Show how to add and remove elements from a min-heap, which always gives you the smallest element first.
Turn an unsorted list into a heap structure so the smallest element is always on top.
Find the k numbers that appear most often in an array.
In a grid where rows and columns are sorted, find the kth smallest number without sorting everything.
Figure out the maximum number of meetings happening at the same time, so you know how many rooms you need.
Combine k already-sorted lists into one single sorted list efficiently.
Find the kth largest number in an unsorted array without fully sorting it.
Schedule tasks so that identical tasks are at least n apart. Find the minimum total time including idle slots.