In my opinion we should point out if a question is more atom-like then is appropriate for J. The most important in using J is thinking J-like, which I learned by studying Rich's J for C-programmers. So my wholistic solution is
(</. i.@#) 20 ?.@# 8 +-----+------------+-------------+----+-----+-----+ |0 3 6|1 2 5 7 8 17|4 10 13 18 19|9 12|11 15|14 16| +-----+------------+-------------+----+-----+-----+ in which everything about the nth duplicate can be found. E.g., if you want the value as well (~.;"0 (</. i.@#)) 20 ?.@# 8 +-+-------------+ |2|0 3 6 | +-+-------------+ |4|1 2 5 7 8 17 | +-+-------------+ |1|4 10 13 18 19| +-+-------------+ |3|9 12 | +-+-------------+ |0|11 15 | +-+-------------+ |5|14 16 | +-+-------------+ R.E. Boss -----Original Message----- From: Programming <[email protected]> On Behalf Of Raul Miller Sent: donderdag 27 januari 2022 19:11 To: Programming forum <[email protected]> Subject: Re: [Jprogramming] Find nth duplicate in vector Well, ... the implementation posted by xash is very nice, but in http://jsoftware.com/pipermail/programming/2022-January/059790.html Pawel Jakubas specified that the value appears first, and the index appears second, and that the indices start with 1 for the first value. Also, somewhere along the line, was the suggestion that the result of f should be empty rather than throwing an error if there was no such duplicate value. FYI, -- Raul On Thu, Jan 27, 2022 at 12:50 PM Hauke Rehr <[email protected]> wrote: > > I wonder why there’s still so much traffic on this thread > (okay, I’m to blame for quite some of it) > I thought xash published the best correct solution. > Am I wrong? > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
