Object-oriented design rounds ask you to invent the types, not just fill in a function. The skill is scoping: enough structure to be correct, not an enterprise framework.
What Is It?
You are given a product-shaped prompt ("design an LRU cache", "model a parking lot"). You propose classes, methods, and complexity — then implement the hot path if asked.
When Do You Use It?
- Explicit "design a class / system API" prompts