Foundations line
Linked List problems
Nodes joined by pointers instead of positions in a list. The problems practice rewiring those pointers in place without losing the rest of the chain.
- 3 easy
- 6 medium
- 2 hard
The 11 problems
In the order the app teaches them. Each page has the problem, five hints and the explained solution.
- Reverse Linked ListEasy
- Merge Two Sorted ListsEasy
- Reorder ListMedium
- Remove Nth Node From End of ListMedium
- Copy List With Random PointerMedium
- Add Two NumbersMedium
- Linked List CycleEasy
- Find The Duplicate NumberMedium
- LRU CacheMedium
- Merge K Sorted ListsHard
- Reverse Nodes In K GroupHard
On the roadmap
Linked List is a station on the foundations line. It builds on Stack. Next comes Trees.
The roadmap says why each line runs in its order.
Patterns
5 patterns solve these problems. Naming them gives the problems’ methods away, so the list is folded.
Show the 5
- Linked list pointer rewiring5 problems
- Fast and slow pointers3 problems
- Hash map lookup1 problem
- Digit-by-digit arithmetic1 problem
- Purpose-built data structure1 problem