Afraid not, but it appears that Linda's ff verb is correct, returning 1999998 as the area for the required rectangle. It's frowned on to publish the answer.
I wish I could find my own solution to this; I evidently did solve it, probably some years ago, as I can "see" the right answer displayed when I log in to Project Euler and look at problem 85. I can't find any solution in my files, be it J or APL or Fortran, let alone Python (which I don't really get yet) or Pari GP, which I use when I can't get sufficient precision from J (probably my own limitations rather than J's). Though, fwiw, I was having trouble last week with p482, about incircles and stuff, running slow and wrong in J, and recoded it in Pari GP. I got the same answer and about 5 times slower in Pari GP! I eventually spotted the lacuna and got a J solution running in about 1 1/2 hours. It appears to me that PE problems have increased in both mathematical difficulty and programming complexity over the years. If Problem 85 were to be problem 485, that 2 million might now be 2e9 or worse. Perhaps not, as I can't remember my algorithm! I did achieve solving all problems some ago, when there were fewer than 200, but I'm 90 odd behind now. Meanwhile, seeing if I can solve last weekend's problem 483 (prima facie about permutations and cycles). Today's (484) concerns a Möbius function with n=20 000 000; haven't thought about it at all yet, although 18 have already solved it. Mike On 12/10/2014 11:30, Linda Alvord wrote:
At the moment, I'm rooting for 54 by 54 as the answer! ff=: 13 :'(>:i.x) */>:i.y' f=: 13 :'*/~ >:i.y' (7 ff 7)-:f 7 good=: 13 :'}:1,x>+/\,y' sum=: 13 :'+/(x good y)#, y' 400 < 400 sum 5 ff 5 400 < 400 sum 6 ff 6 400 < 400 sum 7 ff 7 400 sum f 6 400 sum f 7 400 sum f 8 6 ff 6 400 sum 6 ff 6 2e6 < 2e6 sum 52 ff 52 2e6 < 2e6 sum 53 ff 53 2e6 < 2e6 sum 54 ff 54 2e6 sum f 53 2e6 sum f 54 2e6 sum f 55 2e6 sum 54 ff 54 This stays in 2 dimensions. Linda -----Original Message----- From: programming-boun...@forums.jsoftware.com [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Raul Miller Sent: Saturday, October 11, 2014 6:10 PM To: Programming forum Subject: Re: [Jprogramming] Project Euler 85, Python and J I understand that boxed index lists can be used to index multi-dimensioned arrays. And that can be a convenient abstraction. However, I have been dealing with very large datasets recently, and boxed data on the critical path, at least for some operations, becomes prohibitively slow. When I can use regular numeric structures to replace irregular boxed structures, the overall speedup from the representation change usually more than makes up for the cost of changing representation. Thanks,
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