Graph

import java.util.*;

public class Graph {
    private int vertices; // Number of vertices
    private LinkedList<Integer>[] adjacencyList;
    
    public Graph(int v) {
        vertices = v;
        adjacencyList = new LinkedList[v];
        for (int i = 0; i < v; i++) {
            adjacencyList[i] = new LinkedList<>();
        }
    }

    public void addEdge(int source, int destination) {
        adjacencyList[source].add(destination);
        adjacencyList[destination].add(source);
    }

    public void bfs(int startVertex) {
        boolean[] visited = new boolean[vertices];
        Queue<Integer> queue = new LinkedList<>();

        visited[startVertex] = true;
        queue.add(startVertex);

        while (!queue.isEmpty()) {
            int vertex = queue.poll();
            System.out.print(vertex + " ");

            for (int neighbor : adjacencyList[vertex]) {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    queue.add(neighbor);
                }
            }
        }
    }

    public static void main(String[] args) {
        Graph graph = new Graph(6);

        graph.addEdge(0, 1);
        graph.addEdge(0, 2);
        graph.addEdge(1, 3);
        graph.addEdge(1, 4);
        graph.addEdge(2, 4);
        graph.addEdge(3, 5);
        graph.addEdge(4, 5);

        System.out.println("BFS traversal starting from vertex 0:");
        graph.bfs(0);
    }
}