Initial data commit

Task/Sorting-algorithms-Heapsort/C-sharp/sorting-algorithms-heapsort.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+public class HeapSortClass
+{
+    public static void HeapSort<T>(T[] array)
+    {
+        HeapSort<T>(array, 0, array.Length, Comparer<T>.Default);
+    }
+
+    public static void HeapSort<T>(T[] array, int offset, int length, IComparer<T> comparer)
+    {
+        HeapSort<T>(array, offset, length, comparer.Compare);
+    }
+
+    public static void HeapSort<T>(T[] array, int offset, int length, Comparison<T> comparison)
+    {
+        // build binary heap from all items
+        for (int i = 0; i < length; i++)
+        {
+            int index = i;
+            T item = array[offset + i]; // use next item
+
+            // and move it on top, if greater than parent
+            while (index > 0 &&
+                comparison(array[offset + (index - 1) / 2], item) < 0)
+            {
+                int top = (index - 1) / 2;
+                array[offset + index] = array[offset + top];
+                index = top;
+            }
+            array[offset + index] = item;
+        }
+
+        for (int i = length - 1; i > 0; i--)
+        {
+            // delete max and place it as last
+            T last = array[offset + i];
+            array[offset + i] = array[offset];
+
+            int index = 0;
+            // the last one positioned in the heap
+            while (index * 2 + 1 < i)
+            {
+                int left = index * 2 + 1, right = left + 1;
+
+                if (right < i && comparison(array[offset + left], array[offset + right]) < 0)
+                {
+                    if (comparison(last, array[offset + right]) > 0) break;
+
+                    array[offset + index] = array[offset + right];
+                    index = right;
+                }
+                else
+                {
+                    if (comparison(last, array[offset + left]) > 0) break;
+
+                    array[offset + index] = array[offset + left];
+                    index = left;
+                }
+            }
+            array[offset + index] = last;
+        }
+    }
+
+    static void Main()
+    {
+        // usage
+        byte[] r = {5, 4, 1, 2};
+        HeapSort(r);
+
+        string[] s = { "-", "D", "a", "33" };
+        HeapSort(s, 0, s.Length, StringComparer.CurrentCultureIgnoreCase);
+    }
+}