Preparation Strategy for Low Level Design (LLD) and Machine Coding

Introduction

• Presenter: Riddhi Datta
• Purpose: Share preparation strategy for low-level design and machine coding to crack startups and top product-based companies.
• Audience: Freshers, SD2, and above.

Preliminary Advice

• Disclaimer: Not an expert, still learning.
• Useful for: Both freshers and experienced software developers.

Key Concepts to Learn

Object-Oriented Principles (OOP)

• Essential for understanding low-level design.

Clean Coding

• Important for working in any company.
• Recommended book: Clean Code by Robert C. Martin.
• Learn solid patterns to improve code quality.

Design Patterns

• Singleton Design Pattern: Know especially for multi-threading if SD2 or above.
• Builder Pattern: Frequently asked in interviews.
• Factory and Abstract Factory: Essential patterns to understand.
• Adapter Pattern and Decorator Pattern: Important to know.
• Observer Pattern: Suggested to learn thoroughly.

Recommended Resources

• Head First Design Patterns book.
• YouTube channels: Sudoko, Gaurav Sen, various English and Hindi coding channels.
• UML diagrams: Learn basics, helpful in LLD interviews.

Types of Interviews

Classical LLD Interview

• Clarify requirements: Take 5-10 minutes.
• List down classes, entities, methods, and their interactions.
• Implement some methods or behaviors.

Machine Coding Round

• Implement code from scratch with passing test cases.
• Typically for startups and smaller companies.

Important Topics for LLD Interviews

• Parking Lot: Basic and common question.
• Snakes and Ladders: Prepare basic version; variations may be asked.
• Other Games: Chess, Ludo, Tic-Tac-Toe.
• BookMyShow: Prepare as both LLD and HLD question.
• ATM System: Commonly asked.
• Elevator System: Frequently asked, also in machine coding rounds.
• Vending Machine: Already covered in presenter's LLD playlist.
• Hotel Management System: Popular question.
• Carpooling/Rental: Uber, Ola, Zoomcar like systems.
• Miscellaneous: Typeahead, File system, Cricbuzz, Social media platforms like LinkedIn, Jira.

Machine Coding Specific Topics

• Splitwise: Frequently asked in tech companies.
• Rate Limiter: Important for companies like Atlassian.
• Advanced Topics: Messaging Queue, Distributed Cache. Typically for experienced developers (4+ years).
• Online Auction System: Often designed using Observer Design Pattern.

Preparation Tips

• Gather multiple resources: Books, YouTube videos, Medium articles.
• Understand there is no one correct solution: Be prepared to defend your design in an interview.
• Continuous learning and practice are key.

Final Recommendations

• Stay updated with new videos on the presenter's channel for continuous learning.
• Participate in coding contests like Code Rush X for practice.
• Self-study multiple resources and refine your design knowledge.