Module Review: Linked Lists
You’ve mastered the chain. From scattered memory blocks to cycle detection, you now wield the power of pointers.
1. Key Takeaways
- Memory Reality: Linked Lists are cache-unfriendly. Arrays are usually faster in practice due to CPU caching.
- The Power: O(1) insertion/deletion if you have the pointer. No resizing cost.
- The Cost: O(N) access. No random access. Extra memory per node.
- Techniques:
- Dummy Node: Simplifies edge cases (head/tail).
- Two Pointers: Solve cycles, middle element, and kth-from-end.
- Three Pointers: Necessary for reversing a list.
2. Cheat Sheet
| Operation | Array | Singly Linked List | Doubly Linked List |
|---|---|---|---|
Access get(i) |
O(1) | O(N) | O(N) |
| Insert Head | O(N) | O(1) | O(1) |
| Insert Tail | O(1)* | O(N) (O(1) w/ tail ptr) | O(1) |
| Delete Mid | O(N) | O(N) | O(1) (given node) |
| Search | O(N) | O(N) | O(N) |
3. Interactive Flashcards
Test your knowledge. Click to flip.
What is the Time Complexity of accessing the Kth element in a Linked List?
O(N). You must traverse from the Head.
Why are Linked Lists "Cache Unfriendly"?
Nodes are scattered in memory, causing frequent CPU Cache Misses.
What is a Sentinel (Dummy) Node?
A placeholder node at the start of a list to simplify edge cases (like inserting into an empty list).
How do you detect a cycle in O(1) space?
Floyd's Cycle-Finding Algorithm (Tortoise and Hare).
What pointers do you need to reverse a Singly Linked List?
Prev, Curr, and Next.
4. Next Steps
Now that you understand the linear chain, it’s time to break the linearity. Next Module: Stacks & Queues - Building upon Linked Lists to create restricted access structures.
DSA Glossary
Module Review: Linked Lists
[!NOTE] This module explores the core principles of Module Review: Linked Lists, deriving solutions from first principles and hardware constraints to build world-class, production-ready expertise.
1. Practice in the Vault
Looking to solidify your understanding? Head over to the Problem Vault to solve curated problems related to this module with detailed walkthroughs and optimal solutions.