AlgoSolveoRoadmap › Stage 5: Recursion & Linked Lists › Pattern 23 of 53
DSA pattern guide
Linked List — Basics & Fast/Slow
Middle node, cycle detection, nth from end, intersection.
Use it when
Middle node, cycle detection, nth from end, intersection.
Key idea
Two pointers at different speeds or with a fixed gap. A dummy head removes edge cases.
Practice problems, in order
- Middle of the Linked ListEasy
- Linked List CycleEasy
- Intersection of Two Linked ListsEasy
- Remove Nth Node from EndMedium
- Linked List Cycle IIMedium
- Odd-Even Linked ListMedium
- Design Linked ListMedium
How to practise this pattern
- Read the problem and look for the signal above before writing any code.
- Say the brute force out loud, with its time complexity, then ask what work it repeats.
- Apply the key idea and write the optimised version yourself.
- If you're stuck for more than 10 minutes, take one small hint, not the full solution.
- Move to the next problem only when you can explain why this pattern fits.
Stuck on one of these?
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