import java.util.*;
 
class TopKFrequentReadable {
 
    public static List<String> topKFrequent(String[] words, int k) {
        if (words == null || k <= 0) {
            return Collections.emptyList();
        }
 
        Map<String, Integer> freq = new HashMap<>();
        for (String w : words) {
            freq.put(w, freq.getOrDefault(w, 0) + 1);
        }
 
        List<String> uniqueWords = new ArrayList<>(freq.keySet());
 
        uniqueWords.sort(new Comparator<String>() {
            @Override
            public int compare(String a, String b) {
                int fa = freq.get(a);
                int fb = freq.get(b);
                if (fa != fb) {
                    return Integer.compare(fb, fa);
                }
                return a.compareTo(b);
            }
        });
 
        int end = Math.min(k, uniqueWords.size());
        return new ArrayList<>(uniqueWords.subList(0, end));
    }
 
    public static void main(String[] args) {
        String[] words1 = {"java", "python", "java", "golang", "java", "python"};
        System.out.println(topKFrequent(words1, 2)); // [java, python]
 
        String[] words2 = {"apple", "banana", "apple", "banana", "cherry"};
        System.out.println(topKFrequent(words2, 3)); // [apple, banana, cherry]
 
 
        System.out.println(topKFrequent(null, 2)); // []
        System.out.println(topKFrequent(new String[]{"x","y"}, 0)); // []
        System.out.println(topKFrequent(new String[]{"a","b","c"}, 10)); // returns all unique: [a,b,c]
    }
}
 
 

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