class element:
    def __init__(self, freq, word):
        self.freq = freq
        self.word = word

    def __lt__(self, Element):
        if self.freq == Element.freq:
            return self.word > Element.word
        else:
            return self.freq < Element.freq

class Solution:
#TC: O(n logk) (almost O(n + klogk))
#SC: O(n)
#The pivotal part of this problem is to define an operation of "element"


    def topKFrequent(self, words: List[str], k: int) -> List[str]:
        Dict = {}
        for word in words:
            Dict[word] = Dict.get(word,0) + 1

        PQ = []
        for word in Dict.keys():
            Element = element(Dict[word], word)
            if len(PQ) < k:
                heapq.heappush(PQ, Element)
            else:
                if PQ[0].__lt__(Element):
                    heapq.heappop(PQ) 
                    heapq.heappush(PQ, Element) 

        res = []
        while len(PQ):
            res.append(PQ[0].word)
            heapq.heappop(PQ) 

        return res[::-1]