Print adjacency list Java

PROGRAM TO PRINT THE ADJACENCY LIST

import java.util.*;

 

class Graph {

     

    // A utility function to add an edge in an

    // undirected graph

    static void addEdge(ArrayList<ArrayList<Integer> > adj,

                        int u, int v)

    {

        adj.get(u).add(v);

        adj.get(v).add(u);

    }

 

    // A utility function to print the adjacency list

    // representation of graph

    static void printGraph(ArrayList<ArrayList<Integer> > adj)

    {

        for (int i = 0; i < adj.size(); i++) {

            System.out.println("\nAdjacency list of vertex" + i);

            System.out.print("head");

            for (int j = 0; j < adj.get(i).size(); j++) {

                System.out.print(" -> "+adj.get(i).get(j));

            }

            System.out.println();

        }

    }

 

    // Driver Code

    public static void main(String[] args)

    {

        // Creating a graph with 5 vertices

        int V = 5;

        ArrayList<ArrayList<Integer> > adj

                    = new ArrayList<ArrayList<Integer> >(V);

         

        for (int i = 0; i < V; i++)

            adj.add(new ArrayList<Integer>());

 

        // Adding edges one by one

        addEdge(adj, 0, 1);

        addEdge(adj, 0, 4);

        addEdge(adj, 1, 2);

        addEdge(adj, 1, 3);

        addEdge(adj, 1, 4);

        addEdge(adj, 2, 3);

        addEdge(adj, 3, 4);

         

        printGraph(adj);

    }

}







OUTPUT:

 Adjacency list of vertex 0
 head -> 1-> 4

 Adjacency list of vertex 1
 head -> 0-> 2-> 3-> 4

 Adjacency list of vertex 2
 head -> 1-> 3

 Adjacency list of vertex 3
 head -> 1-> 2-> 4

 Adjacency list of vertex 4
 head -> 0-> 1-> 3

CREDITS: https://www.geeksforgeeks.org/graph-and-its-representations/