BFS.java

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;

public class BFS {
    static class Edge{
        int source;
        int destination;

        public Edge(int source, int destination) {
            this.source = source;
            this.destination = destination;
        }
    }

    public static void CreateGraph(ArrayList<Edge> graph[]){
        for(int i = 0;i< graph.length;i++){
            graph[i] = new ArrayList<Edge>();
        }
        graph[0].add(new Edge(0,2 ));

        graph[1].add(new Edge(1,2));
        graph[1].add(new Edge(1,7));

        graph[2].add(new Edge(2,8));
        graph[2].add(new Edge(2,2));
        graph[2].add(new Edge(2,1));

        graph[3].add(new Edge(3,2));
        graph[3].add(new Edge(3,5));

    }
    public static void bfs(ArrayList<Edge> graph[], int V){
        Queue<Integer> q = new LinkedList<>();
        boolean visited[] = new boolean[V];
        q.add(0);
        while(!q.isEmpty()){
            int curr = q.remove();
            if(visited[curr] == false){
                System.out.println(curr+"");
                visited[curr] = true;

                for(int i = 0;i<graph[curr].size();i++){
                    Edge e = graph[curr].get(i);
                    q.add(e.destination);
                }
            }
        }
    }

    public static void main(String[] args) {
        int V = 9;
        ArrayList<Edge> graph[] = new ArrayList[V];
        CreateGraph(graph);
        bfs(graph,V);
        System.out.println();

    }
}