Solution to Problem 18

Solution to Problem 18: "Battleships #2"

	If B6 or D6 were a ship square, then C5 and C7 would both be water squares. This is not possible, because column C must have six ship squares in it. Therefore, B6 and D6 are both water squares. Columns B, C, E, G, H, and I total nineteen of the twenty ship squares. The twentieth square must be either A6 or F6, the other is a water square. If F6 were a ship square, then E6-I6 would be five ship squares in a row, which is not possible. Therefore, A6 is a ship square, all of the unknown squares on row 6 are ship squares, and all of the unknown squares on rows A, D, and F are water squares.
	The only places for the remaining cruiser and the battleship are C5-C9 and I1-I4. Therefore, we know that C7, I2, and I3 are definitely ship squares. If either C1 or C3 were a water square, then the only way to fill column C would be to have a five-space ship, which is not possible. Therefore, both C1 and C3 are ship squares.
	If G4 were a ship square, then it would be the fourth submarine, but there would be no way to complete row G without an additional submarine. Therefore, G4 is a water square, and the rest of column G are ship squares. The last of the submarines must be at B1-C1, so the cruiser is at I2-I4, the battleship at C5-C8, and the last submarine at I8.
	The submarines are at A6, C3, E6, and I8.

Comments: I didn't spend much time on either of the Battleships puzzles, but I honestly thought that this one was easier than the first. There was the one crucial piece of information in the second paragraph of the first frame, and after that you were sailing downwind.

I guess the reason I didn't solve this puzzle is that I didn't notice that it was a 9x9 grid instead of the more usual 10x10. I think I would have put in the time to solve this one if I had. I guess the moral for me is "Make haste slowly".