Discussion on Java Priority Queue Challenge

Sort by

recency

|

257 Discussions

|

2 weeks ago+ 0 comments

using a linked list for the queue

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Comparator;

class Student{
    int id;
    String name;
    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 String getName(){
        return name;
    }
    public double getCGPA(){
        return cgpa;
    }
}

class Priorities{
    public List<Student> getStudents(List<String> events){
        LinkedList<Student> pq = new LinkedList<Student>(); 
  
        for(int i=0;i<events.size();i++){
            String[] entry = events.get(i).split("\\s+");
            
            if(entry[0].equals("ENTER")){

                Student s = new Student(Integer.parseInt(entry[3]), entry[1], Double.parseDouble(entry[2]));
                pq.add(s);
                
                
            }
            
            else if(entry[0].equals("SERVED")){
                //sort the queue first
                Collections.sort(pq, new CompareStudents());
                try{pq.removeFirst();}catch(Exception e){};
            }
        }
        return pq;
    }
}

class CompareStudents implements Comparator<Student>{
    public int compare(Student s1, Student s2){
        //sorting logic
        if(s1.cgpa<s2.cgpa){
            return 1;
        }
        if(s1.cgpa>s2.cgpa){
            return -1;
        }
        if(s1.name.compareTo(s2.name)!=0){
            return s1.name.compareTo(s2.name);
        }
       
        if(s1.id<s2.id){
            return -1;
        }
        if(s1.id>s2.id){
            return 1;
        }
        return 0;
    }
}




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

import java[dot]util[dot]PriorityQueue ;
import java[dot]util[dot]LinkedList ;
class Student {
    private int id;
    private String name;
    private double cgpa;
    public Student(String name, double cgpa,int id) {
        this.id = id;
        this.name = name;
        this.cgpa = cgpa;
    }
    public int getID(){return id;}
    public String getName(){return name;}
    public double getCGPA(){return cgpa;}
};
class Priorities {
    private PriorityQueue<Student> queue;
    public Priorities() {
        queue = new PriorityQueue<>((s1, s2) -> {
            int[] res = {Double.compare(s2.getCGPA(),
            s1.getCGPA()),s1.getName().compareTo(s2.getName()),
            Integer.compare(s1.getID(), s2.getID())};
            for (int r : res){if (r != 0){return r;}}
            return 0;});
    }
    public List<Student> getStudents(List<String> events) {
        for (String event : events) {String[] e = event.split(" ");
            if (e[0].equals("ENTER")) 
            {queue.add(
                new Student(e[1], Double.parseDouble(e[2]),Integer.parseInt(e[3]))
                );}
            else if (e[0].equals("SERVED")) {queue.poll();}}
            LinkedList<Student> StudentsLeft = new LinkedList<>();
            while (!queue.isEmpty()) {StudentsLeft.add(queue.poll());}
            return StudentsLeft;}
}

2 months ago+ 0 comments

There might be more SERVED events than ENTER events, even though it's logically inconsistent.

3 months ago+ 0 comments

In java 15:

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

class Priorities {

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

    PriorityQueue<Student> priorityQueue = new PriorityQueue<>(new Comparator<Student>() {
        public int compare(Student s1, Student s2) {
            return s1.getCGPA() != s2.getCGPA() ? s2.getCGPA() - s1.getCGPA() > 0 ? 1 : -1 : !s1.getName().equals(s2.getName()) ? s1.getName().compareTo(s2.getName()) :  s1.getID() > s2.getID() ? 1 : -1;
        }
    });

    for (String str: events) {
        String isENTER = str.split(" ")[0];

        if (isENTER.equals("ENTER")) {
            int id = Integer.parseInt(str.split(" ")[3]);
            String name = str.split(" ")[1];
            double cgpa = Double.parseDouble(str.split(" ")[2]);

            priorityQueue.add(new Student(id, name, cgpa));

        } else priorityQueue.poll();
    }

    List<Student> result = new ArrayList<>();

    while (!priorityQueue.isEmpty()) {
        result.add(priorityQueue.poll());
    }

    return result;
}

}

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;
}

int getID() {
    return id;
}

String getName() {
    return name;
}

double getCGPA() {
    return cgpa;
}

}

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());
                }
        }
}

}

3 months ago+ 0 comments

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 String getName(){
     return name;
 }

 public double getCGPA(){
     return cgpa;
 }

 @Override
 public int compareTo(Student s){
     if(cgpa==s.cgpa){
            if(name.compareTo(s.name)!=0){
                return name.compareTo(s.name);
            }else if(id>s.id){
                return 1;
            }else{
                return -1;
            }
        }else if(cgpa<s.cgpa){
            return 1;
        }else{
            return -1;
        }
 }

}

class Priorities{

 private PriorityQueue<Student> pq;
 public Priorities(){
     pq = new PriorityQueue<>();
 }

 public List<Student> getStudents(List<String> events){
     List<Student> result = new ArrayList<>();
     for(String event : events){
         String[] s = event.split(" ");
         String op = s[0];

         if(op.equals("ENTER")){
             Student stu = new Student(Integer.parseInt(s[3]),s[1],Double.parseDouble(s[2]));
             pq.add(stu);
         }else if(op.equals("SERVED")){
             pq.poll();
         }
     }
     Iterator iter = pq.iterator();
     while(iter.hasNext()){
         result.add(pq.poll());
     }

         return result;
     }
 }



     return result;
 }

}

Sort by

|

257 Discussions

|

Cookie support is required to access HackerRank