Top K Frequent Elements.md

Given a non-empty array of integers, return the k most frequent elements.

Example 1:

Input: nums = [1,1,1,2,2,3], k = 2
Output: [1,2]
Example 2:

Input: nums = [1], k = 1
Output: [1]
Note:

You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
Your algorithm's time complexity must be better than O(n log n), where n is the array's size.

My code:

import collections
class Solution(object):
    def topKFrequent(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: List[int]
        """
        record_dict=collections.defaultdict()
        for item in nums:
            if item not in record_dict:
                record_dict[item]=1
            else:
                record_dict[item]+=1
        map_dict=collections.defaultdict(list)
        for item in record_dict.keys():
            map_dict[record_dict[item]].append(item)
        result=list(map_dict.keys())
        result.sort()
        result=result[::-1]#dec order
        i=0
        choose=0
        record=[]
        while i<k:
            value=result[choose]
            tmp_map=map_dict[value]
            for item in tmp_map:
                record.append(item)
                i+=1
            choose+=1
        record=record[:k]
        return record
            
        

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