Top K Frequent Elements

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.

Example 1:

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

Example 2:

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

Constraints:

• 1 <= nums.length <= 105
• k is in the range [1, the number of unique elements in the array].
• It is guaranteed that the answer is unique.

Follow up: Your algorithm's time complexity must be better than O(n log n), where n is the array's size.

SOLUTION:

import heapq

class Solution:
    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
        freq = {}
        for num in nums:
            freq[num] = freq.get(num, 0) + 1
        klargest = heapq.nlargest(k, [(value, key) for key, value in freq.items()])
        return [item[1] for item in klargest]