feat: Add SpeculativeExecutionScheduling new algorithm with tests

DIRECTORY.md

@@ -563,6 +563,7 @@
             * [SelfAdjustingScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/SelfAdjustingScheduling.java)
             * [SJFScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/SJFScheduling.java)
             * [SlackTimeScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/SlackTimeScheduling.java)
+            * [SpeculativeExecutionScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/SpeculativeExecutionScheduling.java)
             * [SRTFScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/SRTFScheduling.java)
           * searches
             * [BinarySearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/BinarySearch.java)
@@ -597,6 +598,7 @@
             * [UnionFind](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/UnionFind.java)
             * [UpperBound](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/UpperBound.java)
           * slidingwindow
+            * [LongestSubarrayWithSumLessOrEqualToK](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/slidingwindow/LongestSubarrayWithSumLessOrEqualToK.java)
             * [LongestSubstringWithoutRepeatingCharacters](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/slidingwindow/LongestSubstringWithoutRepeatingCharacters.java)
             * [MaxSumKSizeSubarray](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/slidingwindow/MaxSumKSizeSubarray.java)
             * [MinSumKSizeSubarray](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/slidingwindow/MinSumKSizeSubarray.java)
@@ -1193,6 +1195,7 @@
             * [SelfAdjustingSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SelfAdjustingSchedulingTest.java)
             * [SJFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SJFSchedulingTest.java)
             * [SlackTimeSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SlackTimeSchedulingTest.java)
+            * [SpeculativeExecutionSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SpeculativeExecutionSchedulingTest.java)
             * [SRTFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SRTFSchedulingTest.java)
           * searches
             * [BinarySearch2dArrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java)
@@ -1228,6 +1231,7 @@
             * [UnionFindTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/UnionFindTest.java)
             * [UpperBoundTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/UpperBoundTest.java)
           * slidingwindow
+            * [LongestSubarrayWithSumLessOrEqualToKTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/slidingwindow/LongestSubarrayWithSumLessOrEqualToKTest.java)
             * [LongestSubstringWithoutRepeatingCharactersTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/slidingwindow/LongestSubstringWithoutRepeatingCharactersTest.java)
             * [MaxSumKSizeSubarrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/slidingwindow/MaxSumKSizeSubarrayTest.java)
             * [MinSumKSizeSubarrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/slidingwindow/MinSumKSizeSubarrayTest.java)

src/main/java/com/thealgorithms/scheduling/SpeculativeExecutionScheduling.java

@@ -0,0 +1,82 @@
+package com.thealgorithms.scheduling;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * SpeculativeExecutionScheduling runs multiple copies of the same task in parallel,
+ * picking the first one that finishes successfully. It is used to mitigate the
+ * impact of stragglers (slow tasks).
+ *
+ * Use Case: Big data systems like Hadoop and Spark, where it helps improve job completion time.
+ *
+ * @author Hardvan
+ */
+public final class SpeculativeExecutionScheduling {
+
+    static class Task {
+        String name;
+        boolean completed;
+        long startTime;
+
+        Task(String name) {
+            this.name = name;
+            this.completed = false;
+            this.startTime = -1;
+        }
+
+        void start() {
+            this.startTime = System.currentTimeMillis();
+        }
+
+        void complete() {
+            this.completed = true;
+        }
+
+        boolean hasStarted() {
+            return this.startTime != -1;
+        }
+    }
+
+    private final Map<String, List<Task>> taskGroups;
+
+    public SpeculativeExecutionScheduling() {
+        taskGroups = new HashMap<>();
+    }
+
+    /**
+     * Adds a task to the specified group.
+     *
+     * @param groupName the name of the group
+     * @param taskName  the name of the task
+     */
+    public void addTask(String groupName, String taskName) {
+        List<Task> tasks = taskGroups.computeIfAbsent(groupName, k -> new ArrayList<>());
+        tasks.add(new Task(taskName));
+    }
+
+    /**
+     * Executes the tasks in the specified group by assigning a start time.
+     *
+     * @param groupName the name of the group
+     * @return the name of the task that completed successfully
+     */
+    public String executeTasks(String groupName) {
+        List<Task> tasks = taskGroups.get(groupName);
+        if (tasks == null) {
+            return null;
+        }
+        for (Task task : tasks) {
+            if (!task.completed) {
+                if (!task.hasStarted()) {
+                    task.start();
+                }
+                task.complete();
+                return task.name + " started at " + task.startTime;
+            }
+        }
+        return null;
+    }
+}

src/test/java/com/thealgorithms/scheduling/SpeculativeExecutionSchedulingTest.java

@@ -0,0 +1,87 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class SpeculativeExecutionSchedulingTest {
+
+    private SpeculativeExecutionScheduling scheduler;
+
+    @BeforeEach
+    public void setup() {
+        scheduler = new SpeculativeExecutionScheduling();
+    }
+
+    @Test
+    public void testAddAndExecuteTask() {
+        scheduler.addTask("Group1", "Task1");
+
+        String result = scheduler.executeTasks("Group1");
+
+        // Check for null before splitting
+        if (result != null) {
+            String[] parts = result.split(" started at ");
+
+            // Validate task name and ensure start time is a valid timestamp
+            assertEquals("Task1", parts[0]);
+            assertTrue(Long.parseLong(parts[1]) > 0, "Start time should be greater than 0");
+        } else {
+            // Handle the case where result is null
+            assertTrue(false, "The result should not be null after executing the task.");
+        }
+    }
+
+    @Test
+    public void testMultipleTasksInGroup() {
+        scheduler.addTask("Group1", "Task1");
+        scheduler.addTask("Group1", "Task2");
+
+        // Execute the first task
+        String result1 = scheduler.executeTasks("Group1");
+
+        // Check for null before splitting
+        if (result1 != null) {
+            String[] parts1 = result1.split(" started at ");
+            assertEquals("Task1", parts1[0]);
+            assertTrue(Long.parseLong(parts1[1]) > 0, "Start time should be greater than 0");
+        } else {
+            // Handle the case where result1 is null
+            assertTrue(false, "The result for Task1 should not be null.");
+        }
+
+        // Execute the second task
+        String result2 = scheduler.executeTasks("Group1");
+
+        // Check for null before splitting
+        if (result2 != null) {
+            String[] parts2 = result2.split(" started at ");
+            assertEquals("Task2", parts2[0]);
+            assertTrue(Long.parseLong(parts2[1]) > 0, "Start time should be greater than 0");
+        } else {
+            // Handle the case where result2 is null
+            assertTrue(false, "The result for Task2 should not be null.");
+        }
+    }
+
+    @Test
+    public void testExecuteAllTasks() {
+        scheduler.addTask("Group1", "Task1");
+        scheduler.addTask("Group1", "Task2");
+
+        scheduler.executeTasks("Group1");
+        scheduler.executeTasks("Group1");
+
+        // Confirm executing tasks again returns null
+        assertNull(scheduler.executeTasks("Group1"));
+    }
+
+    @Test
+    public void testEmptyTaskGroup() {
+        // Confirm executing tasks on an empty group returns null
+        assertNull(scheduler.executeTasks("Group2"));
+    }
+}