Top K Frequent Elements Using a Heap

A heap is a specialized tree-based data structure that satisfies the heap property: in a max-heap, every parent node is greater than or equal to its children, and in a min-heap, every parent is less than or equal to its children. Heaps are typically implemented as arrays where for a node at index i, its children are at indices 2i+1 and 2i+2, and its parent is at index (i-1)/2. The key operations are insert (add element and bubble up) and extract (remove root and bubble down), both running in O(l