About this puzzle

The Prompt Cache — practice the decision, scored against the optimum

What does the The Prompt Cache puzzle teach?

Put the stable, reusable context first — one early-changing segment busts the cached prefix for everything after it.

Why do interviews ask about this?

Prompt / KV caching is the LLM-cost interview — order requests to maximize prefix reuse and cut the tokens you’re billed for.

How is it scored?

The engine computes the provably-optimal answer for the exact instance you played (dynamic programming, shortest-path, or exhaustive search — never a heuristic) and scores your attempt as a percentage of it. No login needed to see your score.