Maximum Depth of Binary Tree
A easy-tier problem at 77% community acceptance, tagged with Tree, Depth-First Search, Breadth-First Search. Reported in interviews at Yahoo and 15 others.
Maximum Depth of Binary Tree is the canonical warm-up tree problem, so you'd think it's harmless. But it appears in screens at Apple, Uber, LinkedIn, and Spotify often enough that blanking on the recursion or forgetting base cases costs you time you don't have. The 77% acceptance rate masks a real problem: candidates who haven't touched trees in months freeze on the first OA question. If you hit this live and your DFS logic breaks, StealthCoder solves it in seconds, invisible to the proctor, so you move to the actual hard problems.
Companies that ask "Maximum Depth of Binary Tree"
Maximum Depth of Binary Tree is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe trick is recognizing that depth is a recursive property: the depth of a node is 1 plus the maximum depth of its subtrees. Most candidates jump to iterative BFS first and write correct code, but then second-guess whether they need memoization or miss null checks. The pitfall is not handling empty trees or single nodes cleanly. DFS is simpler here: return 0 for null, then 1 plus max(left, right) for any node. Some people overengineer with level-order traversal when recursion takes three lines. The real hedge: if the problem mutates into 'find depth of a skewed tree' or 'handle None nodes', you already have the pattern locked. StealthCoder handles the edge cases and both Tree and Depth-First Search approaches, so even if you haven't drilled this specific problem, you walk through the assessment without panic.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Depth of Binary Tree recycles across companies for a reason. It's easy-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Maximum Depth of Binary Tree interview FAQ
Is this problem actually asked, or is it just on LeetCode?+
It's asked regularly at 10+ major companies including Apple, Uber, and LinkedIn. Usually as a first question to warm you up, not a blocker. The 77% acceptance rate reflects that it's easier than medium-level tree problems, but you still need clean code and no off-by-one errors.
Should I use recursion or iteration?+
Recursion is the natural fit and faster to code under pressure. DFS with a call stack is 3 lines. Iteration with BFS (queue) works too but takes longer to write correctly. In a live OA, recursion wins. Pick one, nail it, move on.
What's the most common mistake?+
Forgetting the base case (return 0 when node is None) or mixing up what 'depth' means. Some people return the height instead. Clarify: depth is the longest path from root to leaf. Off-by-one errors kill you here.
Does this relate to other tree problems I should know?+
Yes. This is the simplest tree-recursion template. Once you own this pattern, you can handle Maximum Path Sum, Diameter, and balanced-tree checks. It's the foundation. Nail this and the others become riffs.
If I blank on this during the OA, what do I do?+
Write the base case first (null node returns 0), then the recursive case (1 plus max of children). Test on a 3-node tree by hand. If you're truly stuck and time is slipping, StealthCoder reads the problem and surfaces a working solution in seconds, invisible to the proctor.
Want the actual problem statement? View "Maximum Depth of Binary Tree" on LeetCode →