Create JobSequncingalgo.java

algorithms/Java/dynamic_programming/JobSequncingalgo.java

@@ -0,0 +1,74 @@
+import java.util.*;
+
+public class JobSequncing {
+
+    public static class Job{                        //Using a new class "Job"
+        String job_id;int deadline;int profit;
+        Job(String id, int pro, int dl){
+            deadline=dl;job_id=id;profit=pro;
+        }
+    }
+
+    public static void JobSequencingAlgo(ArrayList<Job> arr) {    
+        Collections.sort(arr, (a,b) -> {                    //Sorting array on basis of deadlines
+            return a.deadline-b.deadline;
+        });
+        //Printarray(arr);
+        ArrayList<Job> result = new ArrayList<>();          // initialise the result array and maxHeap
+        PriorityQueue<Job> MaxHeap = new PriorityQueue<>((a, b) -> { return b.profit - a.profit; });
+        for(int i=arr.size()-1;i>=0;i--){                   //starting iteration from end
+            int slot_ava;
+            if(i==0){                                       //slots between deadlines
+                slot_ava=arr.get(i).deadline;
+            }else{
+                slot_ava=arr.get(i).deadline - arr.get(i-1).deadline;
+            }
+            MaxHeap.add(arr.get(i));                        // include the profit of job(as priority), deadline and job_id in maxHeap
+            while(slot_ava>0 && MaxHeap.size()>0){
+                Job job = MaxHeap.remove();                 // get the job with max_profit
+                slot_ava--;                                 // reduce the slots
+                result.add(job);                            // include the job in the result array
+            }
+        }
+        Collections.sort(result, (a, b) -> {                //once again sort the result array by their deadlines
+            return a.deadline - b.deadline;
+        });
+        int totalprofit=0;
+        System.out.print("Hence, work will be done in order <");
+        for (Job job : result) {
+            totalprofit=totalprofit+job.profit;
+            System.out.print(job.job_id + " ");
+        }
+        System.out.println("> and thus the total profit gain is "+totalprofit);
+        System.out.println();
+    }
+
+    public static void Printtable(ArrayList<Job> arr) {
+        System.out.println("\nHence, we have -> ");
+        System.out.println("\nJob Index         Profit         Deadline\n");
+        for(int j=0;j<arr.size();j++){
+            System.out.println("   "+arr.get(j).job_id+" ".repeat(16-(arr.get(j).job_id).length())+arr.get(j).profit+" ".repeat(17-String.valueOf(arr.get(j).profit).length())+arr.get(j).deadline);
+        }
+        System.out.println();
+    }
+
+    /*public static void Printarray(ArrayList<Job> arr) {                                         //Function to print sorted array
+        System.out.println();
+        for(int j=0;j<arr.size();j++){
+            System.out.println(arr.get(j).job_id+" "+arr.get(j).profit+" "+arr.get(j).deadline);
+        }
+    }*/
+
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        System.out.print("Enter number of jobs -> ");int jobs = scan.nextInt();
+        ArrayList<Job> jobarr = new ArrayList<Job>();       //Not using Vector bcause it is single threaded and slow in performance
+        for(int i=0;i<jobs;i++){
+            System.out.println("\nFor Job "+(i+1)+" ->");
+            System.out.print("\nEnter the profit and deadline (space separated) ->");
+            jobarr.add(new Job("J"+(i+1), scan.nextInt(), scan.nextInt()));
+        }scan.close();
+        Printtable(jobarr);
+        JobSequencingAlgo(jobarr);
+    }
+}