1using System;
2using System.Collections.Generic;
3
4public class Graph {
5    private int n;
6    private List<List<(int, int)>> adj;
7
8    public Graph(int n, int[][] edges) {
9        this.n = n;
10        this.adj = new List<List<(int, int)>>();
11        for (int i = 0; i < n; i++) {
12            adj.Add(new List<(int, int)>());
13        }
14        foreach (var edge in edges) {
15            adj[edge[0]].Add((edge[1], edge[2]));
16        }
17    }
18
19    public void AddEdge(int[] edge) {
20        adj[edge[0]].Add((edge[1], edge[2]));
21    }
22
23    public int ShortestPath(int node1, int node2) {
24        int[] dist = new int[n];
25        Array.Fill(dist, int.MaxValue);
26        dist[node1] = 0;
27
28        var pq = new SortedSet<(int Distance, int Vertex)>(Comparer<(int, int)>.Create((x, y) => {
29            int result = x.Distance.CompareTo(y.Distance);
30            return result == 0 ? x.Vertex.CompareTo(y.Vertex) : result;
31        }));
32        pq.Add((0, node1));
33
34        while (pq.Count > 0) {
35            var current = pq.Min;
36            pq.Remove(current);
37            int u = current.Vertex;
38            int curDist = current.Distance;
39
40            if (u == node2) return curDist;
41            if (curDist > dist[u]) continue;
42
43            foreach (var (v, cost) in adj[u]) {
44                if (dist[u] + cost < dist[v]) {
45                    dist[v] = dist[u] + cost;
46                    pq.Add((dist[v], v));
47                }
48            }
49        }
50        return -1;
51    }
52
53    public static void Main() {
54        int[][] edges = new int[][] { new int[] { 0, 2, 5 }, new int[] { 0, 1, 2 }, new int[] { 1, 2, 1 }, new int[] { 3, 0, 3 } };
55        Graph g = new Graph(4, edges);
56        Console.WriteLine(g.ShortestPath(3, 2)); // Output: 6
57        Console.WriteLine(g.ShortestPath(0, 3)); // Output: -1
58        g.AddEdge(new int[] { 1, 3, 4 });
59        Console.WriteLine(g.ShortestPath(0, 3)); // Output: 6
60    }
61}