Beyond basic DFS traversal, advanced DFS patterns solve graph structure problems: finding cycles, identifying critical nodes and edges, and decomposing […]
Reddit is the “front page of the internet” with 50+ million daily active users across 100,000+ active communities (subreddits). Designing
Google Drive serves 1+ billion users storing documents, spreadsheets, photos, and files with real-time collaboration, sharing, and cross-device sync. While
Beyond basic BFS/DFS, advanced graph algorithms solve optimization problems: finding the cheapest path with constraints, detecting negative cycles, computing all-pairs
WhatsApp Status (stories) lets 2+ billion users share photos, videos, and text that disappear after 24 hours. Designing an ephemeral
System design interviews have a high failure rate — not because the problems are impossible, but because candidates make predictable
Airbnb connects 4+ million hosts with 150+ million guests across 220+ countries. Designing an accommodation platform tests your understanding of
GitHub hosts 200+ million repositories for 100+ million developers. Designing a code hosting platform tests your understanding of distributed version
Zoom handles 300+ million daily meeting participants with real-time audio and video. Designing a video conferencing system tests your understanding
Back-of-envelope estimation is expected in every system design interview. Having key numbers memorized — latency, throughput, storage sizes, and powers
Pinterest is a visual discovery platform with 450+ million monthly active users who save, organize, and discover ideas through images
Dropbox syncs files across devices for 700+ million users, handling billions of file operations daily. Designing a file storage and
Math-based problems appear in approximately 10% of coding interviews and are often considered the hardest category because the solutions require
Tinder processes 2+ billion swipes per day across 190+ countries, matching users based on location, preferences, and recommendation algorithms. Designing
Spotify serves 600+ million users across 180+ markets, streaming over 100 million tracks with sub-second start times. Designing a music
