Requirements and use cases in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Functional vs Non-Functional Requirements

Which of the following is an example of a non-functional requirement in a system design?

A The system must allow users to reset their passwords via email.

B The system should support login using username and password.

C The system must store user profiles with name and email address.

D The system should respond to user requests within 2 seconds.

💡 Hint

Non-functional requirements describe how the system performs rather than what it does.

Option D describes a performance constraint, which is a non-functional requirement. The others describe specific features (functional requirements).

❓ Architecture

intermediate

Use Case Diagram Interpretation

Given a use case diagram with actors: User, Admin; and use cases: Login, Manage Users, View Reports, which use case is typically exclusive to the Admin actor?

A Manage Users

B All use cases are for both actors

C View Reports

D Login

💡 Hint

Think about which actions require higher privileges.

Managing users usually requires admin privileges, so only Admin can perform 'Manage Users'. Login and View Reports can be common to both.

❓ scaling

advanced

Estimating System Load from Use Cases

A system has 10,000 daily active users. The use case 'Upload Photo' is used by 20% of users daily, each uploading 3 photos on average. What is the estimated number of photo uploads per day?

A 6,000 uploads

B 30,000 uploads

C 200,000 uploads

D 600 uploads

💡 Hint

Calculate the number of users performing the action and multiply by average uploads.

20% of 10,000 users = 2,000 users. Each uploads 3 photos, so 2,000 * 3 = 6,000 uploads (Option A).

❓ tradeoff

advanced

Tradeoff Between Requirements and System Complexity

Adding a requirement for real-time notifications increases system complexity. Which is the best tradeoff approach?

A Ignore the requirement to keep system simple.

B Build a complex event-driven system from the start.

C Implement notifications with a simple polling mechanism initially.

D Delay notifications feature indefinitely.

💡 Hint

Consider starting simple and improving later.

Option C balances requirement fulfillment and complexity by starting with polling, which is simpler than event-driven systems.

❓ component

expert

Identifying Components from Use Cases

Given use cases: User Registration, Payment Processing, Order Tracking, which component should handle the 'Payment Processing' use case in a modular system?

A User Interface Component

B Payment Gateway Component

C Authentication Component

D Order Management Component

💡 Hint

Think about which component deals with money transactions.

Payment Processing is best handled by a dedicated Payment Gateway Component to isolate payment logic and security.