01 — problem
All Nodes Distance K in Binary Tree — LeetCode #?. Full problem statement, examples, and constraints live at https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree. DSAPatterns 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 depth first search (dfs) idea that reduces the search space.
If you get stuck, check whether a standard depth first search (dfs) technique applies here.