[REFACTOR] Static methods with class generics

Author: Gonzalo Diaz

src/algorithm_exercises_csharp/hackerrank/interview_preparation_kit/linked_list/lib/Node.cs

@@ -1,19 +1,15 @@
 namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.linked_list.lib;
 
-public static class LinkedList<T>
+public static class LinkedListPrinter
 {
-  public class Node(T nodeData)
-  {
-    public T data { get; set; } = nodeData;
-    public Node? next { get; set; } = null;
-  }
-
-  public static void printSinglyLinkedList(Node? node, string sep, TextWriter textWriter)
+  public static void printSinglyLinkedList<T>(LinkedList<T>.Node? node, string sep, TextWriter textWriter)
   {
-    Node? pointTo = node;
+    var pointTo = node;
 
     while (pointTo != null)
     {
+      ArgumentNullException.ThrowIfNull(textWriter);
+
       textWriter.Write(pointTo.data);
 
       pointTo = pointTo.next;
@@ -25,3 +21,12 @@ public static void printSinglyLinkedList(Node? node, string sep, TextWriter text
     }
   }
 }
+
+public static class LinkedList<T>
+{
+  public class Node(T nodeData)
+  {
+    public T data { get; set; } = nodeData;
+    public Node? next { get; set; } = default!;
+  }
+}

src/algorithm_exercises_csharp_test/hackerrank/interview_preparation_kit/linked_list/lib/Node.Test.cs

@@ -46,7 +46,7 @@ public void testPrintLinkedList()
     foreach (NodeTestCase test in tests)
     {
       using StringWriter sw = new();
-      LinkedList<int>.printSinglyLinkedList(test.llist, test.separator, sw);
+      LinkedListPrinter.printSinglyLinkedList(test.llist, test.separator, sw);
 
       string result = sw.ToString();
       Assert.AreEqual(