[BUGFIX] sonarcloud (Maintainability) Add a 'protected' constructor or the 'static' keyword to the class declaration.

Utility classes should not have public constructors csharpsquid:S1118

Author: Gonzalo Diaz

src/algorithm_exercises_csharp/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/CountTriplets.cs

@@ -4,10 +4,14 @@
 
 namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.dictionaries_and_hashmaps;
 
+using System.Diagnostics.CodeAnalysis;
 using System.Collections.Generic;
 
 public class CountTriplets
 {
+  [ExcludeFromCodeCoverage]
+  protected CountTriplets() { }
+
   public static long countTriplets(List<long> arr, long r)
   {
     Dictionary<long, long> aCounter = [];

src/algorithm_exercises_csharp/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/CountTripletsBruteForce.cs

@@ -7,6 +7,9 @@ namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.dictio
 
 public class CountTripletsBruteForce
 {
+  [ExcludeFromCodeCoverage]
+  protected CountTripletsBruteForce() { }
+
   public static long countTriplets(List<long> arr, long r)
   {
     long size = arr.Count;

src/algorithm_exercises_csharp/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/RansomNote.cs

@@ -7,6 +7,9 @@ namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.dictio
 
 public class RansomNote
 {
+  [ExcludeFromCodeCoverage]
+  protected RansomNote() { }
+
   public class InvalidValueException : Exception
   {
     // constructor for the InvalidAgeException class
@@ -16,9 +19,6 @@ public InvalidValueException(string msg)
     }
   }
 
-  [ExcludeFromCodeCoverage]
-  protected RansomNote() { }
-
   private static readonly string __YES__ = "Yes";
   private static readonly string __NO__ = "No";