LinkedIn Interview Questions
Practice 147 real LinkedIn interview questions for 2026. Covers all top categories — Coding & Algorithms, System Design, Analytics & Experimentation, Data Manipulation (SQL/Python), and Behavioral & Leadership — across Software Engineer, Data Scientist, Machine Learning Engineer, and Data Engineer roles. Real questions from actual interviews with detailed solutions; this collection is designed for focused interview preparation that prioritizes coding and scale-first problem solving alongside rigorous metrics thinking. Expect LinkedIn interviews to evaluate production-ready tradeoffs, clear metricization of ranking and relevance, and the ability to diagnose live-traffic regressions. For Software Engineer candidates, recurring themes include constant-time randomized data structures and frequency-weighted sampling, Top-K ranking service design and distributed-scaling considerations, plus classic array/string and stack-with-max algorithmic problems. Data Scientists should be ready for model fundamentals and optimization (logistic regression, backprop, Adam), causal and experimentation diagnostics for feed/homepage drops, and sampling/variance concerns in ranking metrics. Machine Learning Engineers will see recommendation and skills-inference system design, clustering convergence and probabilistic sampling questions, and production alerting/spike-detection. Data Engineers encounter efficient data-structure implementations tied to measurable production impact.
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Merge Keyed N-Ary Trees
Merge Keyed N-Ary Trees An N-ary tree node contains a unique string key among its siblings and a list of children. Implement merge_trees(a, b) for two...
Design a CI/CD Task Scheduler
Design a CI/CD Task Scheduler Design the scheduling core of a continuous-integration and continuous-delivery system. A pipeline is a directed acyclic ...
Design a Calendar System
This question evaluates a candidate's ability to design a large-scale calendar backend, covering data modeling for events, recurrence, invitations, an...
Review a Web Application Architecture
You are given a high-level architecture diagram for a web application: Client/Web App -> DNS -> Load Balancer -> Application Service -> Database The a...
Explain Logistic Regression, Backprop, and Adam
Walk through the mathematical foundations that connect logistic regression to modern deep-learning training. The interviewer expects you to write the ...
Scale a Distributed Randomized Multiset
After designing the randomized multiset on a single machine, explain how you would scale it across multiple servers. The distributed system should sup...
Solve common string and subarray problems
You are given three coding tasks: 1) Reverse a string - Input: a string s. - Output: the string with characters in reverse order. 2) Maximum sum of a ...
Longest Run of Ones After One Flip
This question tests a candidate's ability to solve a sliding window problem involving binary arrays, extending the basic "maximum consecutive ones" pa...
Sample uniformly from a circle’s area
How would you generate a point (x, y) uniformly at random from the area of a circle of radius R centered at the origin? - Explain why naive choices (e...
Answer practical ML foundations questions
In an ML interview, you are asked a series of practical ML foundation questions: 1) Model outputs probabilities. When do you need probability calibrat...
Design a Top-K Ranking Service
This question evaluates a candidate's ability to design scalable, real-time Top-K ranking services, testing competencies in distributed systems, strea...
Analyze member video posting behavior by country
Question You are given two tables describing LinkedIn members and the videos they upload. Write SQL (and optionally Python where noted) to answer the ...
Choose single queue vs multiple queues
This question evaluates understanding of queueing theory, stochastic modeling of wait times, variability analysis, and the ability to state modeling a...
Explain variance reduction in random forests
This question evaluates understanding of variance reduction in ensemble methods, the impact of inter-tree correlation on averaged predictors, and the ...
Design a Global Calendar Service
Design a calendar system for users in multiple time zones. The system should support: - creating, updating, deleting, and viewing calendar events - on...
Discuss Projects and Tradeoffs
You are asked to do a deep dive on two past software projects. For each project, explain: 1. The business or engineering problem. 2. Your exact role, ...
Plan and lead a large recommendation project
You are given a recommendation design problem, but the interviewer focuses on leadership and execution rather than detailed modeling. Explain how you ...
Handle imbalance, sampling, and overfitting
This question evaluates a data scientist's proficiency in machine learning topics including handling class imbalance, selecting and interpreting evalu...
Design a malicious-URL checking service using an isMalicious API
This question evaluates system design competencies such as scalable API design, caching and cache invalidation strategies, rate limiting and backpress...
Handle Issues and Onboard Teammates
The manager and communication rounds focused on two prompts: 1. Tell me about a time you handled a cross-functional issue, operational incident, or di...