This java file is solution to Core Java Assignment by UpGrad

assignment.java

import java.util.Scanner;
import java.util.ArrayList;

// Declaration of student type
class student
{
    String name;
    float GPA;
    int token=-1;

    void Enter(String name, float GPA, int token)
    {
        this.name = name;
        this.GPA = GPA;
        this.token = token;
    }
}

public class assignment
{
    public static void main(String [] args)
    {
        // Creating Queue using java.util.ArrayList
        ArrayList<student> arr = new ArrayList<student>();
        // Generating Scanner object for reading from stdin
        Scanner sc = new Scanner(System.in);
        
        int n;
        // Another Scanner object to avoid possible read errors that occur while using nextLine() method after using nextInt() method
        n = sc.nextInt();

        Scanner s = new Scanner(System.in);
        for (int i=0; i<n; i++)
        {
            // Scaning the line and storing it as String of Strings
            String [] event = s.nextLine().split(" ");
            
            // Event == "ENTER"
            if (event[0].toUpperCase().compareTo("ENTER") == 0)
            {
                // Getting the properties of object
                String name = event[1];
                float GPA = Float.parseFloat(event[2]);
                int token = Integer.parseInt(event[3]);
                int l = arr.size();
                
                // Creating new student object to add to queue
                student object = new student();
                object.Enter(name, GPA, token);
                
                // Arranging new object according to priority
                for (int j = 0; j < l; j++)
                {
                    boolean b1 = arr.get(j).GPA > GPA,
                        b2 = arr.get(j).GPA == GPA,
                        b3 = arr.get(j).name.compareTo(name) < 0,
                        b4 = arr.get(j).name.compareTo(name) == 0,
                        b5 = arr.get(j).token < token;
                    
                    if (b1 || (b2 && b3) || (b2 && b4 && b5))
                    {
                        arr.add(j, object);
                        break;
                    }     
                }
                
                // The new element is of highest priority
                if (l == arr.size())
                    arr.add(object);
            }    
            
            // event "SERVED"
            else 
                if(arr.size() > 0)
                    arr.remove(arr.size()-1);  
        }
        
        // releasing Scanner objects
        s.close();
        sc.close();
        
        // print the resulting queue
        if (arr.size() > 0)
            for (int i=arr.size()-1; i>=0; i--)
                System.out.println(arr.get(i).name);
        else
            System.out.println("EMPTY");
    }
}

Problem.txt

In this problem, there are types of events: ENTER (a student enters the queue) or SERVED.
A unique token is assigned to any student entering the queue. The queue serves the students 
based on the following criteria:
The student having the highest Cumulative Grade Point Average (CGPA) is served first.
Any students having the same CGPA will be served by name in ascending case-sensitive alphabetical order.
Any students having the same CGPA and name will be served in ascending token order.
Given a sequence of  events, print the names of students who are yet to be served(based on above criteria). 
If the queue is empty, print EMPTY.

Input Format
The first line of input contains an integer, , denoting the total number of events. 
Each of the subsequent lines will be of the following two forms:
ENTER name CGPA token - The student to be inserted into the priority queue.
SERVED - The highest priority student in the queue was served.

Constraints
 where 
 where each token i is a unique integer.

Output Format
Print the names (based on the criteria) of the students who are not served at all after executing all  events; if every student in the queue was served, then print EMPTY.

Sample Input
12
ENTER John 3.75 50
ENTER Mark 3.8 24
ENTER Shafaet 3.7 35
SERVED
SERVED
ENTER Samiha 3.85 36
SERVED
ENTER Ashley 3.9 42
ENTER Maria 3.6 46
ENTER Anik 3.95 49
ENTER Dan 3.95 50
SERVED

Sample Output
Dan
Ashley
Shafaet
Maria