# On The Subject of Battleships

(This is part of a series of puzzles written for Timwi for a Secret Santa puzzle exchange, themed around various custom modules for the game Keep Talking and Nobody Explodes. No KTaNE knowledge is necessary for any of these puzzles except the final meta; each puzzle resolves to a single word or short phrase.)

# On The Subject of Battleships

• What is "Secret Santa puzzle exchange"? Commented Feb 12, 2020 at 0:56
• @AndrewSavinykh "Secret Santa" is a gift exchange usually done around Christmas, where everyone participating is randomly assigned someone else to buy a gift for. (The gifter is typically kept secret from the receiver for some amount of time afterwards.) I have a similar tradition with a group of friends, but instead of buying gifts we make puzzles for each other.
– Deusovi
Commented Feb 12, 2020 at 8:03
• This was a fantastic little logic puzzle. Thanks! Commented Feb 12, 2020 at 14:18
• @Deusovi thank you for explaining that, I am of course aware what "Secret Santa" is in general, I was just wondering was there a semi-official event on Puzzling, that I missed. Can you also explain why you have that many puzzles for the same person? Do you guys do it on a large scale? ;) Commented Feb 13, 2020 at 2:23
• @AndrewSavinykh Not on Puzzling, just with a group of friends I have off-site. And no, the only requirement is one puzzle - I just happened to have a lot of inspiration around that time.
– Deusovi
Commented Feb 13, 2020 at 7:41

Eleftheria i thanatos

Solved grid

Text extraction

The grid has the following text: "In order to peg relevant info, ignore most of this bad dreck, just examine odd ships middle glyphs for the text to finish now". After solving the grid, the middle glyphs of all ships of odd lengths reveal the message "Greek motto is" which solves to "Eleftheria i thanatos".

Solving path

Starting with the assumption that we have two battleship grids in one with grey numbers representing the sum of red and blue ships.

We take a look at the $$10$$ on the bottom. Because of the blue $$6$$ next to it, it can at most be a $$4$$ for blue. Because the sum of all red column clues is $$14$$, it can at most be a $$6$$ for red, allowing us to split the clue.

Having reached $$20$$ tiles from the red column clues, every column without a red clue does not contain any red ships. The two rightmost columns for red have to be filled by $$3 \times S2$$ horizonally and $$1 \times S3$$ vertically at the bottom.

Next we take a look at the second and third columns from the right for blue. To fill these in, we need $$4 \times S2+$$ horizontally and $$1 \times S2$$ vertically. The second row from the bottom tells us that the vertical $$S2$$ has to be at the bottom and that the $$S4$$ has to be placed in that row as well. This leaves only $$4 \times S1$$ to place, two of which have to be placed in the same row as the $$S4$$. This places only $$1$$ blue tile in the bottom row, leaving $$4$$ tiles for red to instantly fill in.

Since blue has only $$2 \times S1$$ left, the second row from the top can at most contain $$2$$ blue tiles and has to contain at least $$4$$ red tiles. With this information we can solve the red grid completely and split the remaining grey clues into the two colors.

To fill in the few remaining blue tiles, we have to notice that red and blue ships can not overlap. This gives us the solution to the second row and lets us fill in the rest of the grid.

• That's correct, nicely done! (And thanks for adding a summary of the logic! Pictures would be helpful, but the summary covers most of the intended deductions. This puzzle was a particularly difficult one, and I'm happy with how it turned out.)
– Deusovi
Commented Feb 11, 2020 at 16:16
• @Deusovi I'll add some pictures then. This was by far the best battleship grid I ever solved, several nice deductions.
– w l
Commented Feb 11, 2020 at 16:46
• Gargh, now I see why I struggled so much to solve this - I'd forgotten the assumption that ships of the same colour cannot border each other!! Any chance you could explicitly mention it early on in your answer please? I'm sure I won't be the only one who struggles to follow the logic here because they forgot (or never knew) that this is an unspoken rule... Thanks! :)
– Stiv
Commented Feb 12, 2020 at 10:06
• @Stiv I added a link to the battleship rules, is that enough?
– w l
Commented Feb 12, 2020 at 10:18