ЗОШ Dijkstra OK

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
#define vec vector
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x+1<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}
struct ed{
    int fr, to, w;
};

const int inf = 2e9;

int n,m,s,f;
vec <vec <ed>> G;
vec <int> d;
vec <int> pr;

set <pii> Q;

vector <bool> was;

void Dij(int s){
    d.assign(n, inf);
    pr.assign(n, -1);
    Q.insert({0, s});
    was.assign(n, 0);
    d[s] = 0;
    while (!Q.empty()){
        int v = Q.begin() -> second;
        Q.erase(Q.begin());
        //was[v] = 1;
        for (ed e: G[v]){
            //if (was[e.to]) continue;
            if (d[e.to] > d[v] + e.w){
                Q.erase({d[e.to], e.to});
                d[e.to] = d[v] + e.w;
                pr[e.to] = v;

                Q.insert({d[e.to], e.to});
            }
        }
    }
}

int main()
{
    ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m>>s>>f;
	--s;
	--f;
	G.resize(n);
	for (int i=0;i<m;++i){
        int a,b,w;
        cin>>a>>b>>w;
        a--;
        b--;
        G[a].push_back({a, b, w});
        G[b].push_back({b, a, w});
	}
	Dij(s);
	if (d[f] == inf) {
        cout<<-1;
        exit(0);
	}
	cout<<d[f]<<"\n";
	int v=f;
	vec <int> way ;
	while (v>=0){
        way.push_back(v);
        v = pr[v];
	}
	reverse(way.begin(), way.end());
	//cv(way);
}