interview-prep

HLD:

Theory Sources:

• Jordan Videos for theory - https://www.youtube.com/watch?v=crPoHnhkjFE&list=PLjTveVh7FakLdTmm42TMxbN8PvVn5g4KJ&index=53&ab_channel=Jordanhasnolife

Question Sources:

• Jordan - new series is coming up though - https://www.youtube.com/watch?v=J-5JozlYIqI&list=PLjTveVh7FakJOoY6GPZGWHHl4shhDT8iV&index=20&ab_channel=Jordanhasnolife
• https://www.hellointerview.com/learn/system-design/problem-breakdowns/ticketmaster
• https://bytebytego.com/courses/system-design-interview/real-time-gaming-leaderboard

Additional Resources:

• https://github.com/donnemartin/system-design-primer/tree/master

LLD

Tips:

• https://leetcode.com/discuss/post/7024347/help-required-for-lld-by-anonymous_user-gehe/

Theory:

• Design Principles: https://github.com/prateek27/design-patterns-java

Questionresources

• https://github.com/ycwkatie/OOD-Object-Oriented-Design?tab=readme-ov-file -> has questions and handwritten solutions
• https://github.com/ashishps1/awesome-low-level-design/blob/main/problems -> questions+diagrams+solutions+code

Not useful yet, but to explore

• Gaurav Sen LLD playlist - https://www.youtube.com/watch?v=I-iZbOVXwxg&list=PLMCXHnjXnTnvQVh7WsgZ8SurU1O2v_UM7&index=3&ab_channel=GauravSen
• Soumyajit Bhattacharayay LLD questions playlist - https://www.youtube.com/watch?v=7LaKmNfMCAo&list=PL12BCqE-Lp650Cg6FZW7SoZwN8Rw1WJI7&index=5&ab_channel=SoumyajitBhattacharyay -> not very useful

Tips

• Interface should include methods and NOT variables. So, if you want to have an interface with some variables, include its getters/setters in the interface:
• Use classes for entities because you need fields/attributes, and possible methods later. Use interfaces for service layers or when you want to allow multiple implementations (e.g., BooksRepo, UserDao).

interface FileSystemNode { 
    String getName();
    String getPath();
    boolean isDirectory();
    // than having propeties name, path, isDirectory
}

• How to Generalize the Decision of where mappings should be stored? Mappings are generally stored in the DAO/repository of the entity being mapped TO, especially if that's your main access pattern. Seller-to-products: ProductDao, since products are the "leaf" objects and may be queried by seller often. User-to-Order, Product-to-order: OrderDao, since orders are typically the main entry point for these queries.