Keep Room for the Ship
Hard
Used by Smart Hint
A ship here would block every remaining spot for one of the ships still to place, leaving it nowhere to go — so this cell is water.
- Ship segment
- Water
- Cells that establish the pattern
- Where the conclusion lands
How it works
- The same row as Placement Overlap: the 3-ship fits only as the left three cells or the right three, so the middle two are already known to be ship.
- Now look at the two cells directly below them. A ship in either one would touch the 3-ship whichever of its two spots it really takes — and it has nowhere else in the grid to go.
- So both cells are water. (The cells below the row's two ends are already water for the simpler reason that ships never touch at a corner.)