Dr. Sudoku Prescribes #45 – Battleships
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: Just Try Two Find Us
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 Standard: Battleships Grandmaster = 1:45, Master = 2:45, Expert = 5:30
Solution: PDF
1. I did it in 1:39.
2. Before I go celebrating though, the funny part is that I know that I only did it that quickly because I accidentally had thought that R4C10 was X’d out prematurely (I got me some old eyes), and it made other decisions that should have taken longer almost automatic. I realized my mistake about 15 seconds too late, but figured “WTF” – might as well keep going and see if it was accidentally correct. I am the Chauncy Gardener of the puzzle world today.
Thanks.
TheSubro
10 : 26 s!
1:38 on this one. I think it deserved only around 50 seconds.
How do I unfavourite a puzzle? I pressed favourite on this by accident.
Right now I believe the only option is to go to thegriddle.net, go to your profile page, and unfavorite over there. I mentioned your concern to David and he will see if he can build it directly into the widget above.
This puzzle actually yields to two basic solving techniques covered by Tom in other posts: placing the battleship, and accounting for all submarines.
After inserting the obvious ship segments at C4, E6, and E8, we arrive at the following position [Legend: L/M/R/*/_/. = left, middle, right segments, generic-segment, water, empty] (I apologize in advance if the board doesn’t render correctly as monospaced — I’ll only know if it displays well after I submit this comment!):
1
1 2 3 4 5 6 7 8 9 0
+---------------------
A | . . . _ . . . . . . 3
B | . . _ _ _ _ . . . . 4
C | . . . * R _ . . . . 4
D | . . _ _ _ _ _ _ _ . 1
E | _ _ _ _ _ L M R _ _ 3
F | . . _ O _ _ _ _ _ . 2
G | _ _ _ _ _ _ _ _ _ _ 0
H | . . . _ . _ . . . . 2
I | _ _ _ _ _ _ _ _ _ _ 0
J | . . . _ . . . . . . 1
2 2 2 2 2 2 2 2 2 2
There are only two places to put the battleship: C2-C5 and B7-B10. Inserting it at C2-C5 forces a second battleship at B7-B10, so the battleship goes in B7-B10.
Inserting obvious ship segments at J6 and H9 brings us to the critical position:
1
1 2 3 4 5 6 7 8 9 0
+---------------------
A | . . . _ . _ _ _ _ _ 3
B | _ _ _ _ _ _ L M M R 4
C | . . . * R _ _ _ _ _ 4
D | . . _ _ _ _ _ _ _ . 1
E | _ _ _ _ _ L M R _ _ 3
F | . . _ O _ _ _ _ _ . 2
G | _ _ _ _ _ _ _ _ _ _ 0
H | . . . _ . _ _ _ * . 2
I | _ _ _ _ _ _ _ _ _ _ 0
J | _ _ _ _ _ O _ _ _ _ 1
2 2 2 2 2 2 2 2 2 2
The insight need here, covered by Tom elsewhere, is that all four subs are accounted for: F4, J6, row F, and column 5. Since there can be no other submarines, H10 must be a ship segment (otherwise H9 would be a fifth submarine). From here the rest is trivial.
If I could make a request of the excellent solvers who post to this blog, it would be to share their solving logic and techniques where possible. Back in 2005 I posted the following on Raymond Chen’s “The Old New Thing” in a thread relating to the Freecell solitaire game, but the comment is equally relevant to Solitaire Battleship puzzles:
Like solving a good chess problem, like cryptanalyzing a difficult cipher, IMHO the payback in solving these puzzles is honing your skills for the next puzzle. Just my $0.02.
Another very enjoyable puzzle — thanks, Tom!
7:17 aaargh. Battleships is the type that once you miss something, you keep missing it forever and ever