Object-Oriented Design Principles - SOLID

Who gets asked Low Level Design questions? Almost every leading payer (product company) has LLD rounds now, even freshers sometimes have LLD rounds. Companies: Amazon, Microsoft, Google & leading startups.

What is Low Level Design? Low Level Design (LLD), also known as Object Oriented Design (OOD), is a detailed description of all components, configurations, and processes of the software. Low Level Design focuses on the class-level design of a software and clean, fast, readable, maintainable, and extensible code.

The Expectations of LLD interviews

An LLD Interview evaluates your skill on creating modular, flexible, maintainable and reusable software, by applying Object-oriented Design Principles and Design Patterns.

LLD questions like,

Design a Parking Lot,

Design a Tic-tac-toe Game,

Design a Ticketing System


in the class-level, are intentionally unstructured and open-ended and they don't have a standard answer.

How to Prepare for the LLD Interview

  1. Learn an object-oriented language ( C++ / Java / Python or C# )

  2. Study about the SOLID and other Object Oriented Principles

  3. Learn all the common Design Patterns and their applications

  4. Explore some open-source projects and try to understand the best practices

  5. Practice common LLD interview questions

LLD Principles

The object-oriented design principles are also called SOLID.

The main goal of these principles is to make software resilient to changes and easy to extend and maintain...

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