Create BFS.java

BFS.java

@@ -0,0 +1,96 @@
+package com.test.graph.algo;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Queue;
+import java.util.Stack;
+import java.util.concurrent.ArrayBlockingQueue;
+
+
+public class BFS {
+
+	private Graph.Vertex edgeTo[];
+
+	public BFS(int size) {
+		edgeTo = new Graph.Vertex[size];
+	}
+
+	public void bfs(Graph g, Graph.Vertex q){
+
+		Queue<Graph.Vertex> queue = new ArrayBlockingQueue<Graph.Vertex>(g.getVertices().size());
+		q.visited = true;
+		System.out.println("Vertex : "+q);
+		queue.add(q);
+		Graph.Vertex w,v;
+		while (!queue.isEmpty()) {
+			v = queue.remove();
+			while ( (w = getAdjUnvisitedVertex(v)) != null) {
+				w.visited = true;
+				queue.add(w);
+				edgeTo[g.getIndexOf(w)] = v; // creating paths from v
+				System.out.println("Vertex : "+w);
+			}
+		}
+	}
+
+	public Graph.Vertex getAdjUnvisitedVertex(Graph.Vertex v){
+		for (Graph.Edge e : v.getEdges()) {
+			if (!e.getTo().visited){
+				return e.getTo();
+			}
+		}
+		return null;
+	}
+
+	public void printPath(Graph g, Graph.Vertex source, Graph.Vertex target){
+
+		Stack<Graph.Vertex> path = new Stack<Graph.Vertex>();
+		for (Graph.Vertex v = target; v != source ; v = edgeTo[g.getIndexOf(v)]){
+			path.add(v);
+		}
+		path.add(source);
+		System.out.print("Path");
+		while (!path.isEmpty()) {
+			System.out.print("--"+path.pop());
+		}
+	}
+
+
+	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);
+
+		BFS bfsObj = new BFS(g.getVertices().size());
+		bfsObj.bfs(g, A);
+		bfsObj.printPath(g, B, G);
+	}
+
+}