Resolves Java Priority Queue Task

src/main/java/eu/ztsh/training/hackerrank/datastructures/priority_queue/Solution.java

@@ -0,0 +1,85 @@
+package eu.ztsh.training.hackerrank.datastructures.priority_queue;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+import java.util.PriorityQueue;
+import java.util.Scanner;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+class Priorities {
+
+    List<Student> getStudents(List<String> events) {
+        var queue = new PriorityQueue<>(events.size(),
+                Comparator.comparingDouble(Student::getCGPA)
+                        .reversed() // CGPA is the only descending here
+                        .thenComparing(Student::getName)
+                        .thenComparing(Student::getID));
+        events.forEach(event -> {
+            var line = event.split(" ");
+            switch (line[0]) {
+                case "ENTER" ->
+                        queue.add(new Student(Integer.parseInt(line[3]), line[1], Double.parseDouble(line[2])));
+                case "SERVED" -> queue.poll();
+                default -> throw new IllegalArgumentException();
+            }
+        });
+        return Stream.generate(queue::poll).takeWhile(Objects::nonNull).collect(Collectors.toList());
+    }
+
+}
+
+class Student {
+
+    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;
+    }
+
+    private final int id;
+    private final String name;
+    private final double cgpa;
+
+}
+
+// https://www.hackerrank.com/challenges/java-priority-queue/problem
+public class Solution {
+
+    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());
+            }
+        }
+    }
+    private static Scanner scan = new Scanner(System.in);
+    private final static Priorities priorities = new Priorities();
+
+}

src/test/java/eu/ztsh/training/hackerrank/HackerRankTest.java

@@ -10,6 +10,8 @@ import java.util.List;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 public abstract class HackerRankTest {
 
     @BeforeAll
@@ -25,6 +27,11 @@ public abstract class HackerRankTest {
         System.setIn(originalIn);
     }
 
+    protected void simpleAssert(List<String> input, List<String> expected) {
+        var result = invoke(input);
+        assertThat(result).containsExactlyElementsOf(expected);
+    }
+
     protected List<String> invoke(List<String> input) {
         try {
             outContent.reset();

src/test/java/eu/ztsh/training/hackerrank/SolutionClassDescription.java

@@ -4,7 +4,7 @@ import java.util.Arrays;
 
 public record SolutionClassDescription(Class<?> targetClass, String fieldName, FieldModifier[] modifiers) {
 
-    SolutionClassDescription(Class<?> targetClass) {
+    public SolutionClassDescription(Class<?> targetClass) {
         this(targetClass, null, null);
     }
 

src/test/java/eu/ztsh/training/hackerrank/datastructures/priority_queue/SolutionTest.java

@@ -0,0 +1,47 @@
+package eu.ztsh.training.hackerrank.datastructures.priority_queue;
+
+import java.util.List;
+import eu.ztsh.training.hackerrank.HackerRankTest;
+import eu.ztsh.training.hackerrank.SolutionClassDescription;
+import eu.ztsh.training.hackerrank.SolutionClassDescription.FieldModifier;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+@DisplayName("HackerRank chalenges: Java Priority Queue")
+class SolutionTest extends HackerRankTest {
+
+    @Test
+    public void testCase0() {
+        var input = List.of(
+                "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"
+        );
+        var expected = List.of(
+                "Dan",
+                "Ashley",
+                "Shafaet",
+                "Maria"
+        );
+        simpleAssert(input, expected);
+    }
+
+
+    @Override
+    protected SolutionClassDescription getSolutionClassDescription() {
+        return new SolutionClassDescription(Solution.class,
+                "scan",
+                new FieldModifier[]{FieldModifier.PRIVATE, FieldModifier.STATIC});
+    }
+
+}