# Tree Node — SQL interview question Aced (formerly Exponent) publishes a public search API over its indexed pages; the guide is at https://www.aced.io/agents/agent-access. Source: https://www.aced.io/questions/3957/tree-node Source observed: 2026-11-04T21:34:38.072Z Last checked: 2026-11-04T21:34:38.072+00:00 Indexed: 2026-11-05T01:45:45.549+00:00 --- # Tree Node **Difficulty:** Easy **Category:** Coding; SQL **Roles:** [Software Engineer (9)](https://www.aced.io/questions?role=swe), [Machine Learning Engineer](https://www.aced.io/questions?role=ml-engineer) **Companies represented:** [Amazon (2)](https://www.aced.io/questions?company=amazon), [Google (2)](https://www.aced.io/questions?company=google), [Microsoft](https://www.aced.io/questions?company=microsoft), [Samsung](https://www.aced.io/questions?company=samsung), [Palantir](https://www.aced.io/questions?company=palantir), [Barclays](https://www.aced.io/questions?company=barclays), [Meta](https://www.aced.io/questions?company=meta-facebook), and [Infosys](https://www.aced.io/questions?company=infosys). ## Question Given a binary tree, identify which nodes are leaf nodes, root nodes, or inner nodes. - **Leaf nodes:** A node with no children - **Root nodes:** A node with no parent - **Inner nodes:** A node with both children and parent nodes The input table is `tree_node_table`: | Column | Type | |---|---| | `id` | integer | | `p_id` | integer | `p_id` is the ID of the parent node. Return these columns: - `id` - `node_types`, with one of `Root`, `Inner`, or `Leaf` The solution editor supports SQLite. The solution and mock-interview tabs are locked, and the page includes an option to sign up to run code: [Sign up to run code](https://www.aced.io/signup?src=lesson). ## Interview experiences The page records **10 shared interview experiences** and shows “11 interviews,” with the last reported occurrence listed as 6 months ago. The experiences are user-submitted examples associated with the following roles and companies: 1. **Amazon — Software Engineer, Intern — 6 months ago**: “It went well and answered all questions. and did both leetcode questions asked one in each interview.” [Read the experience](https://www.aced.io/experiences/amazon-software-engineer-intern-interview-19b58a) 2. **Google — Software Engineer, Entry Level / L3 — 7 months ago**: “Pretty easy, just very long. For technical just need to do leetcode, no system design. Interviewers help you if you are stuck.” [Read the experience](https://www.aced.io/experiences/google-software-engineer-interview-0af9e4) 3. **Microsoft — Machine Learning Engineer, Entry Level / L3 — 7 months ago**: The contributor described smooth live-coding and system-architecture rounds, discussing API design, database strategy, and high availability for microservices. The behavioral portion felt rushed, and interviewers challenged assumptions with “what if” scenarios. [Read the experience](https://www.aced.io/experiences/microsoft-machine-learning-engineer-interview-f29ce8) 4. **Samsung — Software Engineer, Intern — 8 months ago**: “Smooth overall”; the recruiter communicated clearly, allowed enough time to schedule coding, and the coding interviewer set expectations well. [Read the experience](https://www.aced.io/experiences/samsung-software-engineer-intern-interview-62cb56) 5. **Google — Software Engineer, Mid Level / L4 — a year ago**: The contributor described an organized process and relevant, challenging technical interviews, while noting that time between stages made the process longer. [Read the experience](https://www.aced.io/experiences/google-software-engineer-interview-c471d4) 6. **Palantir — Software Engineer, Intern — a year ago**: The contributor described a more difficult-than-expected process involving LeetCode, a mini data project, and a sliding-window question. [Read the experience](https://www.aced.io/experiences/palantir-software-engineer-intern-interview-332d60) 7. **Amazon — Software Engineer, Intern — 2 years ago**: The contributor described a recruiter screen, online assessment, hiring-manager interview, and team interview, with technical LeetCode questions. [Read the experience](https://www.aced.io/experiences/amazon-software-engineer-intern-interview-bccbb0) 8. **Barclays — Software Engineer, Entry Level / L3 — 2 years ago**: The contributor described coding rounds with LC medium questions and system design, smoother behavioral rounds, and rapid increases in difficulty that made time management important. [Read the experience](https://www.aced.io/experiences/barclays-software-engineer-interview-31230a) 9. **Meta — Software Engineer, Intern — 2 years ago**: The contributor described a CodeSignal GCF assessment with four increasingly difficult sections, followed by two LeetCode-style medium questions in a 45-minute technical interview. [Read the experience](https://www.aced.io/experiences/meta-facebook-software-engineer-intern-interview-71076f) 10. **Infosys — Software Engineer, Entry Level / L3 — 2 years ago**: The contributor described a phone round followed by a technical interview, received an offer, and did not accept it. [Read the experience](https://www.aced.io/experiences/infosys-software-engineer-interview-9b8572) ## Related courses ### [Machine Learning Engineer Interview Prep](https://www.aced.io/courses/ml-engineer) ![Machine Learning Engineer Interview Prep](https://images.ctfassets.net/x78yjrjc11pq/6UfkHxUyLQVfDHSfLNQtWa/1be1539a65b4f6f15201f5b573c0a578/ML_Engineer_Interview_Prep_Course.jpeg?w=800&h=800&fm=webp&q=75) We cover mock interviews, frameworks, and advice from senior candidates for machine-learning roles at Meta, Google, Amazon, Apple, Microsoft, Nvidia, and other companies. Topics include ML system design, core concepts, coding, and behavioral interviews. ### [Software Engineering Interview Prep](https://www.aced.io/courses/software-engineering) ![Software Engineering Interview Prep](https://images.ctfassets.net/x78yjrjc11pq/4VkuYewBHUFIVUS5oJDW5h/02e833439b1289f25f38f13f81cbdca3/adobe_stock_optimized.jpeg?w=800&h=800&fm=webp&q=75) We cover mock interviews, frameworks, and advice from senior candidates for software-engineering roles at Google, Amazon, Microsoft, Meta, Apple, and other companies. Topics include data structures, algorithms, system design, people management, and behavioral interviews. ## Related Aced resources - [All questions](https://www.aced.io/questions) - [Coding questions](https://www.aced.io/questions?type=algorithms&filterBy=codeEditor&src=nav) - [SQL questions](https://www.aced.io/questions?type=sql&filterBy=codeEditor&src=nav) - [Practice](https://www.aced.io/practice?src=nav) - [Mock interviews and coaching](https://www.aced.io/coaching?category=mock_interviews&src=nav) - [Pricing](https://www.aced.io/upgrade?src=nav) --- [Read this page’s summary](https://www.aced.io/agents/api/public/v1/page-tldr?url=https%3A%2F%2Fwww.aced.io%2Fquestions%2F3957%2Ftree-node&trace=t_679ff9ab98f3) ## Ask a follow-up about this page Need a more specific answer? Ask the exact question you have. It returns a fresh, cited answer from Aced (formerly Exponent)’s knowledge base. No account or API key required. Open this URL with your own question, URL-encoded. 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