4 Most Common Design Patterns for Low Level Design Interviews

The 4 most common design patterns used in LLD interviews are:

Strategy pattern,

Observer pattern,

Factory pattern and

Singleton Pattern. If you ask, which is the most common or most po

The 4 most common design patterns used in LLD interviews are:

Strategy pattern,

Observer pattern,

Factory pattern and

Singleton Pattern. If you ask, which is the most common or most popular design pattern then answer will be

Singleton pattern. But it has a catch, which we will come back to, later in this article. Let's go through these design patterns and their use cases from LLD interviews one by one. Also for testing any LLD question during interviews you will create a Controller class which will have all required methods and object of that controller class will be used for testing the system you designed. That's Facade design pattern. ---------------------------------------------------- PS: You can ask me any low level design related questions on r/LowLevelDesign I also take LLD mock interviews: <a href="https://topmate.io/prashant_priyadarshi*

Design a parking lot: Strategy pattern can be used to implement the different strategies for parking the vehicle. <a href="https://codezym.com/question/7*

Design a Game of Chess: Strategy pattern can be used to implement the different moves for different chess pieces, like straight move (made by rook), diagonal move (bishop), 2+1 move (Knight) etc. <a href="https://codezym.com/question/8*

Design a Customer Issue Resolution System: Implement the different ways to assign an agent to a given issue, depending on various factors. <a href="https://codezym.com/question/3*

Design an e-commerce website: To implement different ways to order list of items on search page. e.g. by price, rating or popularity. Using strategy pattern enables us to add new strategies in future without changing code in existing strategies. Hence code becomes easy to extend. watch below YouTube video for understanding strategy pattern better. <a href="https://youtu.be/R_AadNfw0k8*

Design a Movie ticket booking system like BookMyShow: Whenever a new show is added for displaying a movie in a cinema hall, then it needs to be updated to class which maintains list of cinemas running a particular movie in a city or to class which maintains list of shows for a particular movie in a cinema hall. This can also be solved using observer pattern. <a href="https://codezym.com/question/10*

Design a Game of Chess: There are 32 different chess pieces like 2 kings (1 white, 1 black),16 pawns (8 black, 8 white), 4 knights (2 white, 2 black) etc. But all chess pieces have the same move() method. Hence, we use ChessPiece factory here to create all the different pieces. <a href="https://codezym.com/question/8.