Merge pull request #118 from kdimolikas/development

Fix bug #89

Author: aalhour

DataStructures/Lists/DLinkedList.cs

@@ -731,19 +731,25 @@ public virtual void SelectionSort()
             var currentNode = _firstNode;
             while (currentNode != null)
             {
+                var minNode = currentNode;
                 var nextNode = currentNode.Next;
                 while (nextNode != null)
                 {
-                    if (nextNode.Data.IsLessThan(currentNode.Data))
+                    if (nextNode.Data.IsLessThan(minNode.Data))
                     {
-                        var temp = nextNode.Data;
-                        nextNode.Data = currentNode.Data;
-                        currentNode.Data = temp;
+                        minNode = nextNode;
                     }
 
                     nextNode = nextNode.Next;
                 }
 
+                if (minNode != currentNode)
+                {
+                    var temp = minNode.Data;
+                    minNode.Data = currentNode.Data;
+                    currentNode.Data = temp;
+                }
+
                 currentNode = currentNode.Next;
             }
         }

UnitTest/DataStructuresTests/DLinkedListTest.cs

@@ -95,6 +95,36 @@ public static void DoTest()
             var intArray = listOfNumbers.ToArray();
             Assert.True(intArray[0] == 0 && intArray[intArray.Length - 1] == 55, "Wrong sorting!");
         }
+
+        /// <summary>
+        ///Check SelectionSort method
+        ///</summary>
+        ///<returns></returns>
+        [Fact]
+        public static void TestSelectionSort()
+        {
+            var listOfNumbers = new DLinkedList<int>();
+            listOfNumbers.Append(23);
+            listOfNumbers.Append(42);
+            listOfNumbers.Append(4);
+            listOfNumbers.Append(16);
+            listOfNumbers.Append(8);
+            listOfNumbers.Append(15);
+            listOfNumbers.Append(9);
+            listOfNumbers.Append(55);
+            listOfNumbers.Append(0);
+
+            listOfNumbers.SelectionSort();
+            var intArray = listOfNumbers.ToArray();
+            var i = 0;
+            while (i < intArray.Length - 1)
+            {
+                Assert.True(intArray[i] <= intArray[i + 1], "Wrong sorting at index: " + i);
+                ++i;
+            }
+
+        }
+
     }
 }