Merge branch 'master' into improvement/improved-gcd-class

Author: siriak

DIRECTORY.md

@@ -982,6 +982,7 @@
             * [JosephusProblemTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/JosephusProblemTest.java)
             * [KaprekarNumbersTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java)
             * [KaratsubaMultiplicationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/KaratsubaMultiplicationTest.java)
+            * [KrishnamurthyNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/KrishnamurthyNumberTest.java)
             * [LeastCommonMultipleTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LeastCommonMultipleTest.java)
             * [LeonardoNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LeonardoNumberTest.java)
             * [LiouvilleLambdaFunctionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LiouvilleLambdaFunctionTest.java)

src/main/java/com/thealgorithms/dynamicprogramming/RodCutting.java

@@ -22,6 +22,10 @@ public static int cutRod(int[] price, int n) {
         if (price == null || price.length == 0) {
             throw new IllegalArgumentException("Price array cannot be null or empty.");
         }
+        if (n < 0) {
+            throw new IllegalArgumentException("Rod length cannot be negative.");
+        }
+
         // Create an array to store the maximum obtainable values for each rod length.
         int[] val = new int[n + 1];
         val[0] = 0;

src/main/java/com/thealgorithms/maths/KrishnamurthyNumber.java

@@ -1,31 +1,38 @@
 package com.thealgorithms.maths;
 
-/* This is a program to check if a number is a Krishnamurthy number or not.
-A number is a Krishnamurthy number if the sum of the factorials of the digits of the number is equal
-to the number itself. For example, 1, 2 and 145 are Krishnamurthy numbers. Krishnamurthy number is
-also referred to as a Strong number.
+/**
+ * Utility class for checking if a number is a Krishnamurthy number.
+ *
+ * A Krishnamurthy number (also known as a Strong number) is a number whose sum of the factorials of its digits is equal to the number itself.
+ *
+ * For example, 145 is a Krishnamurthy number because 1! + 4! + 5! = 1 + 24 + 120 = 145.
+ * <b>Example usage:</b>
+ * <pre>
+ * boolean isKrishnamurthy = KrishnamurthyNumber.isKrishnamurthy(145);
+ * System.out.println(isKrishnamurthy); // Output: true
+ *
+ * isKrishnamurthy = KrishnamurthyNumber.isKrishnamurthy(123);
+ * System.out.println(isKrishnamurthy); // Output: false
+ * </pre>
  */
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-
 public final class KrishnamurthyNumber {
+
     private KrishnamurthyNumber() {
     }
 
-    // returns True if the number is a Krishnamurthy number and False if it is not.
-
-    public static boolean isKMurthy(int n) {
-        // initialising the variable s that will store the sum of the factorials of the digits to 0
-        int s = 0;
-        // storing the number n in a temporary variable tmp
+    /**
+     * Checks if a number is a Krishnamurthy number.
+     *
+     * @param n The number to check
+     * @return true if the number is a Krishnamurthy number, false otherwise
+     */
+    public static boolean isKrishnamurthy(int n) {
         int tmp = n;
+        int s = 0;
 
-        // Krishnamurthy numbers are positive
         if (n <= 0) {
             return false;
-        } // checking if the number is a Krishnamurthy number
-        else {
+        } else {
             while (n != 0) {
                 // initialising the variable fact that will store the factorials of the digits
                 int fact = 1;
@@ -43,15 +50,4 @@ public static boolean isKMurthy(int n) {
             return tmp == s;
         }
     }
-
-    public static void main(String[] args) throws IOException {
-        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-        System.out.println("Enter a number to check if it is a Krishnamurthy number: ");
-        int n = Integer.parseInt(br.readLine());
-        if (isKMurthy(n)) {
-            System.out.println(n + " is a Krishnamurthy number.");
-        } else {
-            System.out.println(n + " is NOT a Krishnamurthy number.");
-        }
-    }
 }

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

@@ -0,0 +1,40 @@
+package com.thealgorithms.sorts;
+
+public class AdaptiveMergeSort implements SortAlgorithm {
+    @SuppressWarnings("unchecked")
+    public <T extends Comparable<T>> T[] sort(T[] array) {
+        if (array.length <= 1) {
+            return array;
+        }
+        T[] aux = array.clone();
+        sort(array, aux, 0, array.length - 1);
+        return array;
+    }
+
+    private <T extends Comparable<T>> void sort(T[] array, T[] aux, int low, int high) {
+        if (low >= high) {
+            return;
+        }
+        int mid = low + (high - low) / 2;
+        sort(array, aux, low, mid);
+        sort(array, aux, mid + 1, high);
+        merge(array, aux, low, mid, high);
+    }
+
+    private <T extends Comparable<T>> void merge(T[] array, T[] aux, int low, int mid, int high) {
+        System.arraycopy(array, low, aux, low, high - low + 1);
+        int i = low;
+        int j = mid + 1;
+        for (int k = low; k <= high; k++) {
+            if (i > mid) {
+                array[k] = aux[j++];
+            } else if (j > high) {
+                array[k] = aux[i++];
+            } else if (aux[j].compareTo(aux[i]) < 0) {
+                array[k] = aux[j++];
+            } else {
+                array[k] = aux[i++];
+            }
+        }
+    }
+}

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

@@ -0,0 +1,21 @@
+package com.thealgorithms.sorts;
+
+public class StalinSort implements SortAlgorithm {
+    @SuppressWarnings("unchecked")
+    public <T extends Comparable<T>> T[] sort(T[] array) {
+        if (array.length == 0) {
+            return array;
+        }
+        int currentIndex = 0;
+        for (int i = 1; i < array.length; i++) {
+            if (array[i].compareTo(array[currentIndex]) >= 0) {
+                currentIndex++;
+                array[currentIndex] = array[i];
+            }
+        }
+        // Create a result array with sorted elements
+        T[] result = (T[]) java.lang.reflect.Array.newInstance(array.getClass().getComponentType(), currentIndex + 1);
+        System.arraycopy(array, 0, result, 0, currentIndex + 1);
+        return result;
+    }
+}

src/test/java/com/thealgorithms/dynamicprogramming/RodCuttingTest.java

@@ -93,4 +93,10 @@ void testCutRodEmptyPrices() {
         int length = 5;
         assertThrows(IllegalArgumentException.class, () -> RodCutting.cutRod(prices, length), "An empty prices array should throw an IllegalArgumentException.");
     }
+    @Test
+    void testCutRodNegativeLength() {
+        int[] prices = {1, 5, 8, 9, 10}; // Prices are irrelevant for negative length
+        int length = -1;
+        assertThrows(IllegalArgumentException.class, () -> RodCutting.cutRod(prices, length), "A negative rod length should throw an IllegalArgumentException.");
+    }
 }

src/test/java/com/thealgorithms/maths/KrishnamurthyNumberTest.java

@@ -0,0 +1,62 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the KrishnamurthyNumber class.
+ */
+public class KrishnamurthyNumberTest {
+
+    /**
+     * Test the isKrishnamurthy method with a known Krishnamurthy number.
+     */
+    @Test
+    public void testIsKrishnamurthyTrue() {
+        assertTrue(KrishnamurthyNumber.isKrishnamurthy(145));
+    }
+
+    /**
+     * Test the isKrishnamurthy method with a number that is not a Krishnamurthy number.
+     */
+    @Test
+    public void testIsKrishnamurthyFalse() {
+        assertFalse(KrishnamurthyNumber.isKrishnamurthy(123));
+    }
+
+    /**
+     * Test the isKrishnamurthy method with zero.
+     */
+    @Test
+    public void testIsKrishnamurthyZero() {
+        assertFalse(KrishnamurthyNumber.isKrishnamurthy(0));
+    }
+
+    /**
+     * Test the isKrishnamurthy method with a negative number.
+     */
+    @Test
+    public void testIsKrishnamurthyNegative() {
+        assertFalse(KrishnamurthyNumber.isKrishnamurthy(-145));
+    }
+
+    /**
+     * Test the isKrishnamurthy method with a single-digit Krishnamurthy number.
+     */
+    @Test
+    public void testIsKrishnamurthySingleDigitTrue() {
+        assertTrue(KrishnamurthyNumber.isKrishnamurthy(1));
+        assertTrue(KrishnamurthyNumber.isKrishnamurthy(2));
+    }
+
+    /**
+     * Test the isKrishnamurthy method with a single-digit number that is not a Krishnamurthy number.
+     */
+    @Test
+    public void testIsKrishnamurthySingleDigitFalse() {
+        assertFalse(KrishnamurthyNumber.isKrishnamurthy(3));
+        assertFalse(KrishnamurthyNumber.isKrishnamurthy(4));
+    }
+}

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

@@ -0,0 +1,53 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class AdaptiveMergeSortTest {
+
+    @Test
+    public void testSortIntegers() {
+        AdaptiveMergeSort adaptiveMergeSort = new AdaptiveMergeSort();
+        Integer[] input = {4, 23, 6, 78, 1, 54, 231, 9, 12};
+        Integer[] expected = {1, 4, 6, 9, 12, 23, 54, 78, 231};
+        Integer[] result = adaptiveMergeSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortStrings() {
+        AdaptiveMergeSort adaptiveMergeSort = new AdaptiveMergeSort();
+        String[] input = {"c", "a", "e", "b", "d"};
+        String[] expected = {"a", "b", "c", "d", "e"};
+        String[] result = adaptiveMergeSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortWithDuplicates() {
+        AdaptiveMergeSort adaptiveMergeSort = new AdaptiveMergeSort();
+        Integer[] input = {1, 3, 2, 2, 5, 4};
+        Integer[] expected = {1, 2, 2, 3, 4, 5};
+        Integer[] result = adaptiveMergeSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortEmptyArray() {
+        AdaptiveMergeSort adaptiveMergeSort = new AdaptiveMergeSort();
+        Integer[] input = {};
+        Integer[] expected = {};
+        Integer[] result = adaptiveMergeSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortSingleElement() {
+        AdaptiveMergeSort adaptiveMergeSort = new AdaptiveMergeSort();
+        Integer[] input = {42};
+        Integer[] expected = {42};
+        Integer[] result = adaptiveMergeSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+}

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

@@ -0,0 +1,53 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class StalinSortTest {
+
+    @Test
+    public void testSortIntegers() {
+        StalinSort stalinSort = new StalinSort();
+        Integer[] input = {4, 23, 6, 78, 1, 54, 231, 9, 12};
+        Integer[] expected = {4, 23, 78, 231};
+        Integer[] result = stalinSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortStrings() {
+        StalinSort stalinSort = new StalinSort();
+        String[] input = {"c", "a", "e", "b", "d"};
+        String[] expected = {"c", "e"};
+        String[] result = stalinSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortWithDuplicates() {
+        StalinSort stalinSort = new StalinSort();
+        Integer[] input = {1, 3, 2, 2, 5, 4};
+        Integer[] expected = {1, 3, 5};
+        Integer[] result = stalinSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortEmptyArray() {
+        StalinSort stalinSort = new StalinSort();
+        Integer[] input = {};
+        Integer[] expected = {};
+        Integer[] result = stalinSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testSortSingleElement() {
+        StalinSort stalinSort = new StalinSort();
+        Integer[] input = {42};
+        Integer[] expected = {42};
+        Integer[] result = stalinSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+}