Dr. Sudoku Prescribes #9 – Nurikabe

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Nurikabe by Thomas Snyder


or solve online (using our beta test of Penpa-Edit tools)

Theme: Imbalance – the lower-left is slightly heavier than the upper-right, and is distributed less evenly, affecting the solve.

Rules: Standard Nurikabe rules.

Answer String: Enter the length in cells of each of the black segments (the unnumbered, connected “ocean”) from left to right for the marked rows, starting at the top. Separate each row’s entry from the next with a comma.

Time Standard: Nurikabe Master = 1:45, Expert = 5:15, Novice = 17:30

Solution: PDF

  • nehsb says:

    1:15 (0:46 for the first nurikabe)

    After the initial logic with the bottom-right small groups, solved it with purely intuition.

    I thought the end solution was rather pretty to look at. The 8 shape in the middle, with the two u-shapes next to it, and a pretty dense bottom right compared to the more open other 3 corners…

  • Ravi says:

    Nice puzzle – 10 min
    Only one crucial number, after that it just goes smooth.

  • Around 3 minutes. I loved the 8 in the bottom right area. The deductions to fill that in were non-standard, but still flowed nicely, and the themes from that section were reused in other parts of the puzzle. Very nice for an easy-medium Nurikabe.

  • TheSubro says:

    Took me about Expert level time, but I dont like the fact that the great times were based upon intuition as to the boring 2×4 8’s on the corners. Nothing compels such shapes from a quick overview, and it merely comes down to rather unimaginative shaping as compared to the attractive center 8, which itself was more symmetrical than necessary.

    For better or worse I am a turtle, who solves puzzles based upon logical moves at each step. While these intuitions may have been accurate in this relatively low level nurikabe, they would be unproductive if you had put more innovative shapings into the islands. In turn, poo-poo to them.


    • Avatar photo drsudoku says:

      The fast tester who set the lowest bar reported getting the interesting middle 8 quickly from observation. Then the corners. Some people are better at seeing that than others.

      That intuition is another route to fast times doesn’t mean I can rate a puzzle off scale for no reason. Many of these will be “Aha” based, so timing will be variable.

    • Farfarawayfan says:

      I’m agree with you.. If I can likes your comment here..

  • skynet says:

    28 mins 49 s…so i m not even included in the novice category!!

  • skynet says:

    Hi motris..is there any option to see the puzzles that i have attempted till date and on the dates that i have not attempted…for now i know it is only a few days but as the blog increases in size i would want to keep track of the days that i have not attempted..A very useful site this for getting slowly used to the different puzzles

  • skynet says:

    I would love to see this hard nurikabe puzzle in the ask dr.sudoku this weekend…..

  • muhorka says:

    This one took me 1:50, but I had after 30 seconds start again because of dumb mistake in the beggining. I think, that middle 8 wasn´t intuition, but it is only my feeling.

  • 1:48, The first one here that I’ve missed the expert rating. Ah well 😛 The I think I did all the hard spots quickly, just failed to spot the easy stuff around the 2 at the start.

  • DGPArtist says:

    Really struggling here. New to these puzzles! You are all talking about the centre 8, not sure how to go about it? Got most of the bottom corner from what I understand of the rules and solved the Harder puzzle #11. What am I missing?

    • Avatar photo drsudoku says:

      One problem in Nurikabe puzzles is the issue of finding enough space for islands, particularly when they can’t touch others. That middle 8 is pretty cramped, right?

  • Zotmeister says:

    The solution stream looks like a mountain with clouds passing in front of it 🙂 – ZM

  • Aaron Chan says:

    The middle 8 is very neat in how it is constrained.

  • Carl W says:

    As others have mentioned, the deduction for the middle 8 was quite lovely.

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