You now understand linked list fundamentals: Core Techniques:
- Traversal with null checks
- Dummy head for cleaner code
- Three-pointer reversal
- Fast-slow pointer for middle and cycles
Patterns:
- Reversal: iterative with prev/current/next
- Cycle detection: fast catches slow inside cycle
- Merge: compare heads, append smaller
- LRU: hash map + doubly linked list
Complexity:
- Traversal: time, space
- Reversal: time, space iterative
- LRU operations: time
These pointer manipulation skills transfer directly to trees and graphs. Every tree traversal is linked list traversal with two next pointers instead of one.