Discussion on Java Priority Queue Challenge

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3 weeks ago+ 0 comments

import java.util.ArrayList; import java.util.List; import java.util.Scanner; import java.util.PriorityQueue;

/* * Create the Student and Priorities classes here. */

class Student implements Comparable{ private int id; private String name; private double cgpa;

public Student(int id, String name, double cgpa) {
    this.id = id;
    this.name = name;
    this.cgpa = cgpa;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public double getCgpa() {
    return cgpa;
}

public void setCgpa(double cgpa) {
    this.cgpa = cgpa;
}

public int compareTo(Student o){

    if (o.cgpa==this.cgpa && o.name==this.name){
       return Integer.compare(o.id,this.id);
    }else if (o.cgpa==this.cgpa){
        return this.name.compareTo(o.name);
    }else {
        return Double.compare( o.cgpa,this.cgpa);
    }


}

}

class Priorities {

public List<Student> getStudents(List<String> events) {

    PriorityQueue <Student> queue = new PriorityQueue<>();

    for (String event: events) {

        Scanner scanner= new Scanner(event);
        String command= scanner.next();

        switch (command){
            case "ENTER":
                String name=scanner.next();
                Double cgpa=scanner.nextDouble();
                int id=scanner.nextInt();
                Student student1= new Student(id,name,cgpa);
                queue.add(student1);

                break;

            case "SERVED":
                queue.poll();
                break;
        }
    }

    List<Student> studentList = new ArrayList<>();
    while (!queue.isEmpty()){
        studentList.add(queue.poll());
    }

    return studentList;
}

}

public class Solution { private final static Scanner scan = new Scanner(System.in); private final static Priorities priorities = new Priorities();

public static void main(String[] args) {
    int totalEvents = Integer.parseInt(scan.nextLine());    
    List<String> events = new ArrayList<>();

    while (totalEvents-- != 0) {
        String event = scan.nextLine();
        events.add(event);
    }

    List<Student> students = priorities.getStudents(events);

    if (students.isEmpty()) {
        System.out.println("EMPTY");
    } else {
        for (Student st: students) {
            System.out.println(st.getName());
        }
    }
}

}

4 weeks ago+ 0 comments

import java.util.Comparator;
import java.util.PriorityQueue;

class Student {
    private final int id;
    private final String name;
    private final double cgpa;

    public Student(int id, String name, double cgpa) {
        this.id = id;
        this.name = name;
        this.cgpa = cgpa;
    }

    public String getName() {
        return name;
    }

    public double getCgpa() {
        return cgpa;
    }

    public int getId() {
        return id;
    }
}

class Priorities {
    private static final String SERVED = "SERVED";

    public List<Student> getStudents(List<String> events) {
        PriorityQueue<Student> priority = getPriorityQueue(events);

        for (String s : events) {
            String[] t = s.split(" ");
            String event = t[0];
            if (event.equals(SERVED)) {
                priority.poll();
                continue;
            }

            String name = t[1];
            double cgpa = Double.parseDouble(t[2]);
            int id = Integer.parseInt(t[3]);

            Student student = new Student(id, name, cgpa);
            priority.add(student);
        }

        List<Student> students = new ArrayList<>();
        while (!priority.isEmpty()) {
            students.add(priority.poll());
        }
        return students;
    }

    private static PriorityQueue<Student> getPriorityQueue(List<String> events) {
        int size = events.size();
        Comparator<Student> pqComparator = new Comparator<Student>() {

            @Override
            public int compare(Student s1, Student s2) {
                return s1.getCgpa() != s2.getCgpa() ? Double.compare(s2.getCgpa(), s1.getCgpa())
                    : !s1.getName().equals(s2.getName()) ? s1.getName().compareTo(s2.getName())
                    : Integer.compare(s1.getId(), s2.getId());
            }
        };
        
        return new PriorityQueue<>(size, pqComparator);
    }
}

1 month ago+ 0 comments

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Queue;
import java.util.PriorityQueue;

class Student implements Comparable<Student>{
    private String name;
    private int id;
    private double cgpa;
    
    Student(int id, String name, double cgpa){
        this.id = id;
        this.name = name;
        this.cgpa = cgpa;
    }
    
    public int getId() {
        return id;
    }
    
    public double getCGPA() {
        return cgpa;
    }
    
    public String getName() {
        return name;
    }
    
    @Override
    public String toString(){
        return "name: " + name + ", id: " + id + ", cgpa: " + cgpa;
    }
    
    @Override
    public int compareTo(Student o){
        int cgpaCompare = Double.compare(o.cgpa, cgpa);
        
        if(cgpaCompare == 0){
            int nameCompare = name.compareTo(o.name);
            
            if(nameCompare == 0) return Integer.compare(o.id, id);
            return nameCompare;
        }
        
        return cgpaCompare;
    }
}

class Priorities{
    private Queue<Student> queue = new PriorityQueue<>();
    public List<Student> getStudents(List<String> events){
        
        List<Student> list = new ArrayList<>();
        for(String event: events){
            String[] array = event.split(" ");
            String action = array[0];
            String name = "";
            double cgpa = 0;
            int id = 0;
            
            if(array.length > 1){
                name = array[1];
                cgpa = Double.valueOf(array[2]);
                id = Integer.valueOf(array[3]);
            }
            
            Student student = new Student(id, name, cgpa);
            
            if(action.equals("ENTER")) {
                addStudent(student);
            }else{
                queue.poll();
            }
        }
                
        while(queue.size() > 0){
            list.add(queue.poll());
        }
        
        return list;
    }
    
    private void addStudent(Student student) {
        queue.add(student);
    } 
}

public class Solution {
    private final static Scanner scan = new Scanner(System.in);
    private final static Priorities priorities = new Priorities();
    
    public static void main(String[] args) {
        int totalEvents = Integer.parseInt(scan.nextLine());    
        List<String> events = new ArrayList<>();
        
        while (totalEvents-- != 0) {
            String event = scan.nextLine();
            events.add(event);
        }
        
        List<Student> students = priorities.getStudents(events);
        
        if (students.isEmpty()) {
            System.out.println("EMPTY");
        } else {
            for (Student st: students) {
                System.out.println(st.getName());
            }
        }
    }
}

2 months ago+ 0 comments

I think we may optimize little more

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.PriorityQueue;
import java.util.Comparator;

class Student {
    
    private int id;
    private String name;
    private double cgpa;
    
    Student(int id, String name, double cgpa) {
        this.id = id;
        this.name = name;
        this.cgpa = cgpa;
    }
    
    Student(String name, double cgpa, int id) {
        this(id, name, cgpa);
    }
    
    public int getID() {
        return id;
    }
    
    public String getName() {
        return name;
    }
    
    public double getCGPA() {
        return cgpa;
    }
    
}

class MyComparator implements Comparator<Student> {
    
    public int compare(Student s1, Student s2) {
        
        if (s1.getCGPA() == s2.getCGPA()) {
            if (s1.getName().equals(s2.getName())) {
                return s1.getID() - s2.getID();
            }
            return s1.getName().compareTo(s2.getName());
        }
            
        return s1.getCGPA() > s2.getCGPA() ? -1 : 1;
        
    }
    
}

class Priorities {
    
    public List<Student> getStudents(List<String> events) {
        
        List<Student> students = new ArrayList<>();
        
        boolean sorted = false;
        
        for (String event : events) {
            
           
            
            StringTokenizer st = new StringTokenizer(event);
            
            switch(st.nextToken()) {
                case "ENTER":
                    students.add(new Student(st.nextToken(), Double.parseDouble(st.nextToken()), Integer.parseInt(st.nextToken())));
                    sorted = false;
                    break;
                case "SERVED":
                    if (!sorted && students.size() > 1) {
                        students.sort(new MyComparator());
                        sorted = true;
                    }
                    if (!students.isEmpty()) {
                        students.remove(0);
                    }
                    break;    
            }
            
        }
        
        return students;
    }
    
}


public class Solution {
    private final static Scanner scan = new Scanner(System.in);
    private final static Priorities priorities = new Priorities();
    
    public static void main(String[] args) {
        int totalEvents = Integer.parseInt(scan.nextLine());    
        List<String> events = new ArrayList<>();
        
        while (totalEvents-- != 0) {
            String event = scan.nextLine();
            events.add(event);
        }
        
        List<Student> students = priorities.getStudents(events);
        
        if (students.isEmpty()) {
            System.out.println("EMPTY");
        } else {
            for (Student st: students) {
                System.out.println(st.getName());
            }
        }
    }
}

2 months ago+ 0 comments

I've been exploring Java Priority Queues lately, and they're as efficient as a well-trained confinement nanny singapore! Just like a nanny ensures a baby's needs are met in the right order, Priority Queues prioritize elements flawlessly. They're a must-learn for any Java enthusiast

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