Strategy pattern in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Strategy pattern in software design?

The Strategy pattern is a design approach that lets you choose an algorithm's behavior at runtime. It defines a family of algorithms, encapsulates each one, and makes them interchangeable without changing the code that uses them.

beginner

How does the Strategy pattern help in system design?

It helps by separating the algorithm from the client using it. This makes the system flexible and easier to extend or modify without changing existing code, reducing bugs and improving maintainability.

intermediate

In the Strategy pattern, what roles do the Context and Strategy play?

The Context is the object that uses a Strategy to perform a task. The Strategy is an interface or abstract class that defines the algorithm. Concrete Strategies implement this interface with different behaviors.

beginner

Give a real-life example of the Strategy pattern.

Think of a navigation app that can choose different routes: fastest, shortest, or scenic. Each route calculation is a Strategy. The app (Context) picks the Strategy based on user choice without changing its core logic.

intermediate

What is a key advantage of using the Strategy pattern over conditional statements?

It avoids complex conditional logic by encapsulating each algorithm separately. This makes the code cleaner, easier to read, and simpler to add new algorithms without modifying existing code.

What does the Strategy pattern primarily allow you to do?

A Enforce a single instance of a class

B Create multiple instances of a class

C Change an algorithm's behavior at runtime

D Hide the internal details of an object

The Strategy pattern lets you select and change algorithms dynamically during program execution.

In the Strategy pattern, what is the role of the Context?

A Defines the algorithm interface

B Uses a Strategy to perform a task

C Manages object creation

D Implements a specific algorithm

The Context holds a reference to a Strategy and uses it to execute the algorithm.

Which of the following is NOT a benefit of the Strategy pattern?

A Improves code flexibility

B Reduces conditional statements

C Makes adding new algorithms easier

D Enforces a fixed algorithm at compile time

The Strategy pattern allows changing algorithms at runtime, not fixing them at compile time.

How does the Strategy pattern relate to the Open/Closed Principle?

A It supports it by allowing new strategies without changing existing code

B It violates it by modifying existing code

C It ignores it completely

D It enforces code duplication

The pattern supports the Open/Closed Principle by enabling new algorithms without altering existing code.

Which design pattern is often confused with Strategy but focuses on object creation?

A Factory pattern

B Observer pattern

C Decorator pattern

D Singleton pattern

The Factory pattern deals with creating objects, while Strategy deals with interchangeable algorithms.

Explain the Strategy pattern and how it improves software design.

Think about how you can swap behaviors without changing the main code.

Describe a real-world scenario where the Strategy pattern can be applied and why it is useful there.

Consider situations where you choose different ways to do the same task.