Top K Frequent Elements

Medium Subject: Heap / Priority Queue

Time Complexity

O(N log K)

Space Complexity

O(N + K)

Problem Description

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

Optimal Solution

Python

from collections import Counter
import heapq

def topKFrequent(nums, k):
    count = Counter(nums)
    return [num for num, _ in heapq.nlargest(k, count.items(), key=lambda x: x[1])]