1+ /*
2+ If there was a cycle, like if there was a path from one
3+ vertex to itself, we would be stuck in an infinite loop, continuously
4+ iterating over the same neighbors. To account for this, we can use an
5+ ArrayList to keep track of all the vertices that we have visited.
6+ */
7+ 8+ // USE GRAPH FILE FROM GRAPH FOLDER
9+ 10+ import java .util .ArrayList ;
11+ 12+ class GraphTraverser {
13+ public static void depthFirstTraversal (Vertex start , ArrayList <Vertex > visitedVertices ) {
14+ System .out .println (start .getData ());
15+ 16+ if (start .getEdges ().size () > 0 ) {
17+ Vertex neighbor = start .getEdges ().get (0 ).getEnd ();
18+ 19+ if (!visitedVertices .contains (neighbor )) {
20+ visitedVertices .add (neighbor );
21+ GraphTraverser .depthFirstTraversal (neighbor , visitedVertices );
22+ }
23+ }
24+ }
25+ 26+ // USE TO TEST THE GRAPH
27+ class TestGraph {
28+ private Graph testGraph ;
29+ 30+ public TestGraph () {
31+ this .testGraph = new Graph (false , true );
32+ Vertex startNode = testGraph .addVertex ("v0.0.0" );
33+ Vertex v1 = this .testGraph .addVertex ("v1.0.0" );
34+ Vertex v2 = this .testGraph .addVertex ("v2.0.0" );
35+ 36+ Vertex v11 = this .testGraph .addVertex ("v1.1.0" );
37+ Vertex v12 = this .testGraph .addVertex ("v1.2.0" );
38+ Vertex v21 = this .testGraph .addVertex ("v2.1.0" );
39+ 40+ Vertex v111 = this .testGraph .addVertex ("v1.1.1" );
41+ Vertex v112 = this .testGraph .addVertex ("v1.1.2" );
42+ Vertex v121 = this .testGraph .addVertex ("v1.2.1" );
43+ Vertex v211 = this .testGraph .addVertex ("v2.1.1" );
44+ 45+ this .testGraph .addEdge (startNode , v1 , null );
46+ this .testGraph .addEdge (startNode , v2 , null );
47+ 48+ this .testGraph .addEdge (v1 , v11 , null );
49+ this .testGraph .addEdge (v1 , v12 , null );
50+ this .testGraph .addEdge (v2 , v21 , null );
51+ 52+ this .testGraph .addEdge (v11 , v111 , null );
53+ this .testGraph .addEdge (v11 , v112 , null );
54+ this .testGraph .addEdge (v12 , v121 , null );
55+ this .testGraph .addEdge (v21 , v211 , null );
56+ 57+ // create a cycle
58+ this .testGraph .addEdge (v211 , v2 , null );
59+ }
60+ 61+ public Vertex getStartingVertex () {
62+ return this .testGraph .getVertices ().get (0 );
63+ }
64+ }
65+ 66+ // MAIN METHOD
67+ public static void main (String [] args ) {
68+ TestGraph test = new TestGraph ();
69+ Vertex startingVertex = test .getStartingVertex ();
70+ ArrayList <Vertex > visitedVertices = new ArrayList <Vertex >();
71+ visitedVertices .add (startingVertex );
72+ 73+ GraphTraverser .depthFirstTraversal (startingVertex , visitedVertices );
74+ }
75+ }
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