Nurikabe by Prasanna Seshadri
or solve online (using our beta test of Penpa-Edit tools)
Theme: Daniel Cohen (alphanumeric conversion of top/bottom rows; i.e., 4=D, 1=A, 14=N, …)
Author/Opus: This is the 117th puzzle from our contributing puzzlemaster Prasanna Seshadri.
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 Standards (highlight to view): Grandmaster = 6:15, Master = 11:30, Expert = 23:00
Solution: PDF
Note: Follow this link for other classic Nurikabe. If you are new to this puzzle type, here are our easiest Nurikabes to get started on.
Oh my, that was frustrating… after over an hour of pointless trial and error I accepted the fact that this is one of those nurikabe puzzles where all the islands just barely fit and forcing single cells and looking a few steps ahead wouldn’t help. Then I changed my approach, drew in where the ocean had to sit very roughly and just fiddled with the islands until it worked through pure chance. Even that took me a very long time, and I didn’t feel like I used much logic along the way. Did others find a more logical path?
The one thing I did realize (which is one of those things where, once I get it it seems obvious and I might have used it before without realizing) vf gung jvgu nyy gur pyhrf nebhaq gur rqtr, vg perngrf n Lva-Lnat yvxr fvghngvba jurer lbh pna arire unir gjb vfynaqf qvntbanyyl gbhpuvat, juvpu urycf urer naq gurer.
Nabgure guvat vf gb ernyvmr gung lbh arrq gb zvavzvmr gur ahzore bs fgernz pryyf nf zhpu nf cbffvoyr, naq gurer ner n srj zber onfvp qrqhpgvbaf gung pbzr jvgu gung. Na rknzcyr bs guvf vf, gur 2 ba gur rqtr univat vgf bgure pryy gb vgf evtug jbhyq zrna 7 fgernz pryyf gb pbire vg jurernf n iregvpny qbzvab jbhyq arrq whfg 6 fgernz pryyf.
Gurer ner n srj sbbgubyqf yvxr gung, ohg jvgubhg gur nffhzcgvba gung lbh arrq gb zvavzvmr gur ahzore bs fgernz pryyf, V qba’g guvax gurer’f zhpu va grezf bs ybtvpny cngu.
I solved it by pbafvqrevat jung pryyf gur hccre sbhegrra pbhyq cbffvoyl hfr, jung qverpgvbaf gur avar pbhyq tb (abg evtugjneqf gbb fbba), naq ubj zhpu fcnpr gurer jnf va gur gbc evtug sbe gur svir naq gjryir gb svg. Even with this, it still took me a good 30 minutes of trial and error.
I did notice the technique you point out, nygubhtu V gubhtug bs vg nf zber bs n pbeeny pbafgenvag, fvapr V fbyir gung chmmyr glcr zber bsgra. Gung urycrq cynpr n ahzore bs oynpx fdhnerf nebhaq gur rqtr, ohg nsgre gung V tbg fghpx sbe n juvyr. Gura, fvapr vg frrzrq yvxr gurer pbhyqa’g or nal rkgenarbhf oynpx fdhnerf, V qrpvqrq gb gel pnccvat bss gur sbhegrra vfynaq va gur ybjre evtug, juvpu sbeprq n srj zber pryyf va gung nern naq ghearq bhg gb or rabhtu gb srry zl jnl gb gur fbyhgvba.
For me, what helped narrow it down was cynpvat gur obggbz svir naq sbhegrra (gur ynggre pna’g cbffvoyl or havdhr vs vg qbrfa’g hfr gur jubyr obggbz evtug pbeare), juvpu tvirf na njxjneq juvgr pryy. Gura gelvat gb znxr guvatf jbex bhg nggnpuvat gung gb gur avar be gjryir znqr guvatf znantrnoyr.
Ah, this is my puzzle! Thanks so much Prasanna for constructing this one (love the theme) and thanks to Thomas and the rest of the contributors for this awesome site!