Segment Tree and Fenwick Tree (BIT) Interview Patterns
When Do You Need These? Segment trees and Fenwick trees (Binary Indexed Trees / BIT) solve range query problems efficiently. […]
Algorithms
Algorithms
Recursion Interview Patterns: Memoization, Tree Recursion, Classic Problems
The Recursion Mindset Recursion solves a problem by defining it in terms of a smaller version of the same problem.
System Design
System Design Interview: E-commerce and Inventory Management System
Core Components An e-commerce system handles product catalog, inventory tracking, shopping cart, order placement, payment processing, and fulfillment. Shopify processes
Algorithms
Divide and Conquer Interview Patterns: Merge Sort, Quick Select, Master Theorem
The Divide and Conquer Paradigm Divide and conquer solves problems by: (1) Divide — split the problem into smaller subproblems
Algorithms
Monotonic Stack Interview Patterns: Next Greater, Histograms, Stock Span
What Is a Monotonic Stack? A monotonic stack is a stack that maintains its elements in either monotonically increasing or
System Design
System Design Interview: Distributed Message Queue (Kafka / SQS)
Why Message Queues? A message queue decouples producers (services that generate events) from consumers (services that process them), enabling async
Algorithms
Union-Find (Disjoint Set Union) Interview Patterns
What Is Union-Find? Union-Find (also called Disjoint Set Union or DSU) is a data structure that efficiently tracks which elements
Algorithms
Binary Tree Interview Patterns: Traversal, DFS, BFS, and Classic Problems
Tree Traversal Fundamentals Binary tree problems appear in nearly every technical interview. The foundation is traversal order, which determines which
System Design
System Design Interview: Real-Time Chat System (WhatsApp / Slack)
Core Requirements A real-time chat system must: deliver messages in under 100ms end-to-end, support 1:1 and group chats, handle offline
System Design
System Design Interview: File Storage and Sync Service (Dropbox)
Designing a file storage and sync service like Dropbox combines chunked file storage, delta sync, conflict resolution, and offline-first architecture.
Algorithms
String DP Interview Patterns: LCS, Edit Distance, Palindrome DP
String dynamic programming problems — longest common subsequence, edit distance, palindromic subsequences — appear frequently in senior engineering interviews. These
System Design
System Design Interview: Twitter / Social Media Feed Architecture
Designing a social media feed like Twitter is one of the most comprehensive system design problems. The core challenge: how
System Design
System Design Interview: Hotel and Airbnb Booking System
Designing a hotel or home-sharing booking system like Airbnb is a comprehensive system design problem that combines availability calendars, concurrent
System Design
System Design Interview: Video Streaming Platform (Netflix/YouTube)
Designing a video streaming platform like Netflix or YouTube is one of the most comprehensive system design challenges, combining video
Algorithms
Dynamic Programming Knapsack Patterns: 0/1, Unbounded, Subset Sum
Knapsack problems are the most important dynamic programming pattern class. Mastering 0/1 knapsack, unbounded knapsack, and their variants (subset sum,