DSA: Top-K Frequent Elements

Given an array, return the k most frequent elements. Explain the heap vs bucket-sort approaches and when each wins.

Technical Reference & Key Concepts

The Challenge: Top K Frequencies

Input: [1,1,1,2,2,3], k = 2 -> [1,2]. Explain your approach, complexity, and the alternatives.

Core questions to address:

  1. What is the first pass, and what does it give you?
  2. Compare the min-heap of size k vs sorting vs bucket sort — complexities and tradeoffs?
  3. When would each approach actually be the right choice in production?