How do you find Top K Frequent Elements?

Short answer: Count frequencies with a hash map. Then either use a min-heap of size k (O(n log k)) or bucket sort by frequency (O(n)) since frequencies are in 1..n.

Complexity

Heap O(n log k); bucket O(n).

Common follow-ups

• Top K frequent words (tie-break lexicographically)
• Kth largest element

Prefer bucket sort when you want to show O(n) mastery.