String Interview Patterns
9 min read Strings appear in roughly 25-30% of coding interviews. Unlike arrays or trees, string problems have a concentrated set of patterns […] Read article
Algorithms, Coding Interview Questions, String Manipulation
System Design
Search Autocomplete System Low-Level Design
9 min read Search autocomplete is one of the most latency-sensitive features in any product. Users expect suggestions within 100ms of each keystroke. Read article
Algorithms, Coding Interview Questions
Interval Interview Patterns
7 min read Interval problems are a reliable interview topic at every level. The core patterns repeat across dozens of problems – learn Read article
System Design
Rate Limiter System Low-Level Design
8 min read Rate limiting is a core system design topic. This guide covers every major algorithm, their trade-offs, and Redis implementation patterns Read article
Algorithms, Coding Interview Questions, Trie
Trie Interview Patterns
9 min read Trie (prefix tree) problems appear frequently in coding interviews. This guide covers the core patterns with Python implementations you can Read article
Algorithms, Coding Interview Questions, Graphs, Shortest Path
Graph Shortest Path Interview Patterns
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
System Design
User Authentication System Low-Level Design
11 min read Authentication is one of the most common low-level design questions in system design interviews, and one of the most commonly Read article
Algorithms, Coding Interview Questions, Data Structures
Range Query Interview Patterns
10 min read Range query problems appear frequently in competitive programming and technical interviews. Knowing which data structure to reach for – and Read article
Algorithms, Coding Interview Questions, Monotonic Queue, Queue
Queue and Deque Interview Patterns
8 min read Monotonic Deque Pattern – Sliding Window Maximum LeetCode 239. Given an array and window size k, return the maximum in Read article
System Design
Access Control System Low-Level Design
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
Algorithms, Coding Interview Questions, Math
Probability and Statistics Interview Patterns
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
System Design
Low-Level Design: Workflow Engine – DAG Execution, Step Retry, and State Persistence (2025)
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
System Design
System Design: A/B Testing Platform – Experiment Management, Assignment, and Statistical Analysis (2025)
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
Algorithms
Advanced Array Interview Patterns: Prefix Sum, Difference Array, and Kadane’s Algorithm (2025)
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
System Design
Low-Level Design: Digital Library System – Catalog, Borrowing, Reservations, and DRM (2025)
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