checks fixes

Author: varada610

src/main/java/com/thealgorithms/matrix/MirrorOfMatrix.java

@@ -20,7 +20,7 @@ public final class MirrorOfMatrix {
     private MirrorOfMatrix() {
     }
 
-    public static double[][] mirrorMatrix(final double[][] originalMatrix) {       
+    public static double[][] mirrorMatrix(final double[][] originalMatrix) {
         MatrixUtil.validateInputMatrix(originalMatrix);
 
         int numRows = originalMatrix.length;
@@ -32,5 +32,5 @@ public static double[][] mirrorMatrix(final double[][] originalMatrix) {
             mirroredMatrix[i] = MatrixUtil.reverseRow(originalMatrix[i]);
         }
         return mirroredMatrix;
-    }  
+    }
 }

src/main/java/com/thealgorithms/matrix/utils/MatrixUtil.java

@@ -11,6 +11,9 @@
  */
 public class MatrixUtil {
 
+    private MatrixUtil() {
+    }
+
     private static boolean isValid(final BigDecimal[][] matrix) {
         return matrix != null && matrix.length > 0 && matrix[0].length > 0;
     }

src/main/java/com/thealgorithms/puzzlesandgames/Sudoku.java

@@ -9,6 +9,9 @@
  */
 final class Sudoku {
 
+    private Sudoku() {
+    }
+
     /**
      * Checks if placing a number in a specific position on the Sudoku board is safe.
      * The number is considered safe if it does not violate any of the Sudoku rules:

src/main/java/com/thealgorithms/puzzlesandgames/TowerOfHanoi.java

@@ -23,7 +23,7 @@
  * Space Complexity: O(n) - Linear space complexity due to the recursion stack.
  * Wikipedia: https://en.wikipedia.org/wiki/Tower_of_Hanoi
  */
-class TowerOfHanoi {
+final class TowerOfHanoi {
 
     private TowerOfHanoi() {
     }

src/main/java/com/thealgorithms/puzzlesandgames/WordBoggle.java

@@ -9,6 +9,8 @@
 
 public final class WordBoggle {
 
+    private WordBoggle() {
+    }
     /**
      * O(nm * 8^s + ws) time where n = width of boggle board, m = height of
      * boggle board, s = length of longest word in string array, w = length of