Create DFS.java

DFS.java

@@ -0,0 +1,103 @@
+package com.test.graph.algo;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Stack;
+/*
+ * @author rrohit
+ */
+public class DFS {
+	private static boolean [] visited;
+	private static int count;
+
+	/*
+	 * Without recursion approach
+	 */
+	public static void dfs(Graph g){
+
+		visited = new boolean[g.getVertices().size()];
+		Stack<Graph.Vertex> stack = new Stack<Graph.Vertex>();
+
+		if (g.getVertices().size() == 0){
+			System.out.println("Graph Is Empty :: Return");
+			return;
+		}
+
+		visited[0] = true;
+		stack.add(g.getVertices().get(0));
+		System.out.println("Vertex Visited: "+stack.peek()); // similar to stack.top()
+		Graph.Vertex v,w;
+		while(!stack.isEmpty()){
+			count++;
+			v = stack.peek();
+			if ( (w = getAdjUnvisitedVertex(v, g)) != null){
+				stack.add(w);
+				visited[g.getVertices().indexOf(w)] = true;
+				System.out.println("Vertex Visited: "+w);
+			}else {
+				stack.pop();
+			}
+		}
+		System.out.println("Total Count = "+count);
+	}
+
+	public static Graph.Vertex getAdjUnvisitedVertex(Graph.Vertex v, Graph g){
+
+		for (Graph.Edge e : v.getEdges()) {
+			count++;
+			if (e.getFrom().equals(v) && !visited[g.getVertices().indexOf(e.getTo())]){
+				return e.getTo();
+			}
+		}
+		return null;
+	}
+
+	public static void dfsRecurssive(Graph g, Graph.Vertex v){
+		System.out.println("Visited : "+v);
+		v.visited = true;
+
+		for (Graph.Edge e : v.getEdges()) {
+			Graph.Vertex w = e.getTo();
+			if (!w.visited){
+				dfsRecurssive(g,w);
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+
+		List<Graph.Vertex> vertices = new ArrayList<Graph.Vertex>(); 
+		Graph.Vertex A = new Graph.Vertex('A');
+		Graph.Vertex B = new Graph.Vertex('B');
+		Graph.Vertex C = new Graph.Vertex('C');
+		Graph.Vertex D = new Graph.Vertex('D');
+		Graph.Vertex E = new Graph.Vertex('E');
+		Graph.Vertex F = new Graph.Vertex('F');
+		Graph.Vertex G = new Graph.Vertex('G');
+		Graph.Vertex H = new Graph.Vertex('H');
+		vertices.add(A);
+		vertices.add(B);
+		vertices.add(C);
+		vertices.add(D);
+		vertices.add(E);
+		vertices.add(F);
+		vertices.add(G);
+		vertices.add(H);
+
+		List<Graph.Edge> edges = new ArrayList<Graph.Edge>();
+		edges.add(new Graph.Edge(0,A,B));
+		edges.add(new Graph.Edge(0,B,C));
+		edges.add(new Graph.Edge(0,B,H));
+		edges.add(new Graph.Edge(0,C,D));
+		edges.add(new Graph.Edge(0,C,E));
+		edges.add(new Graph.Edge(0,E,H));
+		edges.add(new Graph.Edge(0,E,F));
+		edges.add(new Graph.Edge(0,E,G));
+
+		Graph g = new Graph(vertices, edges);
+		dfs(g);
+		dfsRecurssive(g, A);
+	}
+}
+
+