Java Priority Queue

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    import java.util.ArrayList;
    import java.util.List;
    import java.util.Scanner;
    import java.util.PriorityQueue;
    
    class Student implements Comparable<Student> {
        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;
        }
        
        public int compareTo(Student cStudent) {
            if (cgpa != cStudent.getCGPA()) {
                return Double.compare(cStudent.getCGPA(), cgpa);
            } else if (!name.equals(cStudent.getName())) {
                return name.compareTo(cStudent.getName());
            } else {
                return Integer.compare(id, cStudent.getId());
            }
        }
    }
    
    class Priorities {
        public List<Student> getStudents(List<String> events) {
            
            List<Student> servedStudents = new ArrayList<>();
            PriorityQueue<Student> queue = new PriorityQueue<Student>();
    
            for (String event : events) {
                String[] parsedEvent = event.split("\\s+");
                
                if ("ENTER".equals(parsedEvent[0])) {
                    Student student = new Student(
                        Integer.parseInt(parsedEvent[3]), parsedEvent[1], Double.parseDouble(parsedEvent[2]));
                    queue.add(student);
                } else if ("SERVED".equals(parsedEvent[0])) {
                    queue.poll();
                }
            }
    
            while (!queue.isEmpty()) {
                servedStudents.add(queue.poll());
            }
    
            return servedStudents;
        }
    }
    
    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());
                }
            }
        }
    }
    
  • + 1 comment
     class Student implements Comparable<Student> {
        
        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 this.id;
         }
         public String getName() {
            return this.name;
         }
         public double getCGPA(){
            return this.cgpa;
         }
       @Override
        public int compareTo(Student other) {
        if (this.cgpa != other.cgpa) return Double.compare(other.cgpa, this.cgpa);
        int nameComp = this.name.compareTo(other.name);
        if (nameComp != 0) return nameComp;
        return this.id - other.id;
    }
     }
     class Priorities {
        public List<Student> getStudents(List<String> events) {
            int idStudent = 0;
            PriorityQueue<Student> queue = new PriorityQueue<>();
            for (int i = 0; i < events.size(); i++) {
                if (events.get(i).startsWith("ENTER")) {
                    String[] parts = events.get(i).split(" ");
                    String name = parts[1];
                    double cgpa = Double.parseDouble(parts[2]);
                    idStudent++;
                    Student student = new Student(idStudent, name, cgpa);
                    queue.add(student);
                } else if (events.get(i).startsWith("SERVED")) {
                    queue.poll(); 
                }
            }
    
          
            List<Student> result = new ArrayList<>();
            while (!queue.isEmpty()) {
                result.add(queue.poll());
            }
            return result;
        }
    }
    
  • + 0 comments

    Java's PriorityQueue is a queue-based data structure that functions as a min-heap by default, where the head of the queue is the least element according to natural ordering or a specified comparator. It is part of the java.util package and implements the Queue interface. गोल्ड 365 लॉगिन

  • + 0 comments

    Here is Java Priority Queue solution - https://programmingoneonone.com/hackerrank-java-priority-queue-problem-solution.html

  • + 0 comments
    import java.io.*;
    import java.util.*;
    
    class Student {
        int id;
        String name;
        double cgpa;
    
        Student(int id, String name, double cgpa) {
            this.id = id;
            this.name = name;
            this.cgpa = cgpa;
        }
    }
    
    
    
    public class Solution {
        
        public static List<Student> solve(List<String> events){
            PriorityQueue<Student> pq= new PriorityQueue<>((a,b)->{
               if(a.cgpa!=b.cgpa) return Double.compare(b.cgpa, a.cgpa);
               if (!a.name.equals(b.name)) return a.name.compareTo(b.name);
               return Integer.compare(a.id, b.id);
                
            });
            
            for (String event : events) {
                String[] parts = event.split(" ");
                if (parts[0].equals("ENTER")) {
                    String name = parts[1];
                    double cgpa = Double.parseDouble(parts[2]);
                    int id = Integer.parseInt(parts[3]);
                    pq.add(new Student(id, name, cgpa));
                } else if (!pq.isEmpty()) {
                    pq.poll();
                }
            }
    
            List<Student> remaining = new ArrayList<>();
            while (!pq.isEmpty()) remaining.add(pq.poll());
            return remaining;
            
            
        };
    
        public static void main(String[] args) {
            /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
            
            Scanner sc = new Scanner(System.in);
            int n = Integer.parseInt(sc.nextLine());
            List<String> events = new ArrayList<>();
            while (n-- > 0) events.add(sc.nextLine());
            
            List<Student> st=solve(events);
             if (st.isEmpty()) System.out.println("EMPTY");
            else for (Student s : st) System.out.println(s.name);
            
            
            
            
        }
    }