Кратчайший путь

#include <bits/stdc++.h>

using namespace std;

const int N = 2e5 + 5;
const int inf = 2e9;

int n, m, s, t;
long long dist[N], par[N];
vector < pair <int, int> > g[N];

int main(){

    for (int i = 0; i < N; i++) {
        dist[i] = inf;
    }

    cin >> n >> m >> s >> t;

    for (int i = 1; i <= m; i++) {
        int u, v, len;
        cin >> u >> v >> len;
        g[u].push_back(make_pair(v, len));
        g[v].push_back(make_pair(u, len));
    }

    set < pair <int, int> > st;
    dist[s] = 0;
    st.insert({dist[s], s});

    while (!st.empty()) {
        int v = st.begin()->second;
        st.erase(st.begin());

        for (int i = 0; i < g[v].size(); i++) {
            int to = g[v][i].first, len = g[v][i].second;
            if (dist[v] + len < dist[to]) {
                st.erase({dist[to], to});
                dist[to] = dist[v] + len;
                par[to] = v;
                st.insert({dist[to], to});
            }
        }
    }

    if (dist[t] == inf) {
        cout << -1 << endl;
    } else {
        cout << dist[t] << endl;

        int x = t;
        vector <int> path;
        while (x != s) {
            path.push_back(x);
            x = par[x];
        }

        path.push_back(s);
        reverse(path.begin(), path.end());

        for (int x : path) {
            cout << x << " ";
        }
    }
}