known conversion for argument 1 from 'int' to 'std::initializer_list<std::pair<int, int> >'
  678 |       vector(initializer_list<value_type> __l,
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<int, int> >]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:23: note:   no known conversion for argument 1 from 'int' to 'std::vector<std::pair<int, int> >&&'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |              ~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<int, int> >]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:28: note:   no known conversion for argument 1 from 'int' to 'const std::vector<std::pair<int, int> >&'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |              ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; size_type = long unsigned int; value_type = std::pair<int, int>; allocator_type = std::allocator<std::pair<int, int> >]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:47: note:   no known conversion for argument 2 from '<brace-enclosed initializer list>' to 'const std::vector<std::pair<int, int> >::value_type&' {aka 'const std::pair<int, int>&'}
  569 |       vector(size_type __n, const value_type& __value,
      |                             ~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; size_type = long unsigned int; allocator_type = std::allocator<std::pair<int, int> >]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:51: note:   no known conversion for argument 2 from '<brace-enclosed initializer list>' to 'const std::vector<std::pair<int, int> >::allocator_type&' {aka 'const std::allocator<std::pair<int, int> >&'}
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |                             ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 2 provided