Fine calculation in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of a fine calculation system?

To automatically compute penalties or fees based on predefined rules when certain conditions are met, such as late returns or violations.

beginner

Name two common inputs required for calculating a fine.

1. The date or time when the violation occurred or item was due.<br>2. The current date or return date to calculate delay duration.

intermediate

Why is it important to design fine calculation as a separate module in a system?

Separating fine calculation allows easy updates to rules without affecting other parts, improves maintainability, and supports reuse across different services.

intermediate

What is a common strategy to handle different fine rules for various violation types?

Use a rule engine or strategy pattern to apply different fine calculation logic based on violation type dynamically.

advanced

How can scalability be ensured in a fine calculation system?

By designing stateless services, caching frequent calculations, and using asynchronous processing for bulk fine computations.

Which input is essential for calculating a late return fine?

A Return date and due date

B User's name

C Item color

D User's address

The return date and due date are needed to calculate how late the return is.

What design pattern helps apply different fine rules based on violation type?

A Observer pattern

B Singleton pattern

C Strategy pattern

D Factory pattern

Strategy pattern allows selecting different algorithms (fine rules) at runtime.

Why should fine calculation logic be separated from other system parts?

A To slow down processing

B To increase system complexity

C To reduce user interface features

D To improve maintainability and flexibility

Separation improves maintainability and allows easier updates.

Which approach helps handle high volume fine calculations efficiently?

A Synchronous blocking

B Asynchronous processing

C Manual calculation

D Ignoring scalability

Asynchronous processing allows handling many calculations without blocking.

What is a typical output of a fine calculation system?

A Calculated penalty amount

B User password

C System logs only

D User profile picture

The main output is the penalty or fine amount to be charged.

Explain how you would design a fine calculation module for a library system.

Think about inputs, rules, modularity, and performance.

Describe strategies to make fine calculation flexible for future rule changes.

Focus on design patterns and configuration.