Sort Characters by Frequency
Sort characters in string by frequency using heap or bucket sort
Top K Frequent Elements
Given an integer array and k, return the k most frequent elements.
Top K Frequent Elements (LC 347) — Bucket Sort + Heap
Solve LeetCode 347 Top K Frequent Elements (Medium) with frequency map + bucket sort O(n) or min-heap O(n log k). Step-by-step for interviews.