This is an extension of Nilster's great puzzle: The Greenhouse Problem
The task is the same, but this time sprinklers cover only a 3x3 square around them. For completeness, here is the full set of rules:
- The greenhouse floor is made of tiles arranged in a 9x11 rectangle. The door is on the center of the 11-length edge.
- Each plant takes up 1 tile.
- Each plant needs to be watered by a sprinkler. Each sprinkler waters a 3x3 square around it.
- A plant and a sprinkler cannot be placed on the same tile.
- I must be able to reach every plant orthogonally. I cannot walk on plants or sprinklers. I can only move orthogonally.
- Asymmetry is allowed. The fewer sprinklers, the better, but there's no limit.
What is the most number plants possible in this greenhouse?