💥 Activity Selection Problem added

Author: darpanjbora

Greedy Algorithms/Activity Selection Problem/Activity.java

@@ -0,0 +1,20 @@
+class Activity implements Comparable<Activity> {
+     
+    Integer startTime = 0;
+    Integer finishTime = 0;
+
+     Activity(Integer st, Integer ft) {
+        startTime = st;
+        finishTime = ft;
+    }
+
+    @Override
+    public int compareTo(Activity activity) {
+        return this.finishTime.compareTo(activity.finishTime);
+    }
+
+    @Override
+    public String toString() {
+        return "(" + startTime + "," + finishTime + "), ";
+    }
+}

Greedy Algorithms/Activity Selection Problem/ActivitySelectionProblem.java

@@ -0,0 +1,48 @@
+/**
+ * You are given n activities with their start and finish times. 
+ * Select the maximum number of activities that can be performed by a single person, 
+ * assuming that a person can only work on a single activity at a time.
+ * 
+ * TIME COMPLEXITY : 
+ * O(n log n) time if input activities may not be sorted. 
+ * O(n) time when it is given that input activities are always sorted.
+ * 
+ */
+
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Random;
+
+public class ActivitySelectionProblem {
+    
+    public static void selectActivities() {
+
+        ArrayList<Activity> activities = new ArrayList<Activity>();
+
+        activities.add(new Activity(5,9));
+        activities.add(new Activity(1,2));
+        activities.add(new Activity(3,4));
+        activities.add(new Activity(0,6));
+        activities.add(new Activity(5,7));
+        activities.add(new Activity(8,9));
+        
+        Collections.sort(activities);
+
+        int st = -1;
+
+
+        System.out.print("\nSelected Activities are: [");
+        for (int i = 0; i < activities.size(); i++) {
+            if (activities.get(i).startTime >= st) {
+                System.out.print(activities.get(i));
+                st = activities.get(i).finishTime;
+            }
+        }
+        System.out.println("]\n");
+    }
+
+    public static void main(String[] args){
+         selectActivities();
+    }
+}