# Linked List

> Pointer manipulation, fast/slow, reversal.

Canonical: https://learn.significanthobbies.com/curriculum/concepts/linked-list

Pointer manipulation, fast/slow, reversal.

- Difficulty: intro
- Tracks: DSA & Implementation

## 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.



## Primary sources

- [VisuAlgo — Linked List](https://visualgo.net/en/list) (doc)

## Practice

### Reverse a linked list in place

Reverse singly linked list 1→2→3→null iteratively. Return new head.

**Expected evidence:** 3→2→1→null.

### 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.

## Review prompts

- What does a fast/slow pointer pair give you that a single pointer cannot?


## Prerequisites

- None assigned.

## Related concepts

- [Trees](https://learn.significanthobbies.com/curriculum/concepts/trees)

## Learning paths

- [DSA Practice](https://learn.significanthobbies.com/curriculum/roadmaps/dsa-practice)