Hi Raul, your version is indeed a very nice simplification of my amend cludge. Also a nice job on the parsing of the input.
On Tue, Jan 4, 2022, 02:49 Raul Miller <[email protected]> wrote: > Because I could have expressed this clearer, here's a complete > implementation of day 13, based on Jan-Pieter Jacobs' approach: > > prep=: {{ > FOLD=.ALONG=.] > X=.|.Y=.0 1 > <@(".;._2);._2 toupper rplc&('=';'*';(LF,LF);LF,'/') y,'/' > }} > > fold=: [ ~.@:<. |@(-~ +:)&.|: > > a13=: [: # (fold {.)&>/ > > b13=: ' #'{~ ((i.@] e."1 #.~) 1+>./)F..(fold~)&>/ > > Using the noun 'sample' defined in > http://www.jsoftware.com/pipermail/programming/2022-January/059525.html > > a13 prep sample > 17 > b13 prep sample > ##### > # # > # # > # # > ##### > > > (Still looks better in a monospaced font, though...) > > Anyways, it's almost like this one was designed to illustrate J. > > -- > Raul > > On Mon, Jan 3, 2022 at 2:48 PM Raul Miller <[email protected]> wrote: > > > > Hmm... I thought I had had trouble using a bitvector left argument to > > u;.k (with k in _2 _1 1 2). I am glad to see that that actually works. > > I'll have to use that more in the future. > > > > (And, I noticed, while reading over my code, that I had left a line in > > my a13 which was nonsense because it used an earlier naming > > convention. Fortunately, it's an innocuous problem. But it's still not > > good.) > > > > C'est la vie... > > > > Anyways, I like the idea of doing the folds on the coordinate pairs > > directly. It was easy for me to visualize what was happening the other > > way, but your way is slick. > > > > That said, introducing a slight representation change (in pfold), you > > could have done this for fold: > > > > pfold=:(('xy'=11&{) * ".@(13&}.));._2@}.@:>@{: > > > > fold=: [ ~.@:<. |@(-~ +:)&.|: > > > > Which is ... nice (in my opinion). > > > > Thanks, > > > > > > -- > > Raul > > > > > > On Mon, Jan 3, 2022 at 2:06 PM Jan-Pieter Jacobs > > <[email protected]> wrote: > > > > > > Day 13 was sort of involved on the parsing part, and relatively easy > on the > > > actual solution. > > > I kept the dots in the coordinate domain, as it seemed less heavy > handed > > > than converting it to "paper", the transform is also very easy in the > > > coordinate domain. > > > I used the dots as is, and encoded the folds as axis, fold_position > pairs. > > > The append in singlefold updates the row (singlefold operates under > &.|: > > > such that x is the first row, and y is the second row) corresponding > to the > > > axis in the fold spec, where newrow calulates that row, performing the > > > actual fold. According to the spec, the fold line itself disappears, > done > > > by remfoldline. > > > > > > NB. process first part to array of dot coords > > > pdots=: (".;._2)@>@{. > > > NB. process folds, turning it in ints axis position pairs > > > pfold=:(('xy'i.11&{) , ".@(13&}.));._2@}.@:>@{: NB. folds > > > NB. Joint process verb for dots and folds > > > prep=: (pdots ; pfold)@(<;.2~ (2#LF)&E.)@,&LF NB. parse two fields > > > > > > i13=: prep in 13 NB. dots ; folds as (axis, index) pairs > > > > > > NB. A: how many dots after first fold; Dots treated as coordinate pars > > > NB. calculate folded row x: |:dots; y:|:fold spec > > > NB. index mirror dots@axis > > > newrow=: ({:@] ([-|@:-) ({~ {.)) > > > NB. Perform a single fold: x:dots; y:fold spec > > > NB. where,what,into: newdots, axis,dots under transpose, to make > > > dimension firstaxis in both dots and folds > > > singlefold=: (newrow`({.@])`[} &.|:) > > > NB. remove the fold line (left dots, right fold) > > > remfoldline=: ([ #~ ({"1~ {.@]) ~: {:@]) > > > NB. perform a fold (x: dots; y: fold spec), ~. because folding will > overlap > > > some dots, which should be counted only once. > > > fold=: singlefold ~.@remfoldline ] > > > > > > Part a performs the fold in the first fold spec, and counts the dots > > > surviving the ~. in fold. > > > a13=:[: # (fold {.)&>/ > > > > > > Part b does all folds and find 8 capitals; using F.. requires fold > specs to > > > be right hence it requires ~ . > > > > > > NB. draw draws the dots on a paper of a fitting size: x:dot coords; > > > seemingly, requires |: for not having vertical, mirrored text. > > > > > > draw=: [: |: ('#'"_)`]`(' '$~ >:@(>./)@])}~ > > > NB. do successive folds, then draw > > > b13=: (draw F.. (fold~))&>/ > > > (a13;b13)i13 > > > > > > Likely here and there, there could be some simplifications, e.g. > removing > > > the &.|: in singlefold and reversing arguments to be used with F.., > but the > > > above worked satisfactorilly. > > > > > > Just as a note, my solutions might be complicated, but I was not > solving > > > the problems in real-time ; actually, now I'm stuck on part B of day > 15, so > > > in two days, I won't be able to follow this tread (in real-time) > anymore > > > :/. No worries, I'll post my solutions when I get to solve the > problems. > > > > > > Jan-Pieter > > > > > > > > > On Mon, Jan 3, 2022, 03:43 Raul Miller <[email protected]> wrote: > > > > > > > https://adventofcode.com/2021/day/13 > > > > > > > > We are now past the half way point for these puzzles. > > > > > > > > For day 13, our puzzle was about getting the activation code (for a > > > > thermal camera). > > > > > > > > Example data looked like this: > > > > > > > > sample=:{{)n > > > > 6,10 > > > > 0,14 > > > > 9,10 > > > > 0,3 > > > > 10,4 > > > > 4,11 > > > > 6,0 > > > > 6,12 > > > > 4,1 > > > > 0,13 > > > > 10,12 > > > > 3,4 > > > > 3,0 > > > > 8,4 > > > > 1,10 > > > > 2,14 > > > > 8,10 > > > > 9,0 > > > > > > > > fold along y=7 > > > > fold along x=5 > > > > }} > > > > > > > > The numbers which look like coordinate pairs were coordinate pairs -- > > > > each marking a pixel on a sheet of paper. However, the coordinate > > > > pairs are "x,y" coordinates, so the first number in the pair selects > > > > the column and the second number selects the row. > > > > > > > > The "fold along" instructions were instructions on how to fold that > paper. > > > > > > > > So, the first step would be to convert the data to a list of fold > > > > instructions and a representation of that piece of paper: > > > > > > > > unpack=:{{ > > > > k=. 1+I.(LF,LF) E. y > > > > dims=.1+>./pairs=. _&".;._2 rplc&', ' k {. y > > > > folds=: 2 4 (;".)&>/@:{"1 ;:;._2 (k+1)}. y > > > > folds;|: (i.dims) e."1 dims#.pairs > > > > }} > > > > > > > > Here, the steps were: > > > > > > > > (1) Find the index of the blank line. > > > > (2) coordinate pairs precede that line, and the dimensions of the > > > > "piece of paper" would be 1 greater than the largest coordinate along > > > > each dimension > > > > (3) For the folds, we tokenize each line, extract the relevant tokens > > > > (and convert the numbers from literal to integer). > > > > (4) Finally, we package up the results. Transpose (|:) fixes the > > > > row/column vs x,y issue. > > > > > > > > S=: unpack sample > > > > > > > > For the first part all we had to do was figure out how to perform the > > > > first fold (and count the lit pixels). > > > > > > > > The rules for folding were that the axis we were folding on would be > > > > empty (no lit pixels), and when lit pixels overlap they merged to > > > > become a single pixel. In other words, we combine pixels using +. (or > > > > >.). > > > > > > > > The only real "trick" here is recognizing that the folded half is not > > > > only reversed but right (or bottom) aligned rather than the usual J > > > > alignment rule for argument cells. > > > > > > > > (Also, I implemented X folds using transpose and the Y fold > > > > implementation.) > > > > > > > > fold=:{{ > > > > 'label axis'=. y > > > > if. 'x'=label do.flip=. |: else. flip=. ] end. > > > > paper=. flip x > > > > assert. 0=+/axis { paper > > > > flip (axis{.paper) merge |.(1+axis)}.paper > > > > }} > > > > > > > > merge=:{{ > > > > shape=. x (>. * _1 ^ >&{.)&$ y > > > > x +.&(shape&{.) y > > > > }} > > > > > > > > With our fold operation defined, part a was trivial: > > > > > > > > a13=:{{ > > > > 'folds paper'=. y > > > > pairs=. |."1 pairs > > > > +/,paper fold {.folds > > > > }} > > > > a13 S > > > > 17 > > > > > > > > (Also be aware that 'fold' is a verb while 'folds' is a noun.) > > > > > > > > For part b, we were supposed to perform the entire sequence of folds, > > > > and then read the text represented by the resulting pixels. For the > > > > sample data, this was just a square (or a lowercase 'o'). > > > > > > > > Of course, for style points we ought to use a fold conjunction here > > > > (you can tell someone was having maybe just a bit too much fun > putting > > > > together these puzzles): > > > > > > > > b13=: {{ > > > > 'folds paper'=. y > > > > ' #' {~ paper ]F..(fold~) folds > > > > }} > > > > > > > > Sadly, my argument order was the opposite of what J's fold > conjunction > > > > needs, but that's simple enough to compensate for. (But ... this > could > > > > have been more concise.) > > > > > > > > b13 S > > > > ##### > > > > # # > > > > # # > > > > # # > > > > ##### > > > > > > > > > > > > (It looks better in a mono-spaced font.) > > > > > > > > -- > > > > Raul > > > > > ---------------------------------------------------------------------- > > > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
