Linked Lists

Patterns to know:

• Fast/Slow Pointers (detect cycle, find middle).
• Dummy Node Technique.
• Reversal (full or partial).
• Merge Two/K Sorted Lists.

How to identify:

• Input involves nodes with .next.
• Questions about “cycle detection” or “reorder/reverse” → pointer tricks.
• Merging multiple lists → heap or divide & conquer.