4. Star Enigma - video

import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StarEnigma_04 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        //1. decrypt message
            //1.1 count of letters [s, t, a, r]
            //1.2 decrypt
        //2. извеличаме данни: planet, population, attack, soldierCount
        int n = Integer.parseInt(scanner.nextLine());
        String regex = "@(?<planet>[A-Za-z]+)[^@\\-!:>]*:(?<population>[0-9]+)[^@\\-!:>]*!(?<attack>[AD])![^@\\-!:>]*->(?<soldierCount>[0-9]+)";
        Pattern pattern = Pattern.compile(regex);

        List<String> attackers = new ArrayList<>(); //атакуващи планети
        List<String> destroyed = new ArrayList<>(); //разрушени планети
        for (int i = 1; i <= n; i++) {
            String encryptMessage = scanner.nextLine();
            int countLetters = getSpecialLetters(encryptMessage);
            String decryptedMessage = getDecryptedMessage(encryptMessage, countLetters);
            //PQ@Alderaa1:30000!A!->20000
            Matcher matcher = pattern.matcher(decryptedMessage);
            if(matcher.find()) {
                String planet = matcher.group("planet");
                int population = Integer.parseInt(matcher.group("population"));
                String attackType = matcher.group("attack");
                //A -> attackers
                //D -> destroyed
                if(attackType.equals("A")) {
                    attackers.add(planet);
                } else if (attackType.equals("D")){
                    destroyed.add(planet);
                }
                int soldierCount = Integer.parseInt(matcher.group("soldierCount"));
            }
        }
        //2 списъка с планети: атакуващи + унищожени
        System.out.println("Attacked planets: " + attackers.size());
        Collections.sort(attackers);
        attackers.forEach(planet -> System.out.println("-> " + planet));

        System.out.println("Destroyed planets: " + destroyed.size());
        Collections.sort(destroyed);
        destroyed.forEach(planet -> System.out.println("-> " + planet));
    }

    private static String getDecryptedMessage(String encryptMessage, int countLetters) {
        StringBuilder decryptMessage = new StringBuilder();
        //encrypt: STCDoghudd4=63333$D$0A53333
        //decrypt: PQ@Alderaa1:30000!A!->20000
        for (int i = 0; i < encryptMessage.length(); i++) {
            char currentSymbol = encryptMessage.charAt(i);
            decryptMessage.append((char)(currentSymbol - countLetters));
        }
        return decryptMessage.toString();
    }

    private static int getSpecialLetters(String encryptMessage) {
        //SsTtAaRr -> s t a r
        //STCDoghudd4=63333$D$0A53333 -> stcdoghudd4=63333$d$0a53333
        int counter = 0;
        String lowerCaseMessage = encryptMessage.toLowerCase();
        for (int i = 0; i < lowerCaseMessage.length(); i++) {
            char currentSymbol = lowerCaseMessage.charAt(i);
            if (currentSymbol == 's' ||
                currentSymbol == 'a' ||
                currentSymbol == 't' ||
                    currentSymbol == 'r') {
                counter++;
            }
        }
        return counter;
    }
}