Feature/swap using xor : Add swap numbers using xor algo with JUnit tests

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

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+package com.thealgorithms.bitmanipulation;
+
+/**
+ * <pre>
+ * This class provides a method to swap two numbers using XOR without creating a third variable.
+ * 
+ * The XOR swap algorithm works as follows:
+ * 
+ * Let's say we have two numbers, a and b.
+ * 
+ * Step 1: a = a ^ b
+ * - This step stores the XOR of a and b in a.
+ * - Example: If a = 5 (0101 in binary) and b = 3 (0011 in binary),
+ *   then a = 5 ^ 3 = 6 (0110 in binary).
+ * 
+ * Step 2: b = a ^ b
+ * - This step updates b to the original value of a.
+ * - Example: Now a = 6 (0110 in binary) and b = 3 (0011 in binary),
+ *   then b = 6 ^ 3 = 5 (0101 in binary).
+ * 
+ * Step 3: a = a ^ b
+ * - This step updates a to the original value of b.
+ * - Example: Now a = 6 (0110 in binary) and b = 5 (0101 in binary),
+ *   then a = 6 ^ 5 = 3 (0011 in binary).
+ * 
+ * After these three steps, the values of a and b are swapped.
+ * 
+ * For more information, refer to the 
+ * <a href="https://en.wikipedia.org/wiki/XOR_swap_algorithm"> XOR swap algorithm </a>.
+ * 
+ * Example usage:
+ * <code>
+ * int[] result = SwapNumbersUsingXor.swap(5, 3);<br>
+ * System.out.println("After swap: a = " + result[0] + ", b = " + result[1]);
+ * </code>
+ * </pre>
+ */
+public class SwapNumbersUsingXor {
+
+    /**
+     * Swaps two numbers using XOR.
+     *
+     * @param a the first number
+     * @param b the second number
+     * @return an array containing the swapped numbers
+     */
+    public static int[] swap(int a, int b) {
+        a = a ^ b; // Step 1
+        b = a ^ b; // Step 2
+        a = a ^ b; // Step 3
+        return new int[]{a, b};
+    }
+}

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

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+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the SwapNumbersUsingXor class.
+ */
+public class SwapNumbersUsingXorTest {
+
+    /**
+     * Test the swap method with positive numbers.
+     */
+    @Test
+    public void testSwapPositiveNumbers() {
+        int[] result = SwapNumbersUsingXor.swap(5, 3);
+        assertArrayEquals(new int[]{3, 5}, result);
+    }
+
+    /**
+     * Test the swap method with negative numbers.
+     */
+    @Test
+    public void testSwapNegativeNumbers() {
+        int[] result = SwapNumbersUsingXor.swap(-5, -3);
+        assertArrayEquals(new int[]{-3, -5}, result);
+    }
+
+    /**
+     * Test the swap method with a positive and a negative number.
+     */
+    @Test
+    public void testSwapPositiveAndNegativeNumbers() {
+        int[] result = SwapNumbersUsingXor.swap(5, -3);
+        assertArrayEquals(new int[]{-3, 5}, result);
+    }
+
+    /**
+     * Test the swap method with zero.
+     */
+    @Test
+    public void testSwapWithZero() {
+        int[] result = SwapNumbersUsingXor.swap(0, 3);
+        assertArrayEquals(new int[]{3, 0}, result);
+    }
+}