🧠 Before you code — what pattern fits?
Given the root of a binary tree, return its maximum depth: the number of nodes along the longest path from the root node down to the farthest leaf node.
[3,9,20,null,null,15,7] → 3
🎬 Video explanation · NeetCode
Your solution runs against 3 unit tests, including edge and large-value cases.
Loading...
Test console · 3 unit tests
Submit your code to run it against all 3 unit tests. Results appear here.
JavaScript, TypeScript & Python run sandboxed in your browser; other languages run on the execution server. Your code is saved locally as you type.
Want the full interview treatment — the conversation, the why, and step-by-step visuals? Read the deep dive →