Merge pull request aalhour#136 from yanxiaodi/xy-fix-bubbleSorter

Fix the BubbleSorter and add the unit test.

Author: aalhour

Algorithms/Sorting/BubbleSorter.cs

@@ -18,11 +18,11 @@ public static void BubbleSortAscending<T>(this IList<T> collection, Comparer<T>
         {
             for (int i = 0; i < collection.Count; i++)
             {
-                for (int index = 0; index < collection.Count - 1; index++)
+                for (int index = 0; index < collection.Count - i - 1; index++)
                 {
-                    if (comparer.Compare(collection[index], collection[index + 1])>0)
+                    if (comparer.Compare(collection[index], collection[index + 1]) > 0)
                     {
-                        collection.Swap(index,index+1);
+                        collection.Swap(index, index + 1);
                     }
                 }
             }
@@ -33,13 +33,13 @@ public static void BubbleSortAscending<T>(this IList<T> collection, Comparer<T>
         /// </summary>
         public static void BubbleSortDescending<T>(this IList<T> collection, Comparer<T> comparer)
         {
-            for (int i = 0; i < collection.Count-1; i++)
+            for (int i = 0; i < collection.Count - 1; i++)
             {
                 for (int index = 1; index < collection.Count - i; index++)
                 {
                     if (comparer.Compare(collection[index], collection[index - 1]) > 0)
                     {
-                        collection.Swap(index-1, index);
+                        collection.Swap(index - 1, index);
                     }
                 }
             }

UnitTest/AlgorithmsTests/BubbleSorterTest.cs

@@ -0,0 +1,21 @@
+using Algorithms.Sorting;
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace UnitTest.AlgorithmsTests
+{
+    public static class BubbleSorterTest
+    {
+        [Fact]
+        public static void DoTest()
+        {
+            var list = new List<int>() { 23, 42, 4, 16, 8, 15, 3, 9, 55, 0, 34, 12, 2, 46, 25 };
+            list.BubbleSort();
+            Assert.True(list.SequenceEqual(list.OrderBy(x => x)), "Wrong BubbleSort ascending");
+
+            list.BubbleSortDescending(Comparer<int>.Default);
+            Assert.True(list.SequenceEqual(list.OrderByDescending(x => x)), "Wrong BubbleSort descending");
+        }
+    }
+}