CJDUTIEC (lqdoj) - Dijkstra

// https://lqdoj.edu.vn/problem/CJDUTIEC
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pi32 = pair<int, int>;
using pi64 = pair<int64_t, int64_t>;
using ti32 = tuple<int, int, int>;
using ti64 = tuple<int64_t, int64_t, int64_t>;

const int N = 1e5 + 5;
const int INF = 1e18 + 7;

int n, nE, s, t;
vector<pi32> graph[N];

int64_t d[N];
int parent[N];

void Dijkstra(int s) {
    fill(parent + 1, parent + n + 1, -1);
    fill(d + 1, d + n + 1, INF);
    d[s] = 0;
    priority_queue<pi64, vector<pi64>, greater<pi64>> pq;
    pq.push({0, s});

    while (!pq.empty()) {
        const auto [du, u] = pq.top(); pq.pop();

        if (d[u] > du) continue;

        for (const auto &[uv, v] : graph[u]) {
            if (d[v] > d[u] + uv) {
                d[v] = d[u] + uv;
                parent[v] = u;
                pq.push({d[v], v});
            }
        }
    }
}

int main() {
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
#else
    freopen("CJDUTIEC.inp", "r", stdin);
    freopen("CJDUTIEC.out", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n >> nE >> s >> t;

    for (int i = 1; i <= nE; i++) {
        int u, v, w; cin >> u >> v >> w;
        graph[u].push_back({w, v});
        graph[v].push_back({w, u});
    }

    Dijkstra(s);

    vector<int> path;
    int u = t;
    while (u != -1) {
        path.push_back(u);
        u = parent[u];
    }

    cout << d[t] << '\n';
    reverse(path.begin(), path.end());
    for (int u : path)
        cout << u << ' ';

    return 0;
}