AlgoSolveoRoadmap › Stage 5: Recursion & Linked Lists › Pattern 25 of 53
DSA pattern guide
Linked List — Merge & Sort
Merge sorted lists, sort a list, reorder or partition.
Use it when
Merge sorted lists, sort a list, reorder or partition.
Key idea
Dummy head plus a tail pointer. Merge sort works naturally on lists by splitting at the middle.
Practice problems, in order
- Merge Two Sorted ListsEasy
- Remove Duplicates from Sorted ListEasy
- Add Two NumbersMedium
- Sort ListMedium
- Reorder ListMedium
- Partition ListMedium
- Copy List with Random PointerMedium
- Merge K Sorted ListsHard
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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