Enhance docs, add more tests in ArrayCombination (#5842)

Author: Hardvan

src/main/java/com/thealgorithms/bitmanipulation/IsPowerTwo.java

@@ -1,13 +1,27 @@
 package com.thealgorithms.bitmanipulation;
 
 /**
- * Is number power of 2
+ * Utility class for checking if a number is a power of two.
+ * A power of two is a number that can be expressed as 2^n where n is a non-negative integer.
+ * This class provides a method to determine if a given integer is a power of two using bit manipulation.
+ *
  * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
  */
-
 public final class IsPowerTwo {
     private IsPowerTwo() {
     }
+
+    /**
+     * Checks if the given integer is a power of two.
+     *
+     * A number is considered a power of two if it is greater than zero and
+     * has exactly one '1' bit in its binary representation. This method
+     * uses the property that for any power of two (n), the expression
+     * (n & (n - 1)) will be zero.
+     *
+     * @param number the integer to check
+     * @return true if the number is a power of two, false otherwise
+     */
     public static boolean isPowerTwo(int number) {
         if (number <= 0) {
             return false;

src/test/java/com/thealgorithms/bitmanipulation/IsPowerTwoTest.java

@@ -3,33 +3,49 @@
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-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;
 
 /**
  * Test case for IsPowerTwo class
  * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
  */
 
 public class IsPowerTwoTest {
-    @Test
-    public void testIsPowerTwo() {
-        // test some positive powers of 2
-        assertTrue(IsPowerTwo.isPowerTwo(1));
-        assertTrue(IsPowerTwo.isPowerTwo(2));
-        assertTrue(IsPowerTwo.isPowerTwo(4));
-        assertTrue(IsPowerTwo.isPowerTwo(16));
-        assertTrue(IsPowerTwo.isPowerTwo(1024));
 
-        // test some negative numbers
-        assertFalse(IsPowerTwo.isPowerTwo(-1));
-        assertFalse(IsPowerTwo.isPowerTwo(-2));
-        assertFalse(IsPowerTwo.isPowerTwo(-4));
+    @ParameterizedTest
+    @MethodSource("provideNumbersForPowerTwo")
+    public void testIsPowerTwo(int number, boolean expected) {
+        if (expected) {
+            assertTrue(IsPowerTwo.isPowerTwo(number));
+        } else {
+            assertFalse(IsPowerTwo.isPowerTwo(number));
+        }
+    }
 
-        // test some numbers that are not powers of 2
-        assertFalse(IsPowerTwo.isPowerTwo(0));
-        assertFalse(IsPowerTwo.isPowerTwo(3));
-        assertFalse(IsPowerTwo.isPowerTwo(5));
-        assertFalse(IsPowerTwo.isPowerTwo(15));
-        assertFalse(IsPowerTwo.isPowerTwo(1000));
+    private static Stream<Arguments> provideNumbersForPowerTwo() {
+        return Stream.of(Arguments.of(1, Boolean.TRUE), // 2^0
+            Arguments.of(2, Boolean.TRUE), // 2^1
+            Arguments.of(4, Boolean.TRUE), // 2^2
+            Arguments.of(8, Boolean.TRUE), // 2^3
+            Arguments.of(16, Boolean.TRUE), // 2^4
+            Arguments.of(32, Boolean.TRUE), // 2^5
+            Arguments.of(64, Boolean.TRUE), // 2^6
+            Arguments.of(128, Boolean.TRUE), // 2^7
+            Arguments.of(256, Boolean.TRUE), // 2^8
+            Arguments.of(1024, Boolean.TRUE), // 2^10
+            Arguments.of(0, Boolean.FALSE), // 0 is not a power of two
+            Arguments.of(-1, Boolean.FALSE), // Negative number
+            Arguments.of(-2, Boolean.FALSE), // Negative number
+            Arguments.of(-4, Boolean.FALSE), // Negative number
+            Arguments.of(3, Boolean.FALSE), // 3 is not a power of two
+            Arguments.of(5, Boolean.FALSE), // 5 is not a power of two
+            Arguments.of(6, Boolean.FALSE), // 6 is not a power of two
+            Arguments.of(15, Boolean.FALSE), // 15 is not a power of two
+            Arguments.of(1000, Boolean.FALSE), // 1000 is not a power of two
+            Arguments.of(1023, Boolean.FALSE) // 1023 is not a power of two
+        );
     }
 }