O6Courses

package O7AssocietiveArrays.Exercise;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

public class O6Courses {
    public static void main(String[] args) throws IOException {
        BufferedReader reader =
            new BufferedReader(
                new InputStreamReader(
                    System.in
                )
            );

        LinkedHashMap<String, List<String>> courses = new LinkedHashMap<>();
        String input;

        while (!"end".equalsIgnoreCase(input = reader.readLine())) {
            String[] tokens = input.split("\\s+:\\s+");

            courses
                    .putIfAbsent(tokens[0], new ArrayList<>());

            courses
                    .get(tokens[0]).add(tokens[1]);


        }

                courses
                .entrySet()
                .stream()
                .sorted((meSecond, meFirst)->
                        Integer.compare(meFirst.getValue().size(),
                        meSecond.getValue().size()))

                .forEach(littleFuck-> {
                    System.out.println(
                            littleFuck.getKey() +
                                    ": " +
                                    littleFuck.getValue().size());
                    littleFuck
                            .getValue()
                            .stream()
                            .sorted(Comparator.naturalOrder())
                            .forEach(ej-> System.out.println("-- " + ej));
                        })
                ;


    }
}