BFS_Arraylist.java

import java.util.*;

public class BFS_Arraylist {

	public static void main(String[] args) {
		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);
		printAdjacencyList(adj);

	}

	static void addEdge(ArrayList<ArrayList<Integer>> adj, int u, int v) {
		adj.get(u).add(v);
		adj.get(v).add(u);
	}

	static void printAdjacencyList(ArrayList<ArrayList<Integer>> adj) {
		for (int i = 0; i < adj.size(); i++) {
			System.out.println("Adjacency list of " + i);
			for (int j = 0; j < adj.get(i).size(); j++) {
				System.out.print(adj.get(i).get(j) + " ");
			}
			System.out.println();
		}
	}

}