import java.util.*;

public class AdjacentListGraph {

public class Edge {

int from;

int to;

int weight;

public Edge(int from, int to, int weight){

this.from = from;

this.to = to;

this.weight = weight;

}

}

Map<Integer, List<Edge>> adjacentList;

int V;

public AdjacentListGraph (int V) {

this.V = V;

adjacentList = new HashMap<>();

for (int i = 0; i < V; i ++) {

adjacentList.put(i, new LinkedList<Edge>());

}

}

public void addEdge(int from, int to, int weight) {

List<Edge> adjacentEdge = adjacentList.get(from);

if (adjacentEdge != null) {

adjacentEdge.add(new Edge(from, to, weight));

}

}

public void printGraph(){

for (int vertex = 0; vertex < V; vertex ++ ) {

List<Edge> adjacentEdge = adjacentList.get(vertex);

for (Edge edge: adjacentEdge) {

System.out.println("Edge from " + edge.from + " to " + edge.to + " weight = " + edge.weight);

}

}

}

}