State diagrams in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding State Transitions in a State Diagram

Consider a state diagram for a simple traffic light system with states: Green, Yellow, and Red. Which of the following correctly describes the transition sequence when the light changes?

A Green → Yellow → Red → Green

B Green → Red → Yellow → Green

C Red → Green → Yellow → Red

D Yellow → Green → Red → Yellow

💡 Hint

Think about the normal traffic light cycle on roads.

The typical traffic light cycle goes from Green to Yellow, then Red, and back to Green.

❓ Architecture

intermediate

Identifying States in a User Authentication Flow

In a state diagram representing user authentication, which of the following states is NOT typically part of the flow?

A Password Reset

B Logging In

C Logged Out

D Data Processing

💡 Hint

Consider the states directly related to authentication.

Data Processing is not a state in authentication; it is a separate process.

❓ scaling

advanced

Scaling State Diagrams for Complex Systems

When designing a state diagram for a complex system with many states and transitions, which approach best helps manage complexity?

A Use only two states to simplify the diagram

B Avoid using states and rely only on event-driven logic

C Use hierarchical states to group related states

D List all states and transitions in a single flat diagram

💡 Hint

Think about how to organize many states logically.

Hierarchical states group related states and reduce clutter, making diagrams easier to understand.

❓ tradeoff

advanced

Tradeoffs in State Diagram Detail Level

What is a key tradeoff when choosing the level of detail in a state diagram for a software system?

A More detail improves clarity but can make the diagram overwhelming

B Less detail increases the number of transitions

C More detail reduces the number of states needed

D Less detail always makes the diagram more accurate

💡 Hint

Consider how too much information affects understanding.

Adding more detail can clarify behavior but may overwhelm readers with complexity.

❓ estimation

expert

Estimating Number of Transitions in a State Diagram

A system has 5 states. Each state can transition to any other state except itself. How many transitions are there in the state diagram?

A 25

B 20

C 10

D 5

💡 Hint

Calculate transitions as possible pairs excluding self-transitions.

Each of the 5 states can transition to 4 others, so 5 × 4 = 20 transitions.