From 0229c16365e5d849857b30ef6bd6634f89913a4b Mon Sep 17 00:00:00 2001
From: Stefan Suhren <suhren.stefan@fh-swf.de>
Date: Thu, 20 Nov 2014 18:39:54 +0100
Subject: Assignment No.8 implemented non recursive FaB

---
 .../in/inf/java1/aufgabe8/FloydAndBentley.java     | 218 ++++++++++++---------
 1 file changed, 130 insertions(+), 88 deletions(-)

(limited to 'src/de/fhswf/in/inf/java1/aufgabe8/FloydAndBentley.java')

diff --git a/src/de/fhswf/in/inf/java1/aufgabe8/FloydAndBentley.java b/src/de/fhswf/in/inf/java1/aufgabe8/FloydAndBentley.java
index 8ec8464..54dd863 100644
--- a/src/de/fhswf/in/inf/java1/aufgabe8/FloydAndBentley.java
+++ b/src/de/fhswf/in/inf/java1/aufgabe8/FloydAndBentley.java
@@ -1,88 +1,130 @@
-/**
- * 
- */
-package de.fhswf.in.inf.java1.aufgabe8;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Random;
-
-/**
- * TODO Add comment here
- *
- * @author $Author: $
- * @version $Revision: $, $Date: $ UTC
- */
-public final class FloydAndBentley
-{
-
-   private static Random rnd = new Random();
-
-   /**
-    * TODO Add constructor comment here
-    *
-    */
-   private FloydAndBentley()
-   {
-      // TODO Auto-generated constructor stub
-   }
-
-   /**
-    * A function which chooses a sample from a List with the Floyd and Bentley
-    * algorithm.
-    *
-    *
-    * @param <T>
-    *           Type of the Lists.
-    * @param s
-    *           The set from which the sample is chosen.
-    * @param k
-    *           The number of items to be chosen.
-    * @return Return the ordered sample.
-    */
-   public static <T> List<T> sample(List<T> s, int k)
-   {
-      if (s.isEmpty())
-      {
-         throw new IllegalArgumentException("Set is empty");
-      }
-      if (k > s.size())
-      {
-         throw new IllegalArgumentException("k is bigger than the Set");
-      }
-
-      List<T> ret = new ArrayList<>(k);
-      sampleRec(s, k, ret);
-
-      return ret;
-
-   }
-
-   /**
-    * TODO Add method comment here
-    *
-    * @param <T>
-    * @param s
-    * @param k
-    * @param ret
-    */
-   private static <T> void sampleRec(List<T> s, int k, List<T> ret)
-   {
-      if (ret.size() >= k)
-      {
-         return;
-      }
-
-      T val = s.get(rnd.nextInt(s.size() - ((k - ret.size()) - 1)));
-
-      if (ret.contains(val))
-      {
-         val = s.get(s.size() - ((k - ret.size()) - 1));
-      }
-
-      ret.add(val);
-
-      sampleRec(s, k, ret);
-
-   }
-}
+/**
+ * 
+ */
+package de.fhswf.in.inf.java1.aufgabe8;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+/**
+ * Utility class for the Floyd and Bentley algorithm.
+ *
+ * @author $Author: $
+ * @version $Revision: $, $Date: $ UTC
+ */
+public final class FloydAndBentley
+{
+
+   private static Random rnd = new Random();
+
+   /**
+    * Private constructor for utility class.
+    *
+    */
+   private FloydAndBentley()
+   {
+   }
+
+   /**
+    * A function which chooses a sample from a List with the Floyd and Bentley
+    * algorithm. (Recursive algorithm)
+    *
+    * @param <T>
+    *           Type of the Lists.
+    * @param s
+    *           The set from which the sample is chosen.
+    * @param k
+    *           The number of items to be chosen.
+    * @return Return the sample.
+    */
+   public static <T> List<T> sample(List<T> s, int k)
+   {
+      if (s.isEmpty())
+      {
+         throw new IllegalArgumentException("Set is empty");
+      }
+      if (k > s.size())
+      {
+         throw new IllegalArgumentException("k is bigger than the Set");
+      }
+
+      List<T> ret = new ArrayList<>(k);
+      sampleRec(s, k, ret);
+
+      return ret;
+
+   }
+
+   /**
+    * The recursive implementation of the Floyd and Bentley algorithm.
+    *
+    * @param <T>
+    *           Type of the Lists.
+    * @param s
+    *           The set from which the sample is chosen.
+    * @param k
+    *           The number of items to be chosen.
+    * @param ret
+    *           Return the sample.
+    */
+   private static <T> void sampleRec(List<T> s, int k, List<T> ret)
+   {
+      if (ret.size() >= k)
+      {
+         return;
+      }
+
+      T val = s.get(rnd.nextInt(s.size() - (k - ret.size())));
+
+      if (ret.contains(val))
+      {
+         val = s.get(s.size() - (k - ret.size()));
+      }
+
+      ret.add(val);
+
+      sampleRec(s, k, ret);
+
+   }
+
+   /**
+    * A function which chooses a sample from a List with the Floyd and Bentley
+    * algorithm. (Non recursive algorithm)
+    *
+    * @param <T>
+    *           Type of the Lists.
+    * @param s
+    *           The set from which the sample is chosen.
+    * @param k
+    *           The number of items to be chosen.
+    * @return Return the sample.
+    */
+   public static <T> List<T> sample2(List<T> s, int k)
+   {
+      if (s.isEmpty())
+      {
+         throw new IllegalArgumentException("Set is empty");
+      }
+      if (k > s.size())
+      {
+         throw new IllegalArgumentException("k is bigger than the Set");
+      }
+
+      List<T> ret = new ArrayList<>(k);
+
+      for (int i = 0; i < k; i++)
+      {
+         T val = s.get(rnd.nextInt(s.size() - (k - ret.size())));
+
+         if (ret.contains(val))
+         {
+            val = s.get(s.size() - (k - ret.size()));
+         }
+
+         ret.add(val);
+      }
+
+      return ret;
+   }
+}
-- 
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