Dr. Sudoku Prescribes #46 – Battleship Sudoku

Battleship Sudoku by Thomas Snyder


or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between number placement, ship placement, and shading modes. The shading mode in gray, which numbers can be written on top of, may work better than default ship placement.)

Theme: Four Islands

Rules: Standard Battleship Sudoku rules.

Answer String: Enter the 8th row from left to right, followed by a comma, followed by the 6th column from top to bottom.

Time Standard: Battleship Sudoku Grandmaster = 5:30, Master = 8:00, Expert = 16:00

Solution: PDF

Note: Advice on solving this puzzle has now been posted in “Ask Dr. Sudoku #8

  • I had to do a bit of guess and check to get the 4-long ship placed (I had it down to two locations, and then made one more deduction to eliminate one of the locations). After that, the other ships were easily placed and then it was just fill.

    While I enjoy this variant quite a bit, once you get the ships placed, the fill is usually pretty easy.

    • Avatar photo drsudoku says:

      It’s a fair criticism. I design 90% of these so that the meat of the puzzle is in getting all the ships in and in the proper orientation. I rarely seek out to leave a hard (X-wing or even triple+) type sudoku solve. So the end should be just “dessert”.

  • Jack Bross says:

    I really enjoyed this puzzle. I agree with David that after the ships are in place, filling in the rest is pretty straightforward, but getting to the point where all the ships snap into place was interesting, and made use of some nice battleship logic.

  • skynet says:

    I am unable to proceed after placing all the one dimension ships.I think i can bifurcate and solve but i dont want to do that.Can someone show me the spolier?I have placed all 4 single ships

    • Avatar photo drsudoku says:

      Have you marked the rest of the columns with ship parts? There are 20 total, and they should all be accounted for. Then, figure out any arrangement that can satisfy the 242 in the center. There are no longer any submarines (1×1 ships) to help, so there aren’t many choices.

  • Carl W says:

    I was stumped for quite sometime to start this one, (much more so than the Saturday puzzle from the same week). When I finally stopped trying all the fruitless sudoku logic and took a really good look at Battleship geometries, things got much better. It was quite satisfying to derive the only possible layout for all those ships.

    I’m looking forward to reading Dr. Sudoku’s description for this puzzle to see how it compares to what I came up with.

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