Eugene is way ahead of us here -- and I think his observation was not so much specifically about this structural issue but instead a consequence of this issue.
Subtle distinction, perhaps... -- Raul On Fri, Jan 14, 2022 at 9:20 AM 'Michael Day' via Programming <programm...@jsoftware.com> wrote: > > Apologies to Eugene Nonko - I'd overlooked your remarks about the great > similarity between the > 14 segments. Plagiarism rules! > > Mike > > On 13/01/2022 23:34, Eugene Nonko wrote: > > I did solve it, but I didn't use J for that one. > > > > I wrote a translator in Perl that converted their assembly into C. C, > > because it's easier to read, plus I thought that some brute forcing might > > be required and compiled C will run faster than interpreting their assembly. > > > > While studying that generated C code I discovered that there are 14 very > > similar segments, each segment belonging to one of two types. Segments of > > one type increased the value of z and segments of another type decreased > > the value of z given some condition. That allowed me to reduce the size of > > search space from 9^14 (too large) to 9^7 (very manageable). > > > > -- Eugene > > > > On Thu, Jan 13, 2022 at 2:17 PM Raul Miller <rauldmil...@gmail.com> wrote: > > > >> https://adventofcode.com/2021/day/24 > >> > >> I have not completed the day 24 puzzle. > >> > >> The day 24 puzzle has a sequence of instructions representing a > >> calculation to verify a model number (and conceptually enable features > >> based on that model number -- though part A of the puzzle does not > >> provide any details about that). > >> > >> The processing unit performs integer calculations, and has four > >> registers: W, X, Y and Z. > >> > >> There are six instructions, one which inputs a digit of the model > >> number, an add instruction, a multiply instruction, an integer > >> division instruction, a modulo instruction and an equals instruction. > >> > >> The input instruction always inputs to register W (and is the only > >> instruction used to update W). The div instruction always divides by 1 > >> or 26. The modulo instruction is always used to find a remainder > >> modulo 26 (and always only operates on positive values, or 0 for the > >> numerator). The multiply instruction seems to always multiply by 0 or > >> powers of 26. (To load a value into a register, the register is first > >> multiplied by 0 and then has another value added to it.) > >> > >> A certain amount of simplifications are possible using math identities > >> and range constraints. But I do not have much more that's useful to > >> say until I've found a way of solving the puzzle. > >> > >> Here's a snapshot of where I'm at, trying to work through these issues > >> (looks sloppy with a proportionally spaced font): > >> > >> ... > >> digit13 NB. W234=: W216 inp 13 [ 1 thru 9 > >> 0 NB. X235=: X223 mul 0 [ 0 > >> add Z228 Y232 NB. X236=: X235 add Z233 [ 9 thru 5520918021 > >> mod 26|Z233 26 NB. X237=: X236 mod 26 [ 0 thru 25 > >> mul <.Z210%26 X223 NB. Z238=: Z233 div 26 [ 0 thru 212343000 > >> add X237 _4 NB. X239=: X237 add -4 [ _4 thru 21 > >> eql X239 digit13 NB. X240=: X239 eql W234 [ 0 thru 1 > >> eql X240 0 NB. X241=: X240 eql 0 [ 0 thru 1 > >> 0 NB. Y242=: Y232 mul 0 [ 0 > >> 25 NB. Y243=: Y242 add 25 [ 25 > >> mul 25 X241 NB. Y244=: Y243 mul X241 [ 0 thru 25 > >> add Y244 1 NB. Y245=: Y244 add 1 [ 1 thru 26 > >> mul <.Z228%26 Y245 NB. Z246=: Z238 mul Y245 [ 0 thru 5520918000 > >> 0 NB. Y247=: Y245 mul 0 [ 0 > >> digit13 NB. Y248=: Y247 add W234 [ 1 thru 9 > >> add digit13 7 NB. Y249=: Y248 add 7 [ 8 thru 16 > >> mul Y249 X241 NB. Y250=: Y249 mul X241 [ 0 thru 16 > >> add Z246 Y250 NB. Z251=: Z246 add Y250 [ 0 thru 5520918016 > >> > >> I am currently working on some tree unification mechanisms (maximum > >> common subtree elimination to let me better inspect the partially > >> resolved calculations). > >> > >> I believe Eugene Nonko has solved this one, though I do not know if he > >> found J useful in his approach. > >> > >> FYI, > >> > >> -- > >> 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 > > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
