bfs.java

/**
 * @author akshay
 */

import java.util.*;
import java.io.*;
public class bfs {

    
    public static void main(String[] args) {
        
        vertex a = new vertex("a");
        vertex b = new vertex("b");
        vertex c = new vertex("c");
        vertex d = new vertex("d");
        vertex e = new vertex("e");
        vertex f = new vertex("f");
        vertex g = new vertex("g");
        
        List<vertex> A = new ArrayList<vertex>(){{add(b); add(c);}};
        List<vertex> B = Arrays.asList(a,d,f,e);
        List<vertex> C = Arrays.asList(a);
        List<vertex> D = Arrays.asList(b);
        List<vertex> E = Arrays.asList(b,g);
        List<vertex> F = Arrays.asList(b);
        List <vertex>G = Arrays.asList(e);
        Map<String, List> adj = new Hashtable<String, List>();
        adj.put("a", A);
        adj.put("b", B);
        adj.put("c", C);
        adj.put("d", D);
        adj.put("e", E);
        adj.put("f", F);
        adj.put("g", G);    
        Queue <vertex> Q = new LinkedList<>();
        a.setColour("black");
        Q.add(a);
        while(Q.size() != 0)
        {
            vertex v = Q.remove();

            for(int i=0; i< adj.get(v.getName()).size(); i++){
                if(((vertex)adj.get(v.getName()).get(i)).getColour().equals("white"))
                {
                    ((vertex)adj.get(v.getName()).get(i)).setColour("gray");
                    Q.add(((vertex)adj.get(v.getName()).get(i)));
                    System.out.println(((vertex)adj.get(v.getName()).get(i)).getName());
                }
            }
            
            v.setColour("black");
        }
    
             
    }
    
}

class vertex{
    String name, colour;
    vertex(){};
    vertex(String name){
        this.name = name;
        colour = "white";
    }
    public void setColour(String c){
        this.colour = c;
    }
    public String getColour(){
        return this.colour;
    }
    public String getName(){
        return this.name;
    }
}