introductionToProgramming/week10/spellcheck/CzechSpellchecker.java

import java.util.Arrays;
import java.util.HashSet;

class CzechSpellchecker implements Spellchecker {
    public HashSet<String> words = new HashSet<String>(
            Arrays.asList("tři", "tisíce", "sta", "třicet", "stříbrných", "stříkaček", "stříkalo", "přes", "střech"));

    public boolean isWord(String word) {
        if (words.contains(word))
            return true;
        var lowercasedFirst = Character.toLowerCase(word.charAt(0)) + word.substring(1);
        if (words.contains(lowercasedFirst))
            return true;
        return false;
    }
}