Language: C++

#include<bits/stdc++.h>
using namespace std;
#define rep(i,j,n) for(int i=(int)(j);i<(int)(n);i++)
#define REP(i,j,n) for(int i=(int)(j);i<=(int)(n);i++)
#define MOD 1000000007
#define int long long
#define ALL(a) (a).begin(),(a).end()
#define vi vector<int>
#define vii vector<vi>
#define pii pair<int,int>
#define priq priority_queue<int>
#define disup(A,key) distance(A.begin(),upper_bound(ALL(A),(int)(key)))
#define dislow(A,key) distance(A.begin(),lower_bound(ALL(A),(int)(key)))
signed main(){
  int N,t,a; cin>>N>>t>>a;
  vii A(N);
  rep(i,0,N-1){
    int X,Y; cin>>X>>Y;
    A[X-1].push_back(Y-1);
    A[Y-1].push_back(X-1);
    }
  vi T(N,-1),A(N,-1);
  queue<int> Q;
  Q.push(t-1);
  Q.push(-1);
  int count=0;
  while(Q.size()>1){
    int K=Q.front();
    Q.pop();
    if(K==-1){
      count++;
      Q.push(-1);
      }
    else{
      T[K]=count;
      rep(i,0,A[K].size()){
        if(A[K][i]==-1)
          Q.push(A[K][i]);
        }
      }
    }
  count=0;
  Q.pop();
  Q.push(a-1);
  Q.push(-1);
  while(Q.size()>1){
    int K=Q.front();
    Q.pop();
    if(K==-1){
      count++;
      Q.push(-1);
      }
    else{
      A[K]=count;
      rep(i,0,A[K].size()){
        if(A[K][i]==-1)
          Q.push(A[K][i]);
        }
      }
    }
  int ans=0;
  rep(i,0,N){
    if(T[i]>=A[i])
      ans=max(ans,A[i]-1);
    }
  cout<<ans<<endl;
  }


Compiler output:
a.cc: In function 'int main()':
a.cc:22:14: error: conflicting declaration 'std::vector<long long int> A'
   22 |   vi T(N,-1),A(N,-1);
      |              ^
a.cc:16:7: note: previous declaration as 'std::vector<std::vector<long long int> > A'
   16 |   vii A(N);
      |       ^
a.cc:54:12: error: no match for 'operator=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type' {aka 'std::vector<long long int>'} and 'long long int')
   54 |       A[K]=count;
      |            ^~~~~
In file included from /usr/include/c++/14/vector:72,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/vector.tcc:210:5: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = long long int; _Alloc = std::allocator<long long int>]'
  210 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:211:42: note:   no known conversion for argument 1 from 'long long int' to 'const std::vector<long long int>&'
  211 |     operator=(const vector<_Tp, _Alloc>& __x)
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:766:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::vector<_Tp, _Alloc>&&) [with _Tp = long long int; _Alloc = std::allocator<long long int>]'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:766:26: note:   no known conversion for argument 1 from 'long long int' to 'std::vector<long long int>&&'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |                 ~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:788:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::initializer_list<_Tp>) [with _Tp = long long int; _Alloc = std::allocator<long long int>]'
  788 |       operator=(initializer_list<value_type> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:788:46: note:   no known conversion for argument 1 from 'long long int' to 'std::initializer_list<long long int>'
  788 |       operator=(initializer_list<value_type> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:63:12: error: no match for 'operator>=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'} and '__gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type' {aka 'std::vector<long long int>'})
   63 |     if(T[i]>=A[i])
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:1165:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator>=(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1165 |     operator>=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1165:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1248:5: 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>&)'
 1248 |     operator>=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1248:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1341:5: 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>&)'
 1341 |     operator>=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1341:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1415:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator>=(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1415 |     operator>=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1415:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type' {aka 'std::vector<long long int>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1509:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator>=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1509 |     operator>=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1509:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1586:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator>=(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1586 |     operator>=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1586:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type' {aka 'std::vector<long long int>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/regex.h:1686:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator>=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1686 |     operator>=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1686:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
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:1070:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator>=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1070 |     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1070:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::pair<_T1, _T2>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:476:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator>=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  476 |     operator>=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:476:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/stl_iterator.h:520:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator>=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  520 |     operator>=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:520:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'}
   63 |     if(T[i]>=A[i])
      |                 ^
/usr/include/c++/14/bits/stl_iterator.h:1724:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator>=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1724 |     operator>=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1724:5: note:   template argument deduction/substitution failed:
a.cc:63:17: note:   mismatched types 'const std::move_iterator<_IteratorL>' and '__gnu_cxx::__alloc_tra