11 min read Shortest path problems appear in nearly every graph interview. The key skill is recognizing which algorithm applies to the given […] Read article
10 min read Range query problems appear frequently in competitive programming and technical interviews. Knowing which data structure to reach for – and Read article
9 min read Core Models: ACL, RBAC, ABAC, ReBAC Access control models define how permissions are assigned and evaluated. Each has different tradeoffs Read article
8 min read Monotonic Deque Pattern – Sliding Window Maximum LeetCode 239. Given an array and window size k, return the maximum in Read article
7 min read Core Probability Concepts Probability questions test your ability to reason about uncertainty and expected behavior. Three concepts appear repeatedly in Read article
4 min read Advanced Array Interview Patterns Mastering a handful of array techniques unlocks dozens of LeetCode problems. This guide covers the six Read article
4 min read System Design: A/B Testing Platform An A/B testing platform lets product teams run controlled experiments – assigning users to variants, Read article
5 min read Low-Level Design: Workflow Engine A workflow engine executes directed acyclic graphs (DAGs) of steps, handling parallelism, retries, and failure propagation. Read article
4 min read Core Entities Diff Computation Server-side diff using the Myers diff algorithm (also used by git). Output stored as unified diff Read article
5 min read Core Entities License Management Unlike physical books, digital copies can support multiple simultaneous loans up to a licensed limit. The Read article
4 min read Monotonic Stack Review A monotonic stack maintains elements in strictly increasing or decreasing order. Increasing monotonic stack: pop when the Read article
5 min read Thread Safety Fundamentals A race condition occurs when two threads read and write shared state concurrently without synchronization, producing non-deterministic Read article
7 min read Core Entities and Schema The recommendation engine centers on four entities. User: user_id, preferences JSONB, created_at. Item: item_id, category, features Read article
6 min read Reverse Linked List: Iterative, Recursive, and K-Groups Reversing a linked list (LC 206) is the foundational operation. Iterative: maintain prev=None, Read article
5 min read Sliding Window Maximum – Monotonic Deque (LC 239) O(n) solution using a monotonic decreasing deque storing indices. Each element is Read article
