Solution.java

class Solution {
    public List<String> topKFrequent(String[] words, int k) {
        Map<String, Integer> counter = new HashMap<>();
        for (String word : words) {
            counter.put(word, counter.getOrDefault(word, 0) + 1);
        }
        PriorityQueue<String> minHeap = new PriorityQueue<>((a, b) -> {
            if (counter.get(a).equals(counter.get(b))) {
                return b.compareTo(a);
            }
            return counter.get(a) - counter.get(b);
        });
        for (String word : counter.keySet()) {
            minHeap.offer(word);
            if (minHeap.size() > k) {
                minHeap.poll();
            }
        }
        List<String> res = new ArrayList<>();
        while (!minHeap.isEmpty()) {
            res.add(minHeap.poll());
        }
        Collections.reverse(res);
        return res;
    }
}