Roomba algorithms and visualization

I once had an interview question asking for an algorithm for a Roomba┬áthat ensures it covers every square of a room divided into grid cells, given that the room shape and location of obstacles are unknown. It’s similar to the idea of solving a maze, except that instead of getting to a specific point, you’re trying to visit every point in the room – to clean it!

It’s a pretty common problem, but I hadn’t seen it in the guise of a physical robot before. Running a Depth First Search covers every piece of floor easily enough, but casting it as a physical device that has to move implies a large cost to popping back up the stack that’s generated during DFS. There’s a lot of backtracking in a DFS based approach for a Roomba, so it makes for a slower vacuuming job.

It made me wonder whether there was some better approach than DFS that would be more efficient.

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