main.cpp

#include <algorithm>
#include <iostream>
#include <limits>
#include <queue>
#include <string>
#include <utility>
#include <vector>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, start, target;
    if (!(cin >> n >> m >> start >> target)) {
        return 0;
    }
    vector<long long> supply(n + 1, 0);
    for (int i = 1; i <= n; ++i) {
        cin >> supply[i];
    }
    vector<vector<pair<int, int>>> graph(n + 1);
    for (int i = 0; i < m; ++i) {
        int u, v, w;
        cin >> u >> v >> w;
        graph[u].push_back({v, w});
        graph[v].push_back({u, w});
    }

    const long long INF = numeric_limits<long long>::max() / 4;
    vector<long long> dist(n + 1, INF);
    vector<int> prev(n + 1, -1);
    priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> pq;
    dist[start] = 0;
    pq.push({0, start});

    while (!pq.empty()) {
        auto [cost, node] = pq.top();
        pq.pop();
        if (cost != dist[node]) {
            continue;
        }
        for (auto [nxt, weight] : graph[node]) {
            long long new_cost = cost + weight + supply[nxt];
            if (new_cost < dist[nxt]) {
                dist[nxt] = new_cost;
                prev[nxt] = node;
                pq.push({new_cost, nxt});
            }
        }
    }

    if (dist[target] == INF) {
        cout << "min_cost=-1\n";
        cout << "path=IMPOSSIBLE\n";
        return 0;
    }

    vector<int> path;
    for (int cur = target; cur != -1; cur = prev[cur]) {
        path.push_back(cur);
    }
    reverse(path.begin(), path.end());
    cout << "min_cost=" << dist[target] << "\n";
    cout << "path=";
    for (size_t i = 0; i < path.size(); ++i) {
        if (i) {
            cout << "->";
        }
        cout << path[i];
    }
    cout << "\n";
    return 0;
}