Add ActivitySelection

Author: jcazevedo

src/main/java/com/packt/datastructuresandalg/lesson4/activityselection/ActivitySelection.java

@@ -0,0 +1,56 @@
+package com.packt.datastructuresandalg.lesson4.activityselection;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ActivitySelection {
+    static class Activity {
+        public int id;
+        public int start;
+        public int finish;
+
+        public Activity(int i, int s, int f) {
+            id = i;
+            start = s;
+            finish = f;
+        }
+    }
+
+    public List<Activity> select(List<Activity> activities) {
+        List<Activity> selected = new ArrayList<>();
+        List<Activity> sortedActivities = new ArrayList<>(activities);
+        Collections.sort(sortedActivities, (o1, o2) -> o1.finish < o2.finish ? -1 : o1.finish > o2.finish ? 1 : 0);
+        if (sortedActivities.size() > 0)
+            selected.add(sortedActivities.get(0));
+        for (int i = 1; i < sortedActivities.size(); i++)
+            if (sortedActivities.get(i).start >= selected.get(selected.size() - 1).finish)
+                selected.add(sortedActivities.get(i));
+        return selected;
+    }
+
+    public static void main(String[] args) {
+        List<Activity> activities = new ArrayList<>();
+        activities.add(new Activity(1, 600, 720));
+        activities.add(new Activity(2, 1200, 1380));
+        activities.add(new Activity(3, 1020, 1140));
+        activities.add(new Activity(4, 600, 630));
+        activities.add(new Activity(5, 1140, 1230));
+        activities.add(new Activity(6, 1290, 1380));
+        activities.add(new Activity(7, 750, 810));
+        activities.add(new Activity(8, 1200, 1320));
+        activities.add(new Activity(9, 1020, 1170));
+        activities.add(new Activity(10, 960, 1140));
+        activities.add(new Activity(11, 900, 1020));
+
+        ActivitySelection selection = new ActivitySelection();
+        List<Activity> selected = selection.select(activities);
+        for (int i = 0; i < selected.size(); i++) {
+            System.out.print(selected.get(i).id);
+            if (i + 1 < selected.size())
+                System.out.print(", ");
+            else
+                System.out.print("\n");
+        }
+    }
+}