Binary Tree Longest Consecutive Sequence
A medium-tier problem at 54% community acceptance, tagged with Tree, Depth-First Search, Binary Tree. Reported in interviews at Walmart Labs and 1 others.
Binary Tree Longest Consecutive Sequence shows up in Walmart Labs and TikTok assessments. The problem asks you to find the longest path where each node's value is exactly one more than its parent's value. Most candidates see "tree" and reach for standard traversal, then realize the trick is tracking node-to-node arithmetic relationships during DFS, not just visiting nodes. If this one lands in your OA and the pattern doesn't click immediately, StealthCoder surfaces a working solution in seconds while the proctor sees nothing.
Companies that ask "Binary Tree Longest Consecutive Sequence"
Binary Tree Longest Consecutive Sequence 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 by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe core difficulty is that you can't just count nodes or find max depth. You need to track whether the current node's value is parent-plus-one while recursing. The obvious mistake is treating it like a standard tree traversal and forgetting to reset the consecutive count when the arithmetic relationship breaks. The real pattern: pass both the current node and the expected next value down the recursion stack. When they match, increment the count; when they don't, restart from one. DFS naturally handles this, but only if you thread the logic correctly. About 54% of candidates get this on first try, which means the remaining 46% either miss the parent-child value check or mismanage state. When you hit this live and blank on the reset logic, StealthCoder gives you the exact DFS skeleton with the counter management baked in.
Pattern tags
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Binary Tree Longest Consecutive Sequence 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 by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Binary Tree Longest Consecutive Sequence interview FAQ
How is this different from a standard tree max-depth problem?+
Standard max-depth counts any path. This problem only counts paths where each node is exactly one more than its parent. You must check arithmetic relationships, not just traverse. Reset your counter whenever that relationship breaks, or you'll get wildly wrong answers.
Is this really asked at Walmart Labs and TikTok?+
Yes, both companies have reported this problem. It's not rare, but it's also not in the super-common tier. If you see a tree problem in one of their assessments, this pattern should be in your mental toolkit.
What's the trap that catches most people?+
Forgetting to reset the consecutive count when a node breaks the sequence. You might track the longest sequence correctly for one branch, then accidentally carry over the count to an unrelated subtree. Always reset to 1 when the value relationship fails.
Do I need to return the actual path or just the length?+
The standard version asks for the length only, not the path itself. If your assessment asks for the path, the approach is similar but you'd store node references instead of just tracking counts. Check your problem statement carefully.
How does DFS help here compared to BFS?+
DFS lets you pass state (current count and expected next value) naturally down the recursion stack. BFS requires manual queue management to track that state. DFS is simpler for this pattern because parent-child relationships are implicit in the call stack.
Want the actual problem statement? View "Binary Tree Longest Consecutive Sequence" on LeetCode →