07. Cities by Continent and Country

package Lekciq;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;

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


        int n = Integer.parseInt(scanner.nextLine());

        LinkedHashMap<String, LinkedHashMap<String, ArrayList<String>>> continents = new LinkedHashMap<>();

        for (int i = 0; i < n; i++) {
            String[] input = scanner.nextLine().split("\\s+");
            String continent = input[0];
            String country = input[1];
            String city = input[2];

            continents.putIfAbsent(continent, new LinkedHashMap<>());
            continents.get(continent).putIfAbsent(country, new ArrayList<>());
            continents.get(continent).get(country).add(city);
        }

        for (Map.Entry<String, LinkedHashMap<String, ArrayList<String>>> continentEntry : continents.entrySet()) {
            String continent = continentEntry.getKey();
            LinkedHashMap<String, ArrayList<String>> countries = continentEntry.getValue();

            System.out.println(continent + ":");

            for (Map.Entry<String, ArrayList<String>> countryEntry : countries.entrySet()) {
                String country = countryEntry.getKey();
                ArrayList<String> cities = countryEntry.getValue();

                System.out.print("  " + country + " -> ");
                System.out.println(String.join(", ", cities));
            }
        }
    }
}