Dijkstra

#include <bits/stdc++.h>

using namespace std;

#define OO 10000000

int n, m;
vector<vector<pair<int, int>>> G;

int dijkstra(int source, int dst) {
    vector<int> dist(n + 2, OO);
    priority_queue<pair<int, int>> pq;

    dist[source] = 0;
    pq.push({0, source});

    while(!pq.empty()) {
        auto [d, v] = pq.top();
        d *= -1;
        pq.pop();
        if(d > dist[v])
            continue;
        for(auto [u, cost] : G[v]) {
            if(dist[u] > dist[v] + cost) {
                dist[u] = dist[v] + cost;
                pq.push({-dist[u], u});
            }
        }
    }
    return dist[dst];
}

int main(){
    cin >> n >> m;

    G.resize(n + 2);
    for(int i = 0; i < m; ++i) {
        int u, v, w;
        cin >> u >> v >> w;
        G[u].push_back({v, w});
        G[v].push_back({u, w});
    }

    cout << dijkstra(0, n + 1) << '\n';

    return 0;
}