Language: C++

#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
const int N=(1e5);

vector<int> G[N+5];
vector<ll> C[N+5];

struct Node{
	int u;
  	ll d;
  	Node(){}
  	Node(int _u,ll _d){
    	u = _u;
      	d = _d;
    }
};

bool operator < (const &Node a,const &Node b){
	return a.d > b.d;
}
int n;
const ll INF=(1e18);

vector<ll> djistra(int source){
	vector<ll> ans(n,INF);
  	ans[source-1] = 0;
  	priority_queue<Node> Q;
    Q.push(Node(source,0));
  	while(!Q.empty()){
    	Node p = Q.top();
      	Q.pop();
      	int nodo = p.u;
      	int dist = p.d;
      	for(int i=0;i<G[nodo].size();i++){
        	int v = G[nodo][i];
          	int w = C[nodo][i];
          	if(ans[v-1] > dist + w){
              	ans[v-1] = dist + w;
            	Q.push(Node(v,dist+w));
            }
        }
    }
  	return ans;
}

int main(){
  cin>>n;
  int a,b;
  ll c;
  for(int i=1;i<n;i++){
  	cin>>a>>b>>c;
    G[a].push_back(b);
    G[b].push_back(a);
    C[a].push_back(c);
    C[b].push_back(c);
  }
  int q,k;cin>>q>>k;
  vector<ll> d = djistra(k);
  while(q--){
  	cin>>a>>b;
    cout<<d[a-1]+d[b-1]<<'\n';
  }
}


Compiler output:
a.cc:20:25: error: ISO C++ forbids declaration of 'Node' with no type [-fpermissive]
   20 | bool operator < (const &Node a,const &Node b){
      |                         ^~~~
a.cc:20:30: error: expected ',' or '...' before 'a'
   20 | bool operator < (const &Node a,const &Node b){
      |                              ^
a.cc:20:6: error: 'bool operator<(const int&)' must have an argument of class or enumerated type
   20 | bool operator < (const &Node a,const &Node b){
      |      ^~~~~~~~
In file included from /usr/include/c++/14/string:49,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_function.h: In instantiation of 'constexpr bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Node]':
/usr/include/c++/14/bits/predefined_ops.h:196:23:   required from 'bool __gnu_cxx::__ops::_Iter_comp_val<_Compare>::operator()(_Iterator, _Value&) [with _Iterator = __gnu_cxx::__normal_iterator<Node*, std::vector<Node, std::allocator<Node> > >; _Value = Node; _Compare = std::less<Node>]'
  196 |         { return bool(_M_comp(*__it, __val)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:140:48:   required from 'void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Node*, vector<Node, allocator<Node> > >; _Distance = long int; _Tp = Node; _Compare = __gnu_cxx::__ops::_Iter_comp_val<less<Node> >]'
  140 |       while (__holeIndex > __topIndex && __comp(__first + __parent, __value))
      |                                          ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:216:23:   required from 'void std::push_heap(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<Node*, vector<Node, allocator<Node> > >; _Compare = less<Node>]'
  216 |       std::__push_heap(__first, _DistanceType((__last - __first) - 1),
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  217 |                        _DistanceType(0), _GLIBCXX_MOVE(__value), __cmp);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_queue.h:747:16:   required from 'void std::priority_queue<_Tp, _Sequence, _Compare>::push(value_type&&) [with _Tp = Node; _Sequence = std::vector<Node, std::allocator<Node> >; _Compare = std::less<Node>; value_type = Node]'
  747 |         std::push_heap(c.begin(), c.end(), comp);
      |         ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:30:11:   required from here
   30 |     Q.push(Node(source,0));
      |     ~~~~~~^~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_function.h:405:20: error: no match for 'operator<' (operand types are 'const Node' and 'const Node')
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
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: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:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const Node' is not derived from 'const std::pair<_T1, _T2>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/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:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const Node' is not derived from 'const std::reverse_iterator<_Iterator>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/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:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const Node' is not derived from 'const std::reverse_iterator<_Iterator>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/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:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const Node' is not derived from 'const std::move_iterator<_IteratorL>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/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:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const Node' is not derived from 'const std::move_iterator<_IteratorL>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~