So, you're saying that converting a solved Sudoku into a real Sudoku puzzle is the hard part, i.e. may require more than 3 lines of J?
On Thu, Oct 14, 2021 at 12:20 PM Hauke Rehr <hauke.r...@uni-jena.de> wrote: > Depends on the norm :) > > You need to do just as difficult to perform steps: > trying to derive the next number; but you already > know where that next number is, so it requires > much less brute forcing (and backtracking). > It won’t take as many /steps/, as much /time/, > as solving. > > So I shouldn’t have stuck with the measurement > along the easy/hard axis but told you that I > was talking about the /number/ of steps. > > On the other hand, this is only true when we > compare the algorithms built using that routine: > can we rule out all but one digit at this place? > > There are different approaches where one or the > other (solving/generation) may actually be /easier/ > than the other. > > > Am 14.10.21 um 16:21 schrieb Devon McCormick: > > Easier said than done. > > > > On Thu, Oct 14, 2021 at 6:56 AM Hauke Rehr <hauke.r...@uni-jena.de> > wrote: > > > >> No, generation is easier. > >> Take a random permutation along both axes of > >> |."0 1~ >:i.9 > >> and then erase numbers as long as they’re derivable > >> by what remains. > >> > >> Am 14.10.21 um 04:19 schrieb Devon McCormick: > >>> I just put up this page from a past NYCJUG meeting where we talked > about > >>> sudoku - > https://code.jsoftware.com/wiki/NYCJUG/2012-11-13#Show-and-Tell > >> - > >>> and it only took me ten years! > >>> Perhaps a harder puzzle is to generate sudoku. > >>> > >>> On Wed, Oct 13, 2021 at 7:59 PM Hauke Rehr <hauke.r...@uni-jena.de> > >> wrote: > >>> > >>>> but since N2, N1 and N0 are boxed, > >>>> you need (N2;N1;<N0) rather than (N2;N1;N0) > >>>> or, even simpler since they’re already atomic > >>>> boxes (only one item, empty shape): > >>>> > >>>> > is&.>/ (N2,N1,N0) (<@mn@:{)"0 _ g > >>>> > >>>> you may even get rid of the "0 _ > >>>> (but read the vocabulary page for { carfully) > >>>> > >>>> > >>>> Am 14.10.21 um 01:37 schrieb Hauke Rehr: > >>>>> if I now understand your first question correctly, > >>>>> you want to learn how to shorten a phrase with > >>>>> much repetitive structure > >>>>> > >>>>> first of all, you can define 'is' this way > >>>>> is =: e. # [ > >>>>> > >>>>> > >>>>> your expression looks like > >>>>> (v N2{g) is (v N1{g) is (v N0{g) > >>>>> with v equal to mn etc. > >>>>> > >>>>> if you want to factor out g, you can say > >>>>> ((N2 v@:{ ]) is (N1 v@:{ ]) is (N0 v@:{ ])) g > >>>>> > >>>>> … and if you define > >>>>> MN =: mn@:{ > >>>>> you get > >>>>> ((N2 MN ]) is (N1 MN ]) is (N0 MN ])) g > >>>>> > >>>>> if what I wrote for a1, a2 and a3 is correct, > >>>>> you may then do > >>>>> > >>>>> > is&.>/ ((N2 MN ]);(N1 MN ]);(N0 MN ])) g > >>>>> > >>>>> which may be further simplified to > >>>>> > >>>>> > is&.>/ (N2;N1;N0) (MN&.>)"0 _ g > >>>>> > >>>>> and we may substitute back > >>>>> > >>>>> > is&.>/ (N2;N1;N0) (mn@:{&.>)"0 _ g > >>>>> > >>>>> I hope this works; and maybe someone wants to > >>>>> comment on different ways to reduce repetitive > >>>>> expressions. > >>>>> > >>>>> > >>>>> But if your main concern was solving the task > >>>>> of writing a sudoku solver, take a look at the > >>>>> wiki page Ric pointed to. > >>>>> > >>>>> > >>>>> Am 14.10.21 um 01:04 schrieb Hauke Rehr: > >>>>>> Concerning the first question: > >>>>>> > >>>>>> try adding ] where g used to be, > >>>>>> or inserting an & before the { > >>>>>> (but I didn’t study your code > >>>>>> enough to /know/ this will work) > >>>>>> > >>>>>> Am 14.10.21 um 00:52 schrieb 'Viktor Grigorov' via Programming: > >>>>>>> Hello, > >>>>>>> > >>>>>>> Recently I saw an article in lobste.rs > >>>>>>> (https://www.hillelwayne.com/post/sudoku/) about sudoku solving, > and > >>>>>>> though t, "it'd be nice to try it J". (Didn't even bother reading > it, > >>>>>>> but later glancing at it found the author had used J in the end. > :D) > >>>>>>> > >>>>>>> I reshape a list of integers of length 81 with blanks being 0s, > >>>>>>> row-wise, from top, going left-to-right; into a 4-cube of length 3; > >>>>>>> and define 3 auxiliary verbs. > >>>>>>> > >>>>>>> g=:3 3 3 3 $ ... > >>>>>>> q=:i.3NB. has missing > >>>>>>> hm=:0&=@(<./)@, > >>>>>>> NB. intersection > >>>>>>> is=:([e.])#[ > >>>>>>> NB. missing numbers > >>>>>>> mn=:13 :'((-.((>:@i.9)e.,y))#(>:@i.9))' > >>>>>>> > >>>>>>> Although one usually solves sudoku (I think) by thinking of > >>>>>>> exclusions, as the article's first paragraph or so suggested. I > >>>>>>> wanted to find symmetries or something similar, thinking of it as a > >>>>>>> higher dimmensional thing, hence the 4-cube. The constraints, or > >>>>>>> symmtetries, or whatever they may be are the 9 rows, columns, and > >>>>>>> faces each containing 1--9 once. My idea is to try each of the 81 > >>>>>>> cells until once with only one overlap is found, break, then repeat > >>>>>>> until no change. > >>>>>>> > >>>>>>> The sudoku given as an example in the english wikipedia article for > >>>>>>> sudoku has an 'easy' example, wherein the center of the center > >>>>>>> resolves to 5 using the intersection of the missing numbers of the > 5. > >>>>>>> row, 5. column, and 5. face; or within the tesseract: > >>>>>>> > >>>>>>> (mn(<1;q;1;q){g)is(mn(<1;1;q;q){g)is(mn(<q;q;1;1){g) > >>>>>>> ((mn(<1;q;1;q)&{)is(...)is(...))g NB. nope > >>>>>>> > >>>>>>> Taking out g and binding the from doesn't work, giving me just > 1--9. > >>>>>>> Trying to take out the coordinates doesn't fair well for me > either. > >>>>>>> > >>>>>>> How can one shorten the former expression using bindings? > >>>>>>> > >>>>>>> My second question regards is/: if I define a1, a2, a3 as missing > >>>>>>> numbers in the row, column, face of some cell, why does is/ a1 a2 > a3 > >>>>>>> give a syntax error, when a1 is a2 is a3 doesn't? > >>>>>>> > >>>>>>> > >>>>>>> > >> ---------------------------------------------------------------------- > >>>>>>> For information about J forums see > >> http://www.jsoftware.com/forums.htm > >>>>>>> > >>>>>> > >>>>> > >>>> > >>>> -- > >>>> ---------------------- > >>>> mail written using NEO > >>>> neo-layout.org > >>>> > >>>> ---------------------------------------------------------------------- > >>>> For information about J forums see > http://www.jsoftware.com/forums.htm > >>>> > >>> > >>> > >> > >> -- > >> ---------------------- > >> mail written using NEO > >> neo-layout.org > >> > >> ---------------------------------------------------------------------- > >> For information about J forums see http://www.jsoftware.com/forums.htm > >> > > > > > > -- > ---------------------- > mail written using NEO > neo-layout.org > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
