Changed cycle detection to be generic

Author: Justin Wetherell

src/com/jwetherell/algorithms/graph/CycleDetection.java

@@ -21,40 +21,40 @@ private CycleDetection() { }
      * @param graph Graph
      * @return true if a cycle exists
      */
-    public static boolean detect(Graph<Integer> graph) {
+    public static <T extends Comparable<T>> boolean detect(Graph<T> graph) {
         if (graph == null)
             throw new IllegalArgumentException("Graph is NULL.");
 
         if (graph.getType() != Graph.TYPE.UNDIRECTED)
             throw new IllegalArgumentException("Graph is needs to be Undirected.");
 
-        final Set<Graph.Vertex<Integer>> visitedVerticies = new HashSet<Graph.Vertex<Integer>>();
-        final Set<Graph.Edge<Integer>> visitedEdges = new HashSet<Graph.Edge<Integer>>();
+        final Set<Graph.Vertex<T>> visitedVerticies = new HashSet<Graph.Vertex<T>>();
+        final Set<Graph.Edge<T>> visitedEdges = new HashSet<Graph.Edge<T>>();
 
-        final List<Graph.Vertex<Integer>> verticies = graph.getVertices();
+        final List<Graph.Vertex<T>> verticies = graph.getVertices();
         if (verticies == null || verticies.size() == 0)
             return false;
 
         // Select the zero-ith element as the root
-        final Graph.Vertex<Integer> root = verticies.get(0);
+        final Graph.Vertex<T> root = verticies.get(0);
         return depthFirstSearch(root, visitedVerticies, visitedEdges);
     }
 
-    private static final boolean depthFirstSearch(Graph.Vertex<Integer> vertex, Set<Graph.Vertex<Integer>> visitedVerticies, Set<Graph.Edge<Integer>> visitedEdges) {
+    private static final <T extends Comparable<T>> boolean depthFirstSearch(Graph.Vertex<T> vertex, Set<Graph.Vertex<T>> visitedVerticies, Set<Graph.Edge<T>> visitedEdges) {
         if (!visitedVerticies.contains(vertex)) {
             // Found an unvisited, add to the set
             visitedVerticies.add(vertex);
 
-            final List<Graph.Edge<Integer>> edges = vertex.getEdges();
+            final List<Graph.Edge<T>> edges = vertex.getEdges();
             if (edges != null) {
                 // Follow each unvisited edge, visit the vertex the edge connects to.
-                for (Graph.Edge<Integer> edge : edges) {
-                    final Graph.Vertex<Integer> to = edge.getToVertex();
+                for (Graph.Edge<T> edge : edges) {
+                    final Graph.Vertex<T> to = edge.getToVertex();
                     boolean result = false;
                     if (to != null && !visitedEdges.contains(edge)) {
                         visitedEdges.add(edge);
 
-                        final Graph.Edge<Integer> recip = new Graph.Edge<Integer>(edge.getCost(), edge.getToVertex(), edge.getFromVertex());
+                        final Graph.Edge<T> recip = new Graph.Edge<T>(edge.getCost(), edge.getToVertex(), edge.getFromVertex());
                         visitedEdges.add(recip);
 
                         result = depthFirstSearch(to, visitedVerticies, visitedEdges);