Language: C++

#include <iostream>
#include <vector>
#define NIL -1
#define rep(i,a) for(i=0;i<a;i++)
using namespace std;

typedef struct{
  int parent;
  int left;
  int right;
}node;

vector<node> T;

int depth(int f){
  if(T[f].parent == NIL) return 0;
  return depth(T[f].parent)+1;
}

int sibling(int a){
  if(T[a].left) return NIL;
  if(T[T[a].parent].right == a) return T[T[a].parent].left;
  return T[T[a].parent].right;
}

int height(int o){
  int l = 0,r = 0;
  if(T[o].left == NIL && T[o].right == NIL) return 0;
  if(T[o].left != NIL)
    l = 1 + height(T[o].left);
  if(T[o].right != NIL)
    r = 1 + height(T[o].right);
  return l>r?l:r;
}

void print(int u){
    int d;
    cout << "node " << u << ": ";
    cout << "parent = " << T[u].parent << ", ";
    cout << "sibling = " << sibling(u) << ", ";
    cout << "degree = ";
    d = T[u].left == NIL && T[u].right == NIL?0:((T[u].left == NIL&&T[u].right != NIL) || (T[u].left != NIL && T[u].right == NIL)?1:2);
    cout << d << ", ";
    cout << "depth = " << depth(u) << ", ";
    cout << "height = " << height(u) << ", ";
    if(T[u] == NIL) cout << "root";
    else if( == NIL) cout << "leaf";
    else cout << "internal node";
}

int main(void){
    int i,n,v;

    cin >> n;
    T.resize(n);
    rep(i,n){
        T[i].parent = NIL;
        T[i].left = NIL;
        T[i].right = NIL;
    }
    rep(i,n){
        cin >> v >> T[v].left >> T[v].right;
        T[T[v].left].parent = v;
        T[T[v].right].parent = v;
    }
    rep(i,n){
        print(i);
    }
    return 0;
}

Compiler output:
a.cc: In function 'void print(int)':
a.cc:46:13: error: no match for 'operator==' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} and 'int')
   46 |     if(T[u] == NIL) cout << "root";
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::fpos<_StateT>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
In file included from /usr/include/c++/14/string:43,
                 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:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::allocator<_CharT>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::reverse_iterator<_Iterator>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::reverse_iterator<_Iterator>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::move_iterator<_IteratorL>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::move_iterator<_IteratorL>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
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: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:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::pair<_T1, _T2>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
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:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  629 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:629:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   'node' is not derived from 'std::basic_string_view<_CharT, _Traits>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/string_view:637:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  637 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:637:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   'node' is not derived from 'std::basic_string_view<_CharT, _Traits>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/string_view:644:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  644 |     operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:644:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/basic_string.h:3755:5: 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>&)'
 3755 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3755:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/basic_string.h:3772:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3772 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3772:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   '__gnu_cxx::__alloc_traits<std::allocator<node>, node>::value_type' {aka 'node'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
/usr/include/c++/14/bits/basic_string.h:3819:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3819 |     operator==(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3819:5: note:   template argument deduction/substitution failed:
a.cc:3:14: note:   mismatched types 'const _CharT*' and 'node'
    3 | #define NIL -1
      |              ^
a.cc:46:16: note: in expansion of macro 'NIL'
   46 |     if(T[u] == NIL) cout << "root";
      |                ^~~
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:2558:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std