K Most Frequent Words Problem Statement

Given an array of N non-empty words and an integer K, return the K most frequent words sorted by their frequency from highest to lowest.

Example:

Input:

N = 6, K = 2
words = ["i", "love", "leetcode", "i", "love", "coding"]

Output:

["i", "love"]

Explanation:

The words "i" and "love" appear twice and are most frequent. The word "leetcode" appears once.

Constraints:

• 1 <= N <= 105
• 1 <= K <= number of unique words
• Words consist of only lowercase letters.

Note:

If two words have the same frequency, the lexicographically smaller word comes first.

Follow up:

Try solving it in O(N * logK) time and O(N) extra space.