09. Population Counter

package Uprajnenie;

import java.util.LinkedHashMap;
import java.util.Scanner;

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


        String input = "";
        LinkedHashMap<String , LinkedHashMap<String, Long>> countriesAndCities = new LinkedHashMap<>();
        LinkedHashMap<String, Long> countriesOnly = new LinkedHashMap<>();

        // Read input until "report" is encountered
        while(!(input = scanner.nextLine()).equals("report")){
            String [] data = input.split("\\|");
            String city = data[0];
            String country = data[1];
            Long population = Long.parseLong(data[2]);

            // If country is encountered for the first time, initialize its city map and population count
            if(!countriesAndCities.containsKey(country)){
                countriesAndCities.put(country,new LinkedHashMap<>());
                countriesOnly.put(country, 0L);
            }
            // Update total population count for the country
            countriesOnly.put(country,countriesOnly.get(country)+population);
            // Add city population to the city map of the country
            if(!countriesAndCities.get(country).containsKey(city)){
                countriesAndCities.get(country).put(city,population);
            }
        }

        // Sort countries by total population in descending order and print aggregated data
        countriesAndCities.entrySet().stream()
                .sorted((c1,c2)-> countriesOnly.get(c2.getKey()).compareTo(countriesOnly.get(c1.getKey())))
                .forEach(country ->{
                    System.out.format("%s (total population: %d)\n",country.getKey(),countriesOnly.get(country.getKey()));
                    country.getValue().entrySet()
                            .stream().sorted((t1,t2)-> t2.getValue().compareTo(t1.getValue())).forEach(city ->{
                                System.out.format("=>%s: %d\n", city.getKey(),city.getValue());
                            });
                });

        scanner.close();
    }
}