queue-ds

Examination_queue.java

@@ -0,0 +1,104 @@
+import java.util.ArrayList;     
+import java.util.PriorityQueue;      
+import java.util.Scanner;        
+import java.util.List;                            
+import java.util.Comparator;         
+
+public class Examination_queue {     // Main class
+
+    private final static Scanner scan = new Scanner(System.in);
+    private final static Priorities priorities = new Priorities();
+
+    public static void main(String[] args) {
+
+        System.out.println("\n Enter number of entries");
+        int totalEntries = Integer.parseInt(scan.nextLine());   // To get number of entries in the queue
+
+        System.out.println("\n Input entries");  
+        System.out.println("\n  Name | GPA | Index No");
+
+        List<String> entries = new ArrayList<>();   //  Assign a array list as 'entries'
+
+        for (int i = totalEntries-1; i >= 0;  i -= 1) {
+            String name = scan.nextLine();
+            entries.add(name);      // Add entered names to the array list 
+        }
+
+        List<Examination> result_set = priorities.getResult(entries);      
+         System.out.println("\n --Result Sheet--\n"); 
+
+        if (result_set.isEmpty()) {  // Check if the queue is empty
+            System.out.println("No entries in the list");
+        } 
+
+        else {
+            System.out.println("Index No | GPA");
+            for (Examination sheet:result_set) {                         // iterate through each entry
+                System.out.println(sheet.getId()+" | "+sheet.getGpa());  // Print the index number and GPA of each candidate
+            }
+        }
+    }
+}
+
+class Examination {      // Class to get inputs                   
+    private int id;                                   
+    private float gpa;                   
+
+
+    public Examination(int id, float gpa) {
+        super();            // To call parent class constructor          
+        this.id = id;    
+        this.gpa = gpa;    
+    }
+
+    public int getId() {    // To return the index no 
+        return id;
+    }
+
+
+    public float getGpa() {  // To return GPA
+        return gpa;
+    }
+}
+
+
+class Priorities {      // Class to assign priorities
+
+    // Implement a method to process all the inputted entries and return the entries yet to be served in the priority order
+    public List < Examination > getResult(List < String > entries) {  
+
+        // Assign a queue as 'result_queue'
+        PriorityQueue < Examination > result_queue = new PriorityQueue(Comparator.comparing(Examination::getGpa).reversed().thenComparing(Examination::getId)); 
+                                                                       // The students having highest GPA is served first. 
+                                                                       // If any students having same GPA, served by index number ascending order.
+
+        List < Examination > result_set = new ArrayList < Examination > ();  // Assign a list 'result_set' to return entries at the end
+
+        for (String e: entries) {        // loop through the 'e' entries in list 'entries'
+            Scanner sc =new Scanner(e);  // To get total number of entries in the list
+
+                String name = sc.next();            
+                float gpa = sc.nextFloat();   
+                int id = sc.nextInt();
+
+                Examination examination = new Examination(id, gpa);
+                result_queue.add(examination);    // add 'id' and 'gpa' values to the queue
+
+        }
+
+        Examination first = result_queue.poll(); // To remove and return entries one by one from the queue
+        if (first == null) {                     // If no more entries in the list return the result set    
+            return result_set;   
+        } 
+        else {
+            while (first != null) {             // If there is another entry in the list,,
+
+                result_set.add(first);          // add it to the priority list,,
+                first = result_queue.poll();    // Remove and return added entry from the queue
+            }
+            return result_set;
+        }
+
+    }
+}
+