Top K Frequent Elements

Description

https://leetcode.com/problems/top-k-frequent-elements/description/

Solution

import heapq


class Solution:
    def topKFrequent(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: List[int]
        """
        counter = {}
        for num in nums:
            if not counter.get(num):
                counter[num] = 1
            else:
                counter[num] += 1
        
        reverse_dic = {}
        for (key, value) in counter.items():
            neg_value = -value
            if not reverse_dic.get(neg_value):
                reverse_dic[neg_value] = [key]
            else:
                reverse_dic[neg_value].append(key)
        
        heap = list( reverse_dic.keys() )
        heapq.heapify(heap)
        ret = []
        while k > 0:
            value = heapq.heappop(heap)
            key_list = reverse_dic[value]
            k -= len(key_list)
            for key in key_list:
                ret.append(key)
                
        return ret