Top 10 Software Engineering Interview Questions
Master the fundamentals of software engineering interviews at European tech companies. Covers algorithms, system design, and coding challenges used by companies like Spotify, Zalando, and SAP.
Explain the difference between a stack and a queue. When would you use each?
Expert Tip: Use real-world analogies like browser back button (stack) and printer queue.
How would you design a URL shortener like bit.ly?
Expert Tip: Discuss hashing, base62 encoding, database choice, and scalability.
Implement an LRU cache with O(1) get and put operations.
Expert Tip: Use a doubly-linked list + hashmap combination.
Design a rate limiter for a distributed system.
Expert Tip: Cover token bucket, sliding window, and Redis-based approaches.
What is the CAP theorem? How does it affect system design?
Expert Tip: Give practical examples: DynamoDB (AP), PostgreSQL (CP).
Explain event-driven architecture. When is it appropriate?
Expert Tip: Reference Kafka/RabbitMQ and discuss eventual consistency.
How would you optimize a SQL query that scans millions of rows?
Expert Tip: Indexing, query plan analysis, partitioning, materialized views.
Reverse a linked list iteratively and recursively.
Expert Tip: Know both approaches cold. Discuss time/space complexity.
Design a notification system for a social media platform.
Expert Tip: Cover push vs pull, WebSockets, queuing, and batching.
What are SOLID principles? Provide examples for each.
Expert Tip: Use code examples — European interviewers appreciate practical demos.
Recommended Resources
Cracking the Coding Interview
The classic interview prep book covering all fundamental topics.
System Design Interview by Alex Xu
Step-by-step framework for system design questions.
LeetCode / HackerRank
Practice coding challenges daily — focus on medium difficulty.