Language: C++

#include<bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(),(x).end()
typedef long long ll;
#define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
#define REP(i,num,n) for(ll i=num, i##_len=(n); i<i##_len; ++i)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
const ll LLINF = 1LL<<60;
const int INTINF = 1<<30;
const int MOD = 1000000007;

void add(long long &a, long long b) {
  a += b;
  if (a >= MOD) a -= MOD;
}

const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

using Edge = pair<int, ll>;
using Graph = vector<vector<Edge> >;

void rec(const Graph &G, int v, int p, ll sum, vector<ll> &dist){
  dist[v] = sum;
  for(auto e : G[v]){
    if(e.first == p) continue;
    rec(G, e.first, v, sum+e.second, dist);
  }
}

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);
    Graph(N);
    rep(i,N-1){
      int a,b; ll c; cin >> a >> b >> c;
      --a,--b;
      G[a].push_back({b,c});
      G[b].push_back({a,c});
    }
    int Q, K; cin >> Q >> K; --K;
    vector<ll> dist(N, 0);
    rec(G,K,-1,0,dist);

    rep(q,Q){
      int x,y;
      cin >> x >> y;
      --x,--y;
      cout << dist[x] + dist[y] << endl;
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:38:12: error: no match for 'operator-' (operand types are 'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} and 'int')
   38 |     rep(i,N-1){
      |           ~^~
      |           | |
      |           | int
      |           Graph {aka std::vector<std::vector<std::pair<int, long long int> > >}
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:618:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__y.base() - __x.base())) std::operator-(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  618 |     operator-(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:618:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::reverse_iterator<_Iterator>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__x.base() - __y.base())) std::operator-(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1790 |     operator-(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::move_iterator<_IteratorL>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/complex:370:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const complex<_Tp>&)'
  370 |     operator-(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:370:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::complex<_Tp>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/complex:379:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const _Tp&)'
  379 |     operator-(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:379:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::complex<_Tp>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/complex:388:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const _Tp&, const complex<_Tp>&)'
  388 |     operator-(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:388:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/complex:465:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&)'
  465 |     operator-(const complex<_Tp>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:465:5: note:   candidate expects 1 argument, 2 provided
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
      |                                       ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const valarray<_Tp>&, const valarray<_Tp>&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'Graph' {aka 'std::vector<std::vector<std::pair<int, long long int> > >'} is not derived from 'const std::valarray<_Tp>'
   38 |     rep(i,N-1){
      |             ^
a.cc:5:39: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(ll i=0, i##_len=(n); i