Finally got the answer. Same one I had put in earlier but was rejected. Windows 10 had a big update overnight and the system rebooted. Who knows what happened.
On Wed, Mar 15, 2017 at 1:48 AM, '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
