One nice thing about 5 p: over totient is that it returns integer instead of float.
3!:0 totient 10 8 (3!:0) 5 p: 10 4 On Wed, Mar 15, 2017 at 10:25 AM, 'Mike Day' via Programming < [email protected]> wrote: > Had a new look at the problem. Reworked verbs as I'd not kept the > old. First pass, pretty brutal, took ~100 sec, in j806beta with avx. > Later efforts to speed it up were worse! Evidently better to compare > sorted character reps of numbers than sorted base 10 decodes. > > M > > Please reply to [email protected]. > Sent from my iPad > > > On 15 Mar 2017, at 07:48, 'Mike Day' via Programming < > [email protected]> wrote: > > > > Only just up - having breakfast! I evidently solved it, as the > project's discussion thread > > is open to me, but I don't have a record of my method. > > > > Early-ish PE problems were amenable to brute force, and I expect that's > how I would have > > done it. > > > > AFAIrecall, later problems involving phi require insight how phi is > calculated: > > > > if n = */p^q, phi(n) = */(p^(q-1)) * p-1 > > eg > > q:360 > > 2 2 2 3 3 5 > > p =: 2 3 5 > > q =: 3 2 1 > > > > */(p^q-1) * p-1 > > 96 > > > > 5 p: 360 > > 96 > > > > so n/phi(n) is > > */@:(%<:) p > > 3.75 > > > > No time for more - away from wifi for 10 hours or so! > > Mike > > > > > > > >> On 15/03/2017 03:09, Don Guinn wrote: > >> My second approach was brute force like you did. It gave the same > number as > >> my first approach. And interestingly it was faster than my first > approach. > >> Happens sometimes. The only thing I can think of is that I found the > answer > >> but I didn't supply what they wanted. I supplied the first number that > had > >> as a permutation of the digits given sorted by (%totient)n . I cheated. > >> Stole totient from J phrases. > >> > >> The only thing I can think of is that they wanted something other than > the > >> n that I found. > >> > >> On Tue, Mar 14, 2017 at 8:12 PM, 'Jon Hough' via Programming < > >> [email protected]> wrote: > >> > >>> I just tried it and got the right answer. But my approach is > essentially > >>> brute force: > >>> I basically stringified (":) the totient result, sorted it, and > compared > >>> to the sorted stringified original number. > >>> > >>> I can be more specific if you like. > >>> > >>> Regards, > >>> Jon > >>> -------------------------------------------- > >>> On Wed, 3/15/17, Don Guinn <[email protected]> wrote: > >>> > >>> Subject: [Jprogramming] Project Euler > >>> To: "Programming forum" <[email protected]> > >>> Date: Wednesday, March 15, 2017, 9:37 AM > >>> > >>> Has anyone out there solved problem > >>> 70? I have worked it two ways which > >>> give the same answer but it is given as incorrect. I don't > >>> want to divulge > >>> what I did as that is against their rules. I must be missing > >>> something and > >>> presenting the wrong number for the result. Or is it > >>> possible that their > >>> answer is wrong? > >>> > >>> Glad to discuss it in the forum, but if anyone wants to > >>> contact me > >>> privately so we don't break Project Euler rules, contact me > >>> at > >>> [email protected] > >>> > >>> Thanks. > >>> ------------------------------------------------------------ > ---------- > >>> 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 > > > > > > > > --- > > 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 > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
