Graph Interview Patterns: A Complete Guide (2025)
Graph problems appear in every serious technical interview. They cover a wide range of difficulty — from simple BFS/DFS traversal […]
Algorithms
System Design
System Design Interview: Music Streaming Service (Spotify)
Spotify serves 600M users, 100M tracks, and 9M daily podcast episodes. Designing a music streaming service covers audio delivery, catalog
Algorithms
Trie Interview Patterns: A Complete Guide (2025)
A trie (prefix tree) is a tree where each node represents a character and the path from root to a
System Design
System Design Interview: Distributed Task Queue (Celery / SQS / Sidekiq)
A distributed task queue decouples work production from work execution. Instead of processing a request synchronously (blocking the HTTP response),
Algorithms
Backtracking Interview Patterns: A Complete Guide (2025)
Backtracking is systematic trial and error — explore a decision tree, and when you reach a dead end, undo the
System Design
System Design Interview: Microservices Architecture Patterns
Monolith vs Microservices A monolith deploys all application functionality as one unit. Simple to develop initially, but becomes harder to
Algorithms
Two Pointers Interview Patterns: A Complete Guide (2025)
Two Pointers Fundamentals Two pointers use two indices traversing an array or string to solve problems in O(n) that would
System Design
System Design Interview: Data Pipeline and ETL System (Airflow / Spark)
What Is a Data Pipeline? A data pipeline moves and transforms data from source systems (databases, APIs, event streams) to
System Design
System Design Interview: Configuration Management Service (etcd / Consul)
What Is a Configuration Management Service? A configuration management service stores application configuration (database connection strings, feature toggle values, service
Algorithms
Stack and Queue Interview Patterns (2025)
Stack and Queue Fundamentals A stack is LIFO (last-in, first-out): push adds to the top, pop removes from the top.
System Design
System Design Interview: Monitoring and Observability Platform (Datadog)
The Three Pillars of Observability Observability is the ability to understand the internal state of a system from its external
System Design
System Design Interview: Distributed Lock Manager (Redis / Zookeeper)
Why Distributed Locks Are Needed In a distributed system, multiple instances of a service may run concurrently. When these instances
Algorithms
Sliding Window Interview Patterns: A Complete Guide (2025)
The Sliding Window Technique The sliding window technique optimizes brute-force O(n^2) or O(n^3) problems to O(n) by maintaining a window
System Design
System Design Interview: Feature Flag System (LaunchDarkly)
What Are Feature Flags? Feature flags (also called feature toggles or feature gates) decouple code deployment from feature release. A
System Design
System Design Interview: Content Moderation System (Instagram / YouTube)
Why Content Moderation Is a Hard Systems Problem A platform with 500 million daily active users generates billions of pieces