DepthfirsttraversalGraph.java

package com.geek;

import java.util.Iterator;
import java.util.LinkedList;

public class DepthfirsttraversalGraph {
	

    private int V;   // No. of vertices
 
    // Array  of lists for Adjacency List Representation
    private LinkedList<Integer> adj[];
 
    // Constructor
    DepthfirsttraversalGraph(int v)
    {
        V = v;
        adj = new LinkedList[v];
        for (int i=0; i<v; ++i)
            adj[i] = new LinkedList();
    }
 
    //Function to add an edge into the graph
    void addEdge(int v, int w)
    {
        adj[v].add(w);  // Add w to v's list.
    }
 
    // A function used by DFS
    void DFSUtil(int v,boolean visited[])
    {
        // Mark the current node as visited and print it
        visited[v] = true;
        System.out.print(v+" ");
 
        // Recur for all the vertices adjacent to this vertex
        Iterator<Integer> i = adj[v].listIterator();
        while (i.hasNext())
        {
            int n = i.next();
            if (!visited[n])
                DFSUtil(n, visited);
        }
    }
 
    // The function to do DFS traversal. It uses recursive DFSUtil()
    void DFS(int v)
    {
        // Mark all the vertices as not visited(set as
        // false by default in java)
        boolean visited[] = new boolean[V];
 
        // Call the recursive helper function to print DFS traversal
        DFSUtil(v, visited);
    }
	public static void main(String[] args) {
		
		DepthfirsttraversalGraph g = new DepthfirsttraversalGraph(4);
		 
	        g.addEdge(0, 1);
	        g.addEdge(0, 2);
	        g.addEdge(1, 2);
	        g.addEdge(2, 0);
	        g.addEdge(2, 3);
	        g.addEdge(3, 3);
	 
	        System.out.println("Following is Depth First Traversal "+
	                           "(starting from vertex 2)");
	 
	        g.DFS(1);

	}

}