Stacks, Queues & Heaps
Stacks, queues, and heaps are fundamental data structures in computer science. A stack follows the Last-In-First-Out (LIFO) principle, allowing access to the most recently added item. A queue operates on the First-In-First-Out (FIFO) principle, processing elements in the order they arrive. A heap is a specialized tree-based structure that maintains a specific order, often used to efficiently retrieve the minimum or maximum element, supporting priority queue operations.
Stacks, Queues & Heaps
Stacks, queues, and heaps are fundamental data structures in computer science. A stack follows the Last-In-First-Out (LIFO) principle, allowing access to the most recently added item. A queue operates on the First-In-First-Out (FIFO) principle, processing elements in the order they arrive. A heap is a specialized tree-based structure that maintains a specific order, often used to efficiently retrieve the minimum or maximum element, supporting priority queue operations.
💡 Key Takeaways
- Understand stacks: LIFO access and common uses like undo histories and backtracking.
- Understand queues: FIFO processing for ordered tasks and streaming data.
- Learn what a heap is and how min-heap and max-heap variants prioritize items.
- Compare operation costs: stack push/pop and queue enqueue/dequeue are typically O(1); heap insert/extract are O(log n).
- Know when to choose each structure: stack for last-in access, queue for ordered processing, heap for prioritizing items.
❓ Frequently Asked Questions
What is a stack and how does it work?
A stack is a LIFO data structure where the last item pushed on top is the first removed. Core operations: push (add), pop (remove), and peek (view the top item).
What is a queue and how does it work?
A queue is a FIFO data structure where elements are processed in arrival order. Core operations: enqueue (add to rear), dequeue (remove from front), and peek (view the front item).
What is a heap and what is it used for?
A heap is a tree-based structure that maintains a heap property to support priority ordering (min-heap or max-heap). It’s commonly used to implement priority queues; supports insert and extract-min/max in O(log n).
How do stacks, queues, and heaps differ in use and ordering?
Stacks use LIFO order for backtracking or nested calls, queues use FIFO order for orderly processing, and heaps use priority order to efficiently access the highest/lowest-priority item.