Added Breadth First Traversal (All Layers)

Author: indraantoor

Graph Data Structures/Graph Traversal/Breadth-First Traversal/Breadth-First Traversal (All layers)/GraphTraverser.java

@@ -0,0 +1,127 @@
+// USE GRAPH FILE FROM GRAPH FOLDER
+
+import java.util.ArrayList;
+
+class GraphTraverser {
+    // QUEUE
+    public class Queue {
+
+        public LinkedList queue;
+        public int size;
+
+        public Queue() {
+            this.queue = new LinkedList();
+            this.size = 0;
+        }
+
+        public boolean isEmpty() {
+            return this.size == 0;
+        }
+
+        public void enqueue(Vertex data) {
+            this.queue.addToTail(data);
+            this.size++;
+        }
+
+        public Vertex peek() {
+            if (this.isEmpty()) {
+                return null;
+            } else {
+                return this.queue.head.data;
+            }
+        }
+
+        public Vertex dequeue() {
+            if (!this.isEmpty()) {
+                Vertex data = this.queue.removeHead();
+                this.size--;
+                return data;
+            } else {
+                throw new Error("LinearDataStructures.Queues.Queue is empty!");
+            }
+        }
+
+    }
+
+    // GRAPH TRAVERSER
+    public static void depthFirstTraversal(Vertex start, ArrayList<Vertex> visitedVertices) {
+        System.out.println(start.getData());
+
+        for (Edge e: start.getEdges()) {
+            Vertex neighbor = e.getEnd();
+
+            if (!visitedVertices.contains(neighbor)) {
+                visitedVertices.add(neighbor);
+                GraphTraverser.depthFirstTraversal(neighbor, visitedVertices);
+            }
+        }
+    }
+
+    public static void breadthFirstTraversal(Vertex start, ArrayList<Vertex> visitedVertices) {
+        Queue visitQueue = new Queue();
+        visitQueue.enqueue(start);
+
+        while (!visitQueue.isEmpty()) {
+            Vertex current = visitQueue.dequeue();
+            System.out.println(current.getData());
+
+            for(Edge e : current.getEdges()) {
+                Vertex neighbor = e.getEnd();
+                if(!visitedVertices.contains(neighbor)) {
+                    visitQueue.enqueue(neighbor);
+                    visitedVertices.add(neighbor);
+                }
+            }
+        }
+    }
+
+    // USE IT TO TEST GRAPH
+    class TestGraph {
+        private Graph testGraph;
+
+        public TestGraph() {
+            this.testGraph = new Graph(false, true);
+            Vertex startNode = testGraph.addVertex("v0.0.0");
+            Vertex v1 = this.testGraph.addVertex("v1.0.0");
+            Vertex v2 = this.testGraph.addVertex("v2.0.0");
+
+            Vertex v11 = this.testGraph.addVertex("v1.1.0");
+            Vertex v12 = this.testGraph.addVertex("v1.2.0");
+            Vertex v21 = this.testGraph.addVertex("v2.1.0");
+
+            Vertex v111 = this.testGraph.addVertex("v1.1.1");
+            Vertex v112 = this.testGraph.addVertex("v1.1.2");
+            Vertex v121 = this.testGraph.addVertex("v1.2.1");
+            Vertex v211 = this.testGraph.addVertex("v2.1.1");
+
+            this.testGraph.addEdge(startNode, v1, null);
+            this.testGraph.addEdge(startNode, v2, null);
+
+            this.testGraph.addEdge(v1, v11, null);
+            this.testGraph.addEdge(v1, v12, null);
+            this.testGraph.addEdge(v2, v21, null);
+
+            this.testGraph.addEdge(v11, v111, null);
+            this.testGraph.addEdge(v11, v112, null);
+            this.testGraph.addEdge(v12, v121, null);
+            this.testGraph.addEdge(v21, v211, null);
+
+            // create a cycle
+            this.testGraph.addEdge(v211, v2, null);
+        }
+
+        public Vertex getStartingVertex() {
+            return this.testGraph.getVertices().get(0);
+        }
+    }
+
+    // MAIN METHOD
+    public static void main(String[] args) {
+        TestGraph test = new TestGraph();
+        Vertex startingVertex = test.getStartingVertex();
+        ArrayList<Vertex> visitedVertices = new ArrayList<Vertex>();
+        visitedVertices.add(startingVertex);
+
+        GraphTraverser.breadthFirstTraversal(startingVertex, visitedVertices);
+    }
+}}