Nice explanation Daniel, Tacit with hooks!
Xmas1t=: +/@#~ (= 1&|.) Xmas2t=: +/@#~ (= -:@$ |. ]) Cheers, bob > On Nov 30, 2017, at 10:43 PM, 'Pascal Jasmin' via Programming > <[email protected]> wrote: > > tacit just enough to avoid repetition > > +/ (#~ ] = 1 |. ] ) a > +/ (#~ ] = -:@# |. ] ) a > > > > > ________________________________ > From: Daniel Lyons <[email protected]> > To: [email protected] > Sent: Friday, December 1, 2017 12:49 AM > Subject: [Jprogramming] Advent of Code, Day 1 (spoilers) > > > > The problem statement has to do with summing up digits in a large number if > the digit matches the following digit, with wraparound. > > > My concept is to take the input as an array of single-digit numbers, compare > this to itself rotated forward a digit. Wherever those match up, the > following digit is a match. I can then copy to select the values that match > and then simply sum them up. It works out like this: > > > NB. First I want digits, so: > > a =. "."0 '<my big captcha string>' > > > NB. Part 1: the idea is to line up the input against itself, rotated right > one > > +/ a #~ a = 1 |. a > > > This worked, and then the twist in problem 2 turned out to be easy to > compensate for: instead of hard-coding 1, calculate half the length of the > array: > > > NB. Part 2: rotate by half the length > > +/ a #~ a = (-: $ a) |. a > > > I did not even try to define these as functions, since I was sure I'd lose > the plot trying to make them tacit and get frustrated. > > > -- > > Daniel Lyons > > > > > > ---------------------------------------------------------------------- > > 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
