05. Courses

package Uprajneniq;

import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class StudentAcademy {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);


        Map<String, Set<String>> courses = new LinkedHashMap<>();

        String input;
        while (!(input = scanner.nextLine()).equals("end")) {
            String[] tokens = input.split(" : ");
            String courseName = tokens[0];
            String studentName = tokens[1];

            courses.putIfAbsent(courseName, new LinkedHashSet<>());
            courses.get(courseName).add(studentName);
        }

        for (Map.Entry<String, Set<String>> entry : courses.entrySet()) {
            String courseName = entry.getKey();
            Set<String> students = entry.getValue();
            System.out.printf("%s: %d%n", courseName, students.size());
            for (String studentName : students) {
                System.out.println("-- " + studentName);
            }
        }
    }
}