Design a Crossword Puzzle Solver
Hard · System Design · about 45 minutes
Asked at OpenAI, Google, Microsoft.
Design a service that fills crossword grids: users submit a grid with blocked cells and any pre-filled letters, and the system returns a fill where every across and down slot is a dictionary word, or reports that none exists. Hard grids can take minutes of search, so the work must be spread across many workers, with cancellation and caching.