refactor: adding classificationRatio as parameter

Author: Alex Klymenko

src/main/java/com/thealgorithms/sorts/FlashSort.java

@@ -22,7 +22,22 @@
  * </ol>
  */
 public class FlashSort implements SortAlgorithm {
-    private static final double CLASSIFICATION_RATIO = 0.45;
+    private final double classificationRatio;
+
+    public FlashSort() {
+        classificationRatio = 0.45;
+    }
+
+    public FlashSort(double classificationRatio) {
+        if (classificationRatio <= 0 || classificationRatio >= 1) {
+            throw new IllegalArgumentException("Classification ratio must be between 0 and 1 (exclusive).");
+        }
+        this.classificationRatio = classificationRatio;
+    }
+
+    public double getClassificationRatio() {
+        return classificationRatio;
+    }
 
     /**
      * Sorts an array using the Flash Sort algorithm.
@@ -55,7 +70,7 @@ private <T extends Comparable<? super T>> void flashSort(T[] arr) {
             return; // All elements are the same
         }
 
-        final int m = (int) (CLASSIFICATION_RATIO * arr.length);
+        final int m = (int) (classificationRatio * arr.length);
 
         final int[] classificationArray = new int[m];
 

src/test/java/com/thealgorithms/sorts/FlashSortTest.java

@@ -1,8 +1,35 @@
 package com.thealgorithms.sorts;
 
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
 public class FlashSortTest extends SortingAlgorithmTest {
     @Override
     SortAlgorithm getSortAlgorithm() {
         return new FlashSort();
     }
+
+    @Test
+    public void testDefaultConstructor() {
+        double defaultRation = 0.45;
+        FlashSort sorter = new FlashSort();
+        assertEquals(defaultRation, sorter.getClassificationRatio());
+    }
+
+    @ParameterizedTest
+    @ValueSource(doubles = {0.1, 0.2, 0.5, 0.9})
+    public void testCustomConstructorValidRatio(double ratio) {
+        FlashSort sorter = new FlashSort(ratio);
+        assertEquals(ratio, sorter.getClassificationRatio());
+    }
+
+    @ParameterizedTest
+    @ValueSource(doubles = {0, 1, -0.1, 1.1})
+    public void testCustomConstructorInvalidRatio(double ratio) {
+        assertThrows(IllegalArgumentException.class, () -> new FlashSort(ratio));
+    }
 }