### Dr. Sudoku Prescribes #70 – Battleships

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between ship placement and shading modes. In ship placement mode, right click gives sea, left click gives circle/square, left click and drag for rounded ships.)

Theme: Today’s date, which is featured twice in the clues

Rules: Standard Battleships rules.

Answer String: For each row from top to bottom, enter the number of the first column from the left where a ship segment appears. If the row is empty, enter 0. Enter these numbers as a single string with no separators.

Time Standards (highlight to view): Grandmaster = 2:00, Master = 3:00, Expert = 6:00

Solution: PDF

• chaotic_iak says:

02:12 darn. I solved it in 01:52; took 20 seconds to enter answer key.

I don’t know what made me to be able to solve Battleships really fast. Perhaps because I read the time targets first, but then again, the path is not terribly difficult: find largest ship, then svaq gur gjb pehvfref, gura hfr gur snpg gung n gjb ol gjb fdhner unf ng zbfg gjb fuvc frtzragf gb qrqhpr nyy pehvfref naq urapr onggyrfuvcf naq guerr fhoznevarf.

• drsudoku says:

When testing, I don’t consider the typing of the answer key as part of the time to solve the puzzle. I suppose if you are of an online competition mind-set all the time then that makes some sense.

• skynet says:

9:54 on this one

• chaotic_iak says:

Must be on the mindset of the Monday’s puzzle (where the “first answer key” is an instruction, and I thought the “second answer key” was also an instruction hence I didn’t stop the timer then) 😛

Oh right I didn’t comment on the puzzle did I? Well, seeing from the unusual approach, I’d say it’s very well made. Remembering certain tricks is always helpful, and here you seem to be forced to remember them before facing the puzzle for Grandmaster time. Or otherwise there is a simpler path that I missed, but as I hit Grandmaster, it seems pretty unlikely. (Grandmaster time is best time right?)

The theme itself is good, although the noises (33 and 1401) make it a bit hard to see the dates. And sadly you need the two seas (well, only one it seems; the other one is just to maintain symmetry I assume), otherwise you can make a good outside-clues-only Battleships.

Also, is it Battleships or Battleship? I seem to keep pluralizing (or unpluralizing) puzzle genres. But Wikipedia says Battleship while you say Battleships. which one is more common?

• chaotic_iak says:

Pfft so I don’t know why my phone can’t reply properly. The above reply (the one beginning with “Must be on the mindset”) is intended to reply your comment (the one beginning with “When testing, I don’t consider”).

• drsudoku says:

Wikipedia is not always right.

The style I try to consistently use is “Battleships” for the puzzle type and only singular for the adjective, like “Battleship Sudoku”. The USPC, Games Magazine (and therefore Conceptis Puzzles) all use Battleships. As did the classic Solitaire Battleships book by Gordon and Shenk in 1998. At least in the US, those are the relevant names to look at.

The board game is BATTLESHIP though, so some of the recent renaming of books to singular was due to tie-ins with that.

• drsudoku says:

Also, I certainly considered making the puzzle without the extra 6 clues, but needed more ship pieces and didn’t get as interesting a solve. Maybe I should just take to formatting some numbers in color when I want to highlight a theme.

• Aaron Chan says:

That is a strange break in, though it was a very nice puzzle.

V hfrq gur snpg gung n gjb ol gjb fdhner unf ng zbfg gjb fuvcf gb znxr qrqhpgvba ba ebj sbhe, juvpu sbeprf gur onggyrfuvc. Nsgre gung vg jnf cerggl rnfl nsgrejneqf. V fhccbfrq gung’f gur vagraqrq fbyivat cngu.

• drsudoku says:

Are we all going to rot13 everything now? I wanted to keep secrets on Monday but it seems likely some readers will be confused if we keep doing this.

That is an interesting break-in but I think there are some easier ones here.

Some of my intended work-ins focus on the fact that while there are 2 spots for the battleship, and 3 for the cruisers, those will fill up the 1 and 2 columns which can be marked off in other places. Marking off C5 and C7 is particularly helpful in forcing a cruiser in R1 and three subs in R2 which were the first sure ships I’d place.

• Aaron Chan says:

I just saw everyone doing it, so I followed suit. I am fine either way since I don’t usually read comments before solving.

• drsudoku says:

No worries. I should have called chaotik out on it up-thread first. Somehow it made sense to not spoil the Monday experience but I really don’t know that I want to see it happening all the time here.

• Para says:

Yeah, with Aaron’s opening, which I also used (and I like in Battleships), the one 4 spot gets removed. Then after placing the 4 ship, I did what you placed first.
But I had a feeling you intended for the two 4 options to be important in your design, but not what opened up the puzzle for me.

ps. I’m just sticking with ship size indications as the ship names are not exactly familiar to me in English.

• Tricia says:

I used this break-in. After that, noticing that I couldn’t place a two-unit ship (what are those, destroyers?) vertically in C1 was key.

I must be getting smarter; I wasn’t looking at a clock with a second hand, so I don’t know my exact time, but I definitely beat Grandmaster time today.