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, […]
Interval Problem Patterns Interval problems form a distinct category: they involve ranges [start, end] and typically require detecting overlaps, merging,
Graph Algorithm Selection Guide Choosing the right graph algorithm is the first step in any graph interview question. BFS: unweighted
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,
Grid DP Fundamentals Grid DP problems define a 2D state space where dp[i][j] represents some optimum property at cell (i,
Requirements A drone delivery platform dispatches autonomous drones to deliver packages from warehouses or stores to customer addresses. Core challenges:
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,
Tree Pattern Overview Tree problems test recursive thinking and the ability to combine top-down and bottom-up information. Most tree problems
Requirements An IoT data platform ingests telemetry from millions of connected devices — sensors, smart meters, industrial equipment, wearables —
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
Binary Search Beyond Sorted Arrays Binary search is not just for sorted arrays. The generalized binary search applies to any
Requirements An analytics dashboard lets users visualize business metrics: revenue over time, active users, conversion rates, funnel analysis, A/B test
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,
Why Linked Lists in 2025? Linked list problems test pointer manipulation, in-place operations with O(1) space, and the two-pointer (fast/slow)
What is a CDN and Why Does It Matter? A CDN is a geographically distributed network of edge servers that
