How to Crack LLD Interviews (Low-Level Design) Like a Pro
You just got asked to design a parking lot system in your Low-Level Design interview. Your mind goes blank. You start drawing boxes. The interviewer looks unimpressed.
Sound familiar?
Here's the thing: LLD interviews don't fail people because they don't know UML or design patterns.
They fail because candidates:
- Freeze when asked to model from scratch
- Overthink abstractions
- Design too slowly
- Write rigid, untestable code
The fastest way to fix all of that?
Write code to build small games and tools.
They force you to think like a system designer — fast.
Why Games Are the Best LLD Training
Games are mini real-world systems:
- They have entities
- Rules
- State changes
- Edge cases
- Real-time interactions
And unlike textbook examples, they force you to:
- Model behavior, not just classes
- Think in flows, not boxes
- Refactor when your design breaks
That’s exactly what LLD interviews test.
And I don't mean design a beautiful looking game with a fancy UI. Just make a CLI version of any traditional game.
The Speed Advantage
In LLD rounds, you are judged on:
- How quickly you structure the problem
- How clearly you name objects
- How confidently you evolve the design
When you’ve built 10–20 small systems, you stop thinking about how to design — you just do it.
Speed comes from pattern memory, not theory.
Start With These Mini-Systems
These force you to think in terms of:
- State
- Turns
- Validation
- Separation of concerns
1. Tic Tac Toe
Teaches:
- State management
- Validation rules
- Win conditions
- Board abstraction
2. Snake and Ladder
Teaches:
- Object relationships
- Randomness
- Turn systems
- Rule engines
3. Parking Lot
Teaches:
- Resource allocation
- Strategy patterns
- Data modeling
4. Chess
Teaches:
- Inheritance vs composition
- Move validation
- Complex rule engines
Why This Works for LLD Interviews
In interviews you must:
- Clarify requirements
- Identify entities
- Define responsibilities
- Evolve design under feedback
Games train all four in one exercise.
You’ll naturally practice:
- SRP (single responsibility)
- Open/closed design
- Dependency injection
- State transitions
Without memorizing them.
Level Up With Standard LLD Problems
Once you’re comfortable with games, move to industry-style LLD systems:
- Rate Limiter
- Cache System (LRU, LFU)
- Notification System
- Logger Framework
- File Storage Service
These add:
- Concurrency
- Performance constraints
- Extensibility requirements
They push your design from toy systems to production thinking.
The Interview Preparation Strategy
- Warm up with a game or tool
- Identify entities & flows
- Write simple interfaces
- Implement basic behavior
- Refactor as constraints evolve
This mirrors real LLD interviews exactly.
Final Thought
Most people prepare LLD by drawing boxes.
Top candidates prepare LLD by building systems.
If you want to crack LLD interviews faster:
Build games. Build tools. Build often.
That’s how you learn to model systems — at speed.