5 min read Core Entities Product: product_id, name, description, type (SAAS, MEDIA, PHYSICAL). Plan: plan_id, product_id, name, billing_period (MONTHLY, QUARTERLY, ANNUAL), price, currency, […] Read article
6 min read Graph Algorithm Selection Guide Choosing the right graph algorithm is the first step in any graph interview question. BFS: unweighted Read article
5 min read Interval Problem Patterns Interval problems form a distinct category: they involve ranges [start, end] and typically require detecting overlaps, merging, Read article
5 min read Core Entities Provider: provider_id, user_id, name, type (DOCTOR, CONSULTANT, TRAINER, THERAPIST), timezone, bio, photo_url, is_active. Service: service_id, provider_id, name, duration_minutes, Read article
6 min read Requirements A drone delivery platform dispatches autonomous drones to deliver packages from warehouses or stores to customer addresses. Core challenges: Read article
5 min read Grid DP Fundamentals Grid DP problems define a 2D state space where dp[i][j] represents some optimum property at cell (i, Read article
6 min read Core Entities Book: book_id, isbn, title, authors (array), publisher, published_year, genre, language, description, cover_url. BookCopy: copy_id, book_id, library_id, condition (NEW, Read article
6 min read Requirements An IoT data platform ingests telemetry from millions of connected devices — sensors, smart meters, industrial equipment, wearables — Read article
6 min read Tree Pattern Overview Tree problems test recursive thinking and the ability to combine top-down and bottom-up information. Most tree problems Read article
6 min read Core Entities ParkingLot: lot_id, name, address, total_floors, total_spaces, open_time, close_time, timezone. ParkingFloor: floor_id, lot_id, floor_number, total_spaces, available_spaces. ParkingSpace: space_id, floor_id, Read article
6 min read Binary Search Beyond Sorted Arrays Binary search is not just for sorted arrays. The generalized binary search applies to any Read article
4 min read Core Entities Member: member_id, user_id, first_name, last_name, email, phone, photo_url, join_date, status (ACTIVE, SUSPENDED, CANCELLED, FROZEN), emergency_contact. MembershipPlan: plan_id, name Read article
5 min read Requirements An analytics dashboard lets users visualize business metrics: revenue over time, active users, conversion rates, funnel analysis, A/B test Read article
5 min read Core Entities Vehicle: vehicle_id, vin (unique), make, model, year, type (SEDAN, VAN, TRUCK, ELECTRIC), status (AVAILABLE, ASSIGNED, IN_MAINTENANCE, OUT_OF_SERVICE), current_driver_id, Read article
6 min read What is a CDN and Why Does It Matter? A CDN is a geographically distributed network of edge servers that Read article
