Add GangScheduling algorithm (#5819)

Author: Hardvan

DIRECTORY.md

@@ -533,6 +533,7 @@
             * [EDFScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/EDFScheduling.java)
             * [FairShareScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/FairShareScheduling.java)
             * [FCFSScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/FCFSScheduling.java)
+            * [GangScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/GangScheduling.java)
             * [HighestResponseRatioNextScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/HighestResponseRatioNextScheduling.java)
             * [JobSchedulingWithDeadline](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/JobSchedulingWithDeadline.java)
             * [LotteryScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/LotteryScheduling.java)
@@ -1134,6 +1135,7 @@
             * [EDFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/EDFSchedulingTest.java)
             * [FairShareSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/FairShareSchedulingTest.java)
             * [FCFSSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/FCFSSchedulingTest.java)
+            * [GangSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/GangSchedulingTest.java)
             * [HighestResponseRatioNextSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/HighestResponseRatioNextSchedulingTest.java)
             * [JobSchedulingWithDeadlineTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/JobSchedulingWithDeadlineTest.java)
             * [LotterySchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/LotterySchedulingTest.java)

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

@@ -0,0 +1,61 @@
+package com.thealgorithms.scheduling;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * GangScheduling groups related tasks (gangs) to run simultaneously on multiple processors.
+ * All tasks in a gang are executed together or not at all.
+ *
+ * Use Case: Parallel computing environments where multiple threads of a program
+ * need to run concurrently for optimal performance.
+ *
+ * @author Hardvan
+ */
+public final class GangScheduling {
+
+    static class Gang {
+        String name;
+        List<String> tasks;
+
+        Gang(String name) {
+            this.name = name;
+            this.tasks = new ArrayList<>();
+        }
+
+        void addTask(String task) {
+            tasks.add(task);
+        }
+
+        List<String> getTasks() {
+            return tasks;
+        }
+    }
+
+    private final Map<String, Gang> gangs;
+
+    public GangScheduling() {
+        gangs = new HashMap<>();
+    }
+
+    public void addGang(String gangName) {
+        gangs.putIfAbsent(gangName, new Gang(gangName));
+    }
+
+    public void addTaskToGang(String gangName, String task) {
+        Gang gang = gangs.get(gangName);
+        if (gang != null) {
+            gang.addTask(task);
+        }
+    }
+
+    public Map<String, List<String>> getGangSchedules() {
+        Map<String, List<String>> schedules = new HashMap<>();
+        for (Gang gang : gangs.values()) {
+            schedules.put(gang.name, gang.getTasks());
+        }
+        return schedules;
+    }
+}

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

@@ -0,0 +1,52 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import java.util.Map;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class GangSchedulingTest {
+
+    private GangScheduling scheduler;
+
+    @BeforeEach
+    public void setup() {
+        scheduler = new GangScheduling();
+    }
+
+    @Test
+    public void testAddGangAndTask() {
+        scheduler.addGang("Gang1");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testMultipleGangs() {
+        scheduler.addGang("Gang1");
+        scheduler.addGang("Gang2");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        scheduler.addTaskToGang("Gang2", "Task2");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1"), "Gang2", List.of("Task2"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testGangWithMultipleTasks() {
+        scheduler.addGang("Gang1");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        scheduler.addTaskToGang("Gang1", "Task2");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1", "Task2"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testEmptyGangSchedule() {
+        scheduler.addGang("Gang1");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of());
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+}