Language: C++

#include "pch.h"

//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <string>
#include <cstring>
#include <ctime>
#include <limits>

using namespace std;

//conversion
//------------------------------------------
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v; }
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); }

//math
//-------------------------------------------
template<class T> inline T sqr(T x) { return x * x; }

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define EXISTch(s,c) ((((s).find_first_of(c)) != std::string::npos)? 1 : 0)//cがあれば1 if(1)
#define SORT(c) sort((c).begin(),(c).end())

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = (int)1000000007;
const LL MOD = (LL)1000000007;//10^9+7
const LL INF2 = (LL)100000000000000000;//10^18



template< typename T >
struct edge {
	int src, to;
	T cost;

	edge(int to, T cost) : src(-1), to(to), cost(cost) {}

	edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

	edge &operator=(const int &x) {
		to = x;
		return *this;
	}

	operator int() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WeightedGraph = vector< Edges< T > >;

template< typename T >
vector< T > dijkstra(WeightedGraph< T > &g, int s) {
	const auto INF = numeric_limits< T >::max();
	vector< T > dist(g.size(), INF);

	using Pi = pair< T, int >;
	priority_queue< Pi, vector< Pi >, greater< Pi > > que;
	dist[s] = 0;
	que.emplace(dist[s], s);
	while (!que.empty()) {
		T cost;
		int idx;
		tie(cost, idx) = que.top();
		que.pop();
		if (dist[idx] < cost) continue;
		for (auto &e : g[idx]) {
			auto next_cost = cost + e.cost;
			if (dist[e.to] <= next_cost) continue;
			dist[e.to] = next_cost;
			que.emplace(dist[e.to], e.to);
		}
	}
	return dist;
}

int main() {
	int V, E;
	cin >> V;
	E = V - 1;

	WeightedGraph< int > g(V);
	vector<int> x(E);
	vector<int> y(E);
	vector<int> z(E);
	for (int i = 0; i < E; i++) {
		cin >> x[i] >> y[i] >> z[i];
		//1indexedなら--して
		x[i]--; y[i]--;
		g[x[i]].emplace_back(y[i], z[i]);
		g[y[i]].emplace_back(x[i], z[i]);
	}

	int q, k; cin >> q >> k;
	k--;
	auto dist=dijkstra(g,k);

	for (int i = 0; i < q; i++) {
		int x, y; cin >> x >> y;
		x--; y--;

		cout << dist[x] + dist[y] << endl;
	}


	//dist == numeric_limits< int >::max()
	//for (auto &dist : dijkstra(g, R)) {

	//}
}

Compiler output:
a.cc:1:10: fatal error: pch.h: No such file or directory
    1 | #include "pch.h"
      |          ^~~~~~~
compilation terminated.