6 min read What is a Distributed Configuration Service? A configuration service manages application settings, feature flags, and operational parameters across a distributed […] Read article
6 min read Essential Bit Operations x & y # AND: both bits must be 1 x | y # OR: at least Read article
6 min read Requirements Producers enqueue tasks; workers process them asynchronously At-least-once delivery: tasks must not be lost on worker crash Retry with Read article
6 min read What is A/B Testing? A/B testing (controlled experimentation) randomly assigns users to experimental variants and measures which variant produces better Read article
6 min read What is Topological Sort? A topological ordering of a directed acyclic graph (DAG) is a linear ordering of vertices such Read article
6 min read Requirements Detect fraudulent transactions in real time (<200ms per transaction decision) Flag suspicious user behavior: account takeover, card testing, synthetic Read article
6 min read Requirements Ingest billions of events per day (page views, clicks, transactions, errors) Support real-time dashboards with <10 second lag Support Read article
6 min read Core Idea A stack (LIFO) is the right tool when the most recently seen element determines the action for the Read article
6 min read Requirements Record every ad click event (ad_id, user_id, timestamp, ip, device_type) Query click counts per ad for any time range Read article
6 min read What an API Gateway Does An API gateway is the single entry point for all client requests to a microservices Read article
6 min read The Pattern Divide and conquer splits a problem into independent subproblems, solves each recursively, and combines the results. Three steps: Read article
5 min read Requirements Update a player score in real time Query the global top-100 leaderboard Query a player’s exact rank among all Read article
6 min read Why Distributed Locks? In a distributed system, multiple servers run the same code concurrently. A distributed lock ensures only one Read article
6 min read Requirements Users can browse events, select seats from a seat map, reserve seats, and complete payment Prevent double-booking: no two Read article
6 min read GCD and LCM Euclidean algorithm: gcd(a,b) = gcd(b, a%b), base case gcd(a,0) = a. Time O(log min(a,b)). LCM: lcm(a,b) = Read article
