What is a Heap? (Min-Heap and Max-Heap)

Difficulty: 3/10

heap operations, priority queue, array representation

Heap Data Structure

A heap is a complete binary tree satisfying the heap-order property. In a min-heap, every parent is less than or equal to its children, so the minimum element is at the root. In a max-heap, every parent is greater than or equal to its children, so the maximum is at the root. Heaps are commonly used to implement priority queues.

javascript

1
Heap is structurally a complete binary tree.
2
Min-heap exposes the minimum at the root.
3
Max-heap exposes the maximum at the root.
4
Insertion and deletion of the root take O(log n).
5
Peek at the root takes O(1).
6
Heaps are widely used in priority queues and scheduling.

Scenario Questions

0-2 years experience

1Suppose you need to implement a feature that always shows the next upcoming event in a calendar app. How would you use a min‑heap to retrieve the soonest event, and what is the time complexity of inserting a new event?
2If you have an array representing a max‑heap and you accidentally swap two elements, how does that affect the heap property and what steps would you take to restore it?
3When you pop the top element from a min‑heap, what changes occur in the underlying array representation?

Follow-up Questions

Can you walk me through the heapify process after removal?
What edge cases do you consider when the heap is empty or has one element?
How would you verify that your heap maintains the correct ordering after a series of operations?