Lowest Common Ancestor (Binary Tree, BST, Org Chart)

Also reported as LCA in Binary Tree

CodingAmazonLast reported October 2026Medium Frequency

Reported: 8× across candidate reports
First seen: October 2025
Last reported: October 2026
Reported outcome: mixed

Problem Overview

The round: eight Amazon reports, October 2025 to October 2026, from intern, new-grad, experienced-hire and L6 loops. Four are the plain version: two reports pin it to the binary-tree LeetCode 236 (a new-grad round, an SDE intern loop), and two more just say lowest common ancestor (an AWS intern, an…

3 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
The rest of the problem statement — full requirements, constraints, and edge cases
Approach and trade-offs — what passing candidates did, and the mistakes that sink people

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Verified Source

Every question is reconstructed from multiple independent candidate reports. Verbatim follow-ups, not invented ones.

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Interviewer Follow-ups

The exact follow-ups reported by candidates, with the trigger that prompts each one — plus the mistakes that sink people.