Problem - Top K Frequent Elements

Given an integer array $nums$ and an integer $k$, return the $k$ most frequent elements. Example: $nums = [1,1,1,2,2,3]$, $k = 2$ Output: $[1,2]$ (1 appears 3 times, 2 appears 2 times) This combines frequency counting (hash maps) with the k-th element pattern (heaps).