Merge branch 'master' into refactor/BalancedBrackets

Author: alxkm

src/main/java/com/thealgorithms/others/ArrayLeftRotation.java

@@ -1,34 +1,44 @@
 package com.thealgorithms.others;
 
-/*
- * A left rotation operation on an array
- * shifts each of the array's elements
- * given integer n unit to the left.
+/**
+ * Provides a method to perform a left rotation on an array.
+ * A left rotation operation shifts each element of the array
+ * by a specified number of positions to the left.
  *
  * @author sangin-lee
  */
-
 public final class ArrayLeftRotation {
     private ArrayLeftRotation() {
     }
 
-    /*
-     * Returns the result of left rotation of given array arr and integer n
-     *
-     * @param arr : int[] given array
-     *
-     * @param n : int given integer
+    /**
+     * Performs a left rotation on the given array by the specified number of positions.
      *
-     * @return : int[] result of left rotation
+     * @param arr the array to be rotated
+     * @param n the number of positions to rotate the array to the left
+     * @return a new array containing the elements of the input array rotated to the left
      */
     public static int[] rotateLeft(int[] arr, int n) {
         int size = arr.length;
-        int[] dst = new int[size];
+
+        // Handle cases where array is empty or rotation count is zero
+        if (size == 0 || n <= 0) {
+            return arr.clone();
+        }
+
+        // Normalize the number of rotations
         n = n % size;
+        if (n == 0) {
+            return arr.clone();
+        }
+
+        int[] rotated = new int[size];
+
+        // Perform rotation
         for (int i = 0; i < size; i++) {
-            dst[i] = arr[n];
-            n = (n + 1) % size;
+            rotated[i] = arr[(i + n) % size];
         }
-        return dst;
+
+        return rotated;
     }
 }

src/main/java/com/thealgorithms/others/EulersFunction.java

@@ -1,24 +1,32 @@
 package com.thealgorithms.others;
 
 /**
- * @brief utility class for <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>
+ * Utility class for computing
+ * <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>.
  */
 public final class EulersFunction {
     private EulersFunction() {
     }
 
+    /**
+     * Validates that the input is a positive integer.
+     *
+     * @param n the input number to validate
+     * @throws IllegalArgumentException if {@code n} is non-positive
+     */
     private static void checkInput(int n) {
         if (n <= 0) {
             throw new IllegalArgumentException("n must be positive.");
         }
     }
 
     /**
-     * @brief computes the value of Euler's totient function for given input
-     * @details has time complexity of O(sqrt(n))
-     * @param n the input
-     * @exception IllegalArgumentException n is non-positive
-     * @return the value of Euler's totient function for the input
+     * Computes the value of Euler's totient function for a given input.
+     * This function has a time complexity of O(sqrt(n)).
+     *
+     * @param n the input number
+     * @return the value of Euler's totient function for the given input
+     * @throws IllegalArgumentException if {@code n} is non-positive
      */
     public static int getEuler(int n) {
         checkInput(n);

src/main/java/com/thealgorithms/stacks/DecimalToAnyUsingStack.java

@@ -6,50 +6,33 @@ public final class DecimalToAnyUsingStack {
     private DecimalToAnyUsingStack() {
     }
 
-    public static void main(String[] args) {
-        assert convert(0, 2).equals("0");
-        assert convert(30, 2).equals("11110");
-        assert convert(30, 8).equals("36");
-        assert convert(30, 10).equals("30");
-        assert convert(30, 16).equals("1E");
-    }
-
     /**
-     * Convert decimal number to another radix
+     * Convert a decimal number to another radix.
      *
      * @param number the number to be converted
      * @param radix the radix
-     * @return another radix
-     * @throws ArithmeticException if <tt>number</tt> or <tt>radius</tt> is
-     * invalid
+     * @return the number represented in the new radix as a String
+     * @throws IllegalArgumentException if <tt>number</tt> is negative or <tt>radix</tt> is not between 2 and 16 inclusive
      */
-    private static String convert(int number, int radix) {
+    public static String convert(int number, int radix) {
+        if (number < 0) {
+            throw new IllegalArgumentException("Number must be non-negative.");
+        }
         if (radix < 2 || radix > 16) {
-            throw new ArithmeticException(String.format("Invalid input -> number:%d,radius:%d", number, radix));
+            throw new IllegalArgumentException(String.format("Invalid radix: %d. Radix must be between 2 and 16.", radix));
+        }
+
+        if (number == 0) {
+            return "0";
         }
-        char[] tables = {
-            '0',
-            '1',
-            '2',
-            '3',
-            '4',
-            '5',
-            '6',
-            '7',
-            '8',
-            '9',
-            'A',
-            'B',
-            'C',
-            'D',
-            'E',
-            'F',
-        };
+
+        char[] tables = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
+
         Stack<Character> bits = new Stack<>();
-        do {
+        while (number > 0) {
             bits.push(tables[number % radix]);
             number = number / radix;
-        } while (number != 0);
+        }
 
         StringBuilder result = new StringBuilder();
         while (!bits.isEmpty()) {

src/test/java/com/thealgorithms/others/ArrayLeftRotationTest.java

@@ -44,4 +44,11 @@ void testForHigherSizeStep() {
         int[] result = ArrayLeftRotation.rotateLeft(arr, n);
         assertArrayEquals(expected, result);
     }
+
+    @Test
+    void testForEmptyArray() {
+        int[] arr = {};
+        int[] result = ArrayLeftRotation.rotateLeft(arr, 3);
+        assertArrayEquals(arr, result);
+    }
 }

src/test/java/com/thealgorithms/others/EulersFunctionTest.java

@@ -3,37 +3,31 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import java.util.HashMap;
-import org.junit.jupiter.api.Test;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 class EulersFunctionTest {
-    @Test
-    public void testGetEuler() {
-        HashMap<Integer, Integer> testCases = new HashMap<>();
-        testCases.put(1, 1);
-        testCases.put(2, 1);
-        testCases.put(3, 2);
-        testCases.put(4, 2);
-        testCases.put(5, 4);
-        testCases.put(6, 2);
-        testCases.put(10, 4);
-        testCases.put(21, 12);
-        testCases.put(69, 44);
-        testCases.put(47, 46);
-        testCases.put(46, 22);
-        testCases.put(55, 40);
-        testCases.put(34, 16);
-        testCases.put(20, 8);
-        testCases.put(20, 8);
-        testCases.put(1024, 512);
 
-        for (final var tc : testCases.entrySet()) {
-            assertEquals(tc.getValue(), EulersFunction.getEuler(tc.getKey()));
-        }
+    @ParameterizedTest
+    @MethodSource("provideNumbersForGetEuler")
+    void testGetEuler(int input, int expected) {
+        assertEquals(expected, EulersFunction.getEuler(input));
     }
 
-    @Test
-    public void testGetEulerThrowsExceptionForNonPositiveInput() {
-        assertThrows(IllegalArgumentException.class, () -> EulersFunction.getEuler(0));
+    @ParameterizedTest
+    @MethodSource("provideInvalidNumbersForGetEuler")
+    void testGetEulerThrowsExceptionForNonPositiveInput(int input) {
+        assertThrows(IllegalArgumentException.class, () -> EulersFunction.getEuler(input));
+    }
+
+    private static Stream<Arguments> provideNumbersForGetEuler() {
+        return Stream.of(Arguments.of(1, 1), Arguments.of(2, 1), Arguments.of(3, 2), Arguments.of(4, 2), Arguments.of(5, 4), Arguments.of(6, 2), Arguments.of(10, 4), Arguments.of(21, 12), Arguments.of(69, 44), Arguments.of(47, 46), Arguments.of(46, 22), Arguments.of(55, 40), Arguments.of(34, 16),
+            Arguments.of(20, 8), Arguments.of(1024, 512));
+    }
+
+    private static Stream<Arguments> provideInvalidNumbersForGetEuler() {
+        return Stream.of(Arguments.of(0), Arguments.of(-1), Arguments.of(-10));
     }
 }

src/test/java/com/thealgorithms/stacks/DecimalToAnyUsingStackTest.java

@@ -0,0 +1,45 @@
+package com.thealgorithms.stacks;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class DecimalToAnyUsingStackTest {
+
+    @Test
+    void testConvertToBinary() {
+        assertEquals("0", DecimalToAnyUsingStack.convert(0, 2));
+        assertEquals("11110", DecimalToAnyUsingStack.convert(30, 2));
+    }
+
+    @Test
+    void testConvertToOctal() {
+        assertEquals("36", DecimalToAnyUsingStack.convert(30, 8));
+    }
+
+    @Test
+    void testConvertToDecimal() {
+        assertEquals("30", DecimalToAnyUsingStack.convert(30, 10));
+    }
+
+    @Test
+    void testConvertToHexadecimal() {
+        assertEquals("1E", DecimalToAnyUsingStack.convert(30, 16));
+    }
+
+    @Test
+    void testInvalidRadix() {
+        IllegalArgumentException thrown = assertThrows(IllegalArgumentException.class, () -> DecimalToAnyUsingStack.convert(30, 1));
+        assertEquals("Invalid radix: 1. Radix must be between 2 and 16.", thrown.getMessage());
+
+        thrown = assertThrows(IllegalArgumentException.class, () -> DecimalToAnyUsingStack.convert(30, 17));
+        assertEquals("Invalid radix: 17. Radix must be between 2 and 16.", thrown.getMessage());
+    }
+
+    @Test
+    void testNegativeNumber() {
+        IllegalArgumentException thrown = assertThrows(IllegalArgumentException.class, () -> DecimalToAnyUsingStack.convert(-30, 2));
+        assertEquals("Number must be non-negative.", thrown.getMessage());
+    }
+}