Trie and String Algorithm Interview Patterns
Tries (prefix trees) and string algorithms appear in autocomplete, spell checking, IP routing, and competitive programming. Mastering trie construction and […]
Algorithms
System Design
System Design Interview: Recommendation Engine at Scale
Recommendation systems power product discovery at Netflix, Spotify, Amazon, and LinkedIn. Designing one at scale involves a multi-stage architecture that
System Design
System Design Interview: Distributed File System (GFS/HDFS/S3)
Designing a distributed file system (DFS) like HDFS, Google File System, or Amazon S3 is a classic system design interview
Algorithms
Heap and Priority Queue Interview Patterns
When to Use a Heap A heap (priority queue) is the right data structure when you need: the minimum or
System Design
System Design Interview: Ride-Sharing Dispatch System (Uber/Lyft)
Dispatch System Requirements A ride-sharing dispatch system matches riders with nearby available drivers in real time. Core requirements: find available
Algorithms
Dynamic Programming Patterns: Tree DP, Digit DP, and Bitmask DP
Beyond Basic DP Once you’ve mastered 1D/2D tabulation and memoization (Fibonacci, LCS, Knapsack, Coin Change), advanced interview problems require recognizing
System Design
System Design Interview: WebRTC and Real-Time Video Architecture
WebRTC Architecture Overview WebRTC (Web Real-Time Communication) is an open standard that enables peer-to-peer audio and video in browsers and
System Design
System Design Interview: Social Graph and Friend Recommendations
Social Graph Requirements A social graph stores relationships between users (friendships, follows, connections) and enables graph queries: friends of friends,
System Design
System Design Interview: Financial Exchange and Matching Engine
Exchange Architecture Overview A financial exchange matches buy and sell orders — a buyer willing to pay $100 for AAPL
System Design
System Design Interview: Notification System at Scale
Notification System Requirements A notification system routes messages from producers (application events) to consumers (users) via multiple channels: push notifications
System Design
System Design Interview: Job Scheduler and Task Queue
Why Task Queues? Task queues decouple work production from work execution. Instead of processing a long-running task synchronously (blocking the
System Design
System Design Interview: Database Indexing and Query Optimization
Why Indexing Matters Without an index, a SELECT with a WHERE clause requires a sequential scan — reading every row
System Design
System Design Interview: Real-Time Collaborative Editing (Google Docs)
The Collaboration Problem Real-time collaborative editing lets multiple users edit the same document simultaneously with all changes visible to all
System Design
System Design Interview: API Rate Limiting and Throttling
Why Rate Limiting? Rate limiting protects services from overload, abuse, and cost explosions. Without it: a single misbehaving client can
System Design
System Design Interview: Log Aggregation and Observability Pipeline
Why Log Aggregation? With hundreds of microservices each running multiple replicas, logs are scattered across thousands of containers. Without centralized