1import heapq
2
3class Graph:
4    def __init__(self, n, edges):
5        self.n = n
6        self.adj = [[] for _ in range(n)]
7        for u, v, cost in edges:
8            self.adj[u].append((v, cost))
9
10    def addEdge(self, edge):
11        u, v, cost = edge
12        self.adj[u].append((v, cost))
13
14    def shortestPath(self, node1, node2):
15        dist = [float('inf')] * self.n
16        dist[node1] = 0
17        pq = [(0, node1)]
18
19        while pq:
20            curDist, u = heapq.heappop(pq)
21            if u == node2:
22                return curDist
23            if curDist > dist[u]:
24                continue
25            for v, cost in self.adj[u]:
26                if dist[u] + cost < dist[v]:
27                    dist[v] = dist[u] + cost
28                    heapq.heappush(pq, (dist[v], v))
29        return -1
30
31# Demonstration
32if __name__ == "__main__":
33    edges = [[0, 2, 5], [0, 1, 2], [1, 2, 1], [3, 0, 3]]
34    graph = Graph(4, edges)
35    print(graph.shortestPath(3, 2))  # Output: 6
36    print(graph.shortestPath(0, 3))  # Output: -1
37    graph.addEdge([1, 3, 4])
38    print(graph.shortestPath(0, 3))  # Output: 6
39