feat: Add SpeculativeExecutionScheduling new algorithm with Junit tests

Author: Hardvan

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

@@ -0,0 +1,57 @@
+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;
+
+        Task(String name) {
+            this.name = name;
+            this.completed = false;
+        }
+
+        void complete() {
+            this.completed = true;
+        }
+    }
+
+    private final Map<String, List<Task>> taskGroups;
+
+    public SpeculativeExecutionScheduling() {
+        taskGroups = new HashMap<>();
+    }
+
+    public void addTask(String groupName, String taskName) {
+        taskGroups.putIfAbsent(groupName, new ArrayList<>());
+        taskGroups.get(groupName).add(new Task(taskName));
+    }
+
+    public String executeTasks(String groupName) {
+        List<Task> tasks = taskGroups.get(groupName);
+        if (tasks == null) {
+            return null;
+        }
+        for (Task task : tasks) {
+            if (!task.completed) {
+                task.complete();
+                return task.name;
+            }
+        }
+        return null;
+    }
+}

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

@@ -0,0 +1,45 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+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");
+        assertEquals("Task1", scheduler.executeTasks("Group1"));
+    }
+
+    @Test
+    public void testMultipleTasksInGroup() {
+        scheduler.addTask("Group1", "Task1");
+        scheduler.addTask("Group1", "Task2");
+        assertEquals("Task1", scheduler.executeTasks("Group1"));
+        assertEquals("Task2", scheduler.executeTasks("Group1"));
+    }
+
+    @Test
+    public void testExecuteAllTasks() {
+        scheduler.addTask("Group1", "Task1");
+        scheduler.addTask("Group1", "Task2");
+        scheduler.executeTasks("Group1");
+        scheduler.executeTasks("Group1");
+        assertNull(scheduler.executeTasks("Group1"));
+    }
+
+    @Test
+    public void testEmptyTaskGroup() {
+        assertNull(scheduler.executeTasks("Group2"));
+    }
+}