In this HackerRank Java Priority Queue problem in the java programming language you need to Create the following two classes:
The Student class should implement:
- The constructor Student(int id, String name, double cgpa).
- The method int getID() to return the id of the student.
- The method String getName() to return the name of the student.
- The method double getCGPA() to return the CGPA of the student.
The Priorities class should implement the method List<Student> getStudents(List<String> events) to process all the given events and return all the students yet to be served in the priority order.
HackerRank Java Priority Queue problem solution.
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
/*
* Create the Student and Priorities classes here.
*/
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.*;
class Student implements Comparable<Student>{
String name = new String();
double cgpa;
int id;
public Student(String name,double cgpa,int id)
{
this.name = name;
this.cgpa = cgpa;
this.id = id;
}
public String getName(){
return this.name;
}
public int compareTo(Student s)
{
if(cgpa == s.cgpa)
{
if(name.compareTo(s.name) == 0)
{
if(id == s.id)
return 0;
else if (id > s.id)
return 1;
else
return -1;
}
else
return name.compareTo(s.name);
}
else if(cgpa > s.cgpa)
return -1;
else
return 1;
}
}
class Priorities{
public ArrayList<Student> getStudents(List<String> events)
{
int n = events.size();
PriorityQueue<Student> pq = new PriorityQueue<Student>();
for(String i:events)
{
String[] s = new String[4];
s = i.split("\s");
if(s.length>1)
{
pq.add(new Student(s[1],Double.valueOf(s[2]),Integer.valueOf(s[3])));
}
else
{
pq.poll();
}
}
while(pq.size()>1)
{
System.out.println(pq.poll().name);
}
return new ArrayList<Student>(pq);
}
}
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());
}
}
}
}
Second solution
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
class Student{
private int token;
private String fname;
private double cgpa;
public Student(int id, String fname, double cgpa) {
super();
this.token = id;
this.fname = fname;
this.cgpa = cgpa;
}
public int getToken() {
return token;
}
public String getFname() {
return fname;
}
public double getCgpa() {
return cgpa;
}
}
class StudentComparator implements Comparator<Student> {
public int compare(Student s1, Student s2) {
if (s1.getCgpa() > s2.getCgpa()) {
return -1;
}
if (s1.getCgpa() < s2.getCgpa()) {
return 1;
}
if (s1.getFname().compareTo(s2.getFname()) < 0) {
return -1;
}
if (s1.getFname().compareTo(s2.getFname()) > 0) {
return 1;
}
if (s1.getToken() < s2.getToken()) {
return -1;
}
if (s1.getToken() > s2.getToken()) {
return 1;
}
return 0;
}
}
public class Solution {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int totalEvents = Integer.parseInt(in.nextLine());
PriorityQueue<Student> pq = new PriorityQueue(totalEvents, new StudentComparator());
while(totalEvents>0){
String event = in.next();
if (event.equals("ENTER")) {
String fname = in.next();
double cgpa = in.nextDouble();
int id = in.nextInt();
Student s = new Student(id, fname, cgpa);
pq.add(s);
}
else {
pq.poll();
}
totalEvents--;
}
if (pq.isEmpty()) {
System.out.println("EMPTY");
}
while (!pq.isEmpty()) {
System.out.println(pq.poll().getFname());
}
}
}
The solution in java programming
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
class Student{
private int token;
private String fname;
private double cgpa;
public Student(int id, String fname, double cgpa) {
super();
this.token = id;
this.fname = fname;
this.cgpa = cgpa;
}
public int getToken() {
return token;
}
public String getFname() {
return fname;
}
public double getCgpa() {
return cgpa;
}
}
public class Solution {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int totalEvents = Integer.parseInt(in.nextLine());
PriorityQueue<Student> list =
new PriorityQueue<>(new Comparator<Student>() {
@Override
public int compare(Student o1, Student o2) {
if(o1.getCgpa() != o2.getCgpa())
return o1.getCgpa() < o2.getCgpa() ? 1 : -1;
else{
if(!o1.getFname().equals(o2.getFname()))
return o1.getFname().compareTo(o2.getFname());
else
return o1.getToken() < o2.getToken() ? 1 : -1;
}
}
});
while(totalEvents>0){
String event = in.next();
if(event.equals("ENTER")){
String name = in.next();
double gpa = in.nextDouble();
int id = in.nextInt();
list.add(new Student(id, name, gpa));
}else if(list.size() > 0 && event.equals("SERVED")){
list.remove();
}
totalEvents--;
}
if(list.size() == 0) {
System.out.println("EMPTY");
return;
}
while(list.size() > 0){
System.out.println(list.poll().getFname());
}
}
}