The Strategy Pattern: Kill Your If-Else Ladders

Every LLD interview eventually reaches the same moment: a behavior that varies. Payment can be card, UPI, or wallet. Parking spots can be assigned nearest-first or cheapest-first. Feeds can be ranked by recency or relevance. Reach for if-else and you've told the interviewer everything they need to know. Reach for Strategy and the conversation changes.

The shape

Strategy has three parts: a context that needs a behavior, an interface that names the behavior, and concrete strategies that implement it. The context never knows which concrete strategy it holds. That's the entire trick.