DSA & Implementation · intro
Linked List
Pointer manipulation, fast/slow, reversal.
Mental model
A linked list trades fast random access for fast inserts and deletes wherever you already have a pointer. The classic moves: a dummy head to simplify edge cases, two pointers (fast and slow), and reversing in place.
How to study Linked List
Begin by restating the mental model in your own words, then connect it to a concrete system you have built or operated. Name the mechanism, the constraint it addresses, and the trade-off it introduces. Use VisuAlgo — Linked List to check details, but close the source before writing your explanation. Retrieval is the learning step; rereading is only preparation.
Next, compare Linked List with Trees. Ask what changes in correctness, latency, resource use, operability, and failure recovery. Complete Reverse a linked list in place, Merge Two Sorted Lists and preserve the command, input, output, and one failed attempt as evidence. Finish by explaining the idea without jargon to someone who has not studied the track.
Proof of understanding
- Explain the mechanism from first principles and identify the state it reads or changes.
- Give one situation where the concept is the right choice and one where it is not.
- Predict a realistic failure mode before running the drill, then compare the prediction with evidence.
- Connect the result to a roadmap or build artifact instead of treating the concept as isolated trivia.
Learn from primary sources
- VisuAlgo — Linked List (doc)
Practice and explain it back
Reverse a linked list in place
Reverse singly linked list 1→2→3→null iteratively. Return new head.
Expected evidence: 3→2→1→null.
Open the interactive drill →Merge Two Sorted Lists
LeetCode #21 — Merge Two Sorted Lists. Solve on LeetCode, then implement here if you want it in your drill queue. https://leetcode.com/problems/merge-two-sorted-lists/
Expected evidence: Pass all LeetCode test cases for this problem.
Open the interactive drill →Review prompts
- What does a fast/slow pointer pair give you that a single pointer cannot?
Build evidence
Use a roadmap capstone to turn this concept into working evidence.
Prerequisites
None assigned yet.