Step-By-Step Directions From a Binary Tree Node to Another
A medium-tier problem at 56% community acceptance, tagged with String, Tree, Depth-First Search. Reported in interviews at Snowflake and 2 others.
You're given two nodes in a binary tree and asked to return step-by-step directions from one to the other. Snowflake, Databricks, and TikTok have all asked this. The problem looks simple until you realize you need to find the lowest common ancestor (LCA), build paths, then reverse one and concatenate. Most candidates get stuck on the path-building or LCA logic, especially under time pressure. If this lands in your OA and the tree traversal pattern doesn't click, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Step-By-Step Directions From a Binary Tree Node to Another"
Step-By-Step Directions From a Binary Tree Node to Another 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 that you can't just traverse from one node to the other. You have to find their lowest common ancestor, then build two paths: one from the source up to the LCA, and one from the LCA down to the target. The first path becomes all 'U' (up) moves; the second becomes directional moves (L or R). Most people try to solve it with a single traversal and fail. The real solution uses Depth-First Search to locate both nodes, record their paths, find where those paths diverge, reverse the first path, and merge them. Under interview pressure, the path-reversal logic trips people up. StealthCoder is the hedge if you blank on the LCA strategy or how to properly reconstruct the direction string.
Pattern tags
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Make sure you actually pass it.
Step-By-Step Directions From a Binary Tree Node to Another recycles across companies for a reason. It's medium-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.
Step-By-Step Directions From a Binary Tree Node to Another interview FAQ
Is this problem actually hard or just annoying?+
It's medium-annoying. The LCA concept is straightforward, but assembling the final direction string from two paths trips up half of candidates. The 56% acceptance rate reflects sloppy implementations, not conceptual difficulty. If you've drilled LCA and string concatenation, you'll pass it.
Do I need to memorize the LCA algorithm?+
Not memorize, but recognize. When you see 'path between two nodes in a tree', LCA is the pattern. Snowflake and Databricks both ask tree-path problems. If you can code a DFS that returns both path and node match, you're 80% there.
What's the most common mistake?+
Forgetting to reverse the path from source to LCA. Candidates build the paths correctly but concatenate them wrong, so directions go left when they should go up. Test your path-reversal logic before submitting.
Does this use any topic I won't see elsewhere?+
No. It combines Depth-First Search, Binary Tree navigation, and String manipulation. All three topics appear in other OAs at TikTok and Databricks. Master DFS on trees first, then this is a natural next step.
How long should I spend on this in an OA?+
15 to 20 minutes if you've seen LCA before. 25 to 30 if you haven't. If you're still debugging path-building after 30 minutes, that's when you know the pattern didn't stick. StealthCoder solves it in seconds if you're in that spot.
Want the actual problem statement? View "Step-By-Step Directions From a Binary Tree Node to Another" on LeetCode →