Linkedin Interview Questions
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Design a malicious-URL checking service using an isMalicious API
Design a backend service that determines whether a given URL is malicious. You have access to an external dependency: - isMalicious(url) -> bool (blac...
Design a metrics platform without alerting
Design a metrics platform (like a simplified Prometheus/Datadog metrics product) that supports collecting, storing, querying, and visualizing metrics....
Find dictionary words matching a phone digit string
You are given: - A digit string digits consisting of characters '2'–'9'. - A list of lowercase words words (dictionary). Use the classic phone keypad ...
Compute graph distance and impacted services
Part A — Graph shortest distance (BFS) You are given an interface representing a node in an unweighted graph: `java interface Candidate { String id(...
Merge two N-ary trees by key rules
You are given two N-ary trees A and B. Each node has: - key (string): unique among siblings (i.e., within a node’s children list, no two children shar...
Design a scalable key-value store
System Design: Distributed Key-Value Store Design a distributed key-value (KV) storage service for a large-scale backend system. The service should ex...
Implement an LRU cache with follow-ups
Coding: Implement an LRU Cache and discuss concurrency Design and implement an in-memory Least Recently Used (LRU) cache data structure. The cache sho...
Design a company-wide monitoring system
You are asked to design a monitoring system used company-wide. Goals - Collect and query telemetry for many services/hosts - Support alerting and dash...
Design an in-memory key-value store using maps
Design a low-level key-value store library (like an embedded storage engine) under an interview constraint: you may use only map/dictionary-like data ...
Find the k-th largest element in an array
Given an integer array nums and an integer k, return the k-th largest element in the array. Notes: - The k-th largest element is the element that woul...
Count connected land components in a grid
You are given a 2D grid of characters where: - '1' represents land - '0' represents water A group of land cells forms an island if they are connected ...
Design a Top-K search words service
Scenario Design a service that tracks user search queries and returns the Top-K most searched words/queries. Requirements Functional - API to record a...
Validate parentheses with one or three bracket types
Problem Given a string s consisting only of bracket characters, determine whether it is valid. A string is valid if: - Every opening bracket has a cor...
Design scalable job scheduler and query dashboard
Design a scalable, fault-tolerant job scheduling system. The system should allow clients to schedule background jobs (for example, sending emails or r...
Compare heap and stack memory
Compare heap and stack memory. Explain how each is allocated and freed, typical lifetimes of data stored there, access patterns and performance charac...
Explain a past project and critique a prior team
Interview prompts 1. Project deep dive: Pick a past project you worked on and walk through it end-to-end. Be ready to use a whiteboard to explain arch...
Design an exception monitoring system with top‑K
System Design: Exception Monitoring with Top-K Design an exception monitoring system for a microservices environment. Core requirements - Services emi...
LinkedIn Product Case Opportunity Sizing
Case: Segment users, size sales professionals, and predict adoption for an email-promoted product Context: You are interviewing for a Data Scientist r...
Group words that map to same phone digits
Problem On a classic phone keypad (T9), letters map to digits: - 2: ABC, 3: DEF, 4: GHI, 5: JKL, - 6: MNO, 7: PQRS, 8: TUV, 9: WXYZ Given a list of lo...
Compute total covered interval length
Given a list of integer intervals [l, r) (half-open), compute the total length covered by at least one interval. Intervals may overlap or be nested. R...