[REFACTOR] File may only contain a single type. (SA1402)

Author: Gonzalo Diaz

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

@@ -0,0 +1,21 @@
+namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.linked_list.lib;
+
+public static class LinkedListPrinter
+{
+  public static void printSinglyLinkedList<T>(LinkedList<T>.Node? node, string sep, TextWriter textWriter)
+  {
+    var pointTo = node;
+
+    while (pointTo != null)
+    {
+      textWriter.Write(pointTo.data);
+
+      pointTo = pointTo.next;
+
+      if (pointTo != null)
+      {
+        textWriter.Write(sep);
+      }
+    }
+  }
+}

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

@@ -1,27 +1,10 @@
 namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.linked_list.lib;
 
-public class LinkedList<T>
+public static class LinkedList<T>
 {
   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)
-  {
-    Node? pointTo = node;
-
-    while (pointTo != null)
-    {
-      textWriter.Write(pointTo.data);
-
-      pointTo = pointTo.next;
-
-      if (pointTo != null)
-      {
-        textWriter.Write(sep);
-      }
-    }
+    public Node? next { get; set; } = default!;
   }
 }

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

@@ -4,7 +4,7 @@ namespace algorithm_exercises_csharp_test.hackerrank.interview_preparation_kit.l
 [TestClass]
 public class NodeTest
 {
-  class NodeTestCase
+  private sealed class NodeTestCase
   {
     public string title = "";
     public LinkedList<int>.Node? llist;
@@ -45,15 +45,15 @@ public void testPrintLinkedList()
   {
     foreach (NodeTestCase test in tests)
     {
-      StringWriter sw = new();
-
-      LinkedList<int>.printSinglyLinkedList(test.llist, test.separator, sw);
+      using StringWriter sw = new();
+      LinkedListPrinter.printSinglyLinkedList<int>(test.llist, test.separator, sw);
 
       string result = sw.ToString();
       Assert.AreEqual(
         test.expected,
         result,
-        String.Format(
+        string.Format(
+          System.Globalization.CultureInfo.InvariantCulture,
           "{0} testPrintLinkedList<int>(<Node>, {1}, <Textwriter>) => must be: {2}",
           test.title,
           test.separator,