01 — problem
Flatten a Multilevel Doubly Linked List — LeetCode #?. Full problem statement, examples, and constraints live at https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list. PatternLens tracks this problem for pattern coverage and progress tracking.
02 — notes
Full examples and constraints live on the original LeetCode prompt. Use the link in the sidebar when you want the canonical statement.
03 — hints
Start by identifying the core linked list idea that reduces the search space.
If you get stuck, check whether a standard linked list technique applies here.