Code:
import java.util.*;
public class Graph {
int V = 0;
int E = 0;
Set<Integer>[] adj;
public Graph(int V) {
this.V = V;
adj = (Set<Integer>[])new HashSet[V];
for(int i = 0; i < V; i++) {
adj[i] = new HashSet<>();
}
}
public int V() { return V;}
public int E() { return E;}
public void addEdge(int v, int w) {
adj[v].add(w);
adj[w].add(v);
E++;
}
public Iterable<Integer> adj(int v) {
return adj[v];
}
}
