Problem context and objectives
Mission briefing
Archive pathfinder · Clues branch through a living archive
Explore only the branches that can still contain the answer: The Recursive Height.
Ignoring the parent-child rule turns a focused search into a full maze traversal.
How you win
- 1Recognize when Maximum tree depth by DFS matches the clues
- 2Keep this true after every move: depth(node) equals the number of nodes on the longest downward path beginning at node
- 3Reach the result within O(n) time and O(height) call space
Rules and pressure
- Target cost: O(n) time and O(height) call space
- State rule: depth(node) equals the number of nodes on the longest downward path beginning at node
Lesson 1 of 3
Predict the depth, then follow the returning child results. Null preserves missing child slots. Lesson questions refer to the original tree.
Each call returns the depth of its own subtree.
Your call · The root receives left=1 and right=2. What should it return?