Add SleepSort algorithm

- Implements Sleep Sort using thread-based timing approach
- Uses CountDownLatch for thread synchronization
- Includes basic test suite for functionality verification

Author: PauLopNun

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

@@ -0,0 +1,46 @@
+package com.thealgorithms.sorts;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Sleep Sort Algorithm Implementation
+ *
+ * @see <a href="https://rosettacode.org/wiki/Sorting_algorithms/Sleep_sort">Sleep Sort Algorithm</a>
+ */
+public final class SleepSort {
+
+    private SleepSort() {
+    }
+
+    public static int[] sort(int[] array) {
+        if (array == null || array.length == 0) {
+            return array;
+        }
+
+        int[] result = new int[array.length];
+        CountDownLatch latch = new CountDownLatch(array.length);
+        AtomicInteger index = new AtomicInteger(0);
+
+        for (int value : array) {
+            new Thread(() -> {
+                try {
+                    Thread.sleep(Math.abs(value) + 1);
+                    result[index.getAndIncrement()] = value;
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                } finally {
+                    latch.countDown();
+                }
+            }).start();
+        }
+
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+
+        return result;
+    }
+}

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

@@ -0,0 +1,32 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class SleepSortTest {
+
+    @Test
+    void testSleepSort() {
+        int[] input = {5, 3, 6, 2, 10};
+        int[] expected = {2, 3, 5, 6, 10};
+        int[] result = SleepSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void testEmptyArray() {
+        int[] input = {};
+        int[] expected = {};
+        int[] result = SleepSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void testSingleElement() {
+        int[] input = {42};
+        int[] expected = {42};
+        int[] result = SleepSort.sort(input);
+        assertArrayEquals(expected, result);
+    }
+}