Search found 92 matches

by pjt33
Tue Jan 30, 2024 2:49 pm
Forum: Number
Topic: Algorithm to determine a hidden attributes value
Replies: 5
Views: 514

Re: Algorithm to determine a hidden attributes value

Am I too stupid if I say that if you can check the sum for all the $\binom{100}{5}$ 5-objects subsets then you can build up a linear system of $\binom{100}{5}$ equations in $100$ variables? Not stupid, but you've fallen into a trap that's very easy to fall into. (I did too, and so did the person wh...
by pjt33
Fri Nov 03, 2023 11:43 am
Forum: Number Theory
Topic: How to enumerate/count the numbers of a particular form below N in an efficient way?
Replies: 11
Views: 6354

Re: How to enumerate/count the numbers of a particular form below N in an efficient way?

My technique gives theoretical asymptotics of $O(N^{23/24})$ for $\{1,1,1,1\}$, which doesn't really seem practical. Since then I have figured out how to do it in $\tilde{O}(N^{2/3})$ using standard techniques: sum the multiplicative function which evaluates to $N$ at primes and $0$ at higher power...
by pjt33
Thu Aug 24, 2023 12:44 pm
Forum: News, Suggestions, and FAQ
Topic: Suggestion - Expose API to public usage
Replies: 1
Views: 482

Re: Suggestion - Expose API to public usage

What API? A project which isn't designed with the goal of supporting application programmers doesn't necessarily have an interface for them to use. From what we can see, it's possible to infer that the site itself mainly accesses data dumps which are generated by a scheduled task rather than live da...
by pjt33
Mon Aug 14, 2023 11:54 am
Forum: News, Suggestions, and FAQ
Topic: Copyright and commercial use
Replies: 10
Views: 2431

Re: Copyright and commercial use

Doesn't the history of open source software teach us that companies will ruthlessly exploit people's passion projects for profit whenever it's possible to do it without having to pay the people who actually did the work a cent? How many of the proliferation of software licences come from the reactio...
by pjt33
Mon Aug 14, 2023 11:35 am
Forum: News, Suggestions, and FAQ
Topic: Problem notes
Replies: 4
Views: 4286

Re: Problem notes

I have a private "gist" on gist.github.com where I sketch partial results and ideas which need development. Obviously it's not an integrated UX, but it's an adequate means of accessing my thoughts on multiple devices without polluting my git repository of actual solutions.
by pjt33
Fri May 19, 2023 7:41 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 843
Replies: 14
Views: 764

Re: Problem 843: periods for n = 6 are {1, 2}

He does have a point. If it's a circle, it doesn't really have a beginning or end. If it has the same exact numbers in the same exact order, isn't it the same circle? No, it isn't. It may help to paint one of the buckets in a different colour to the rest to make an arbitrary fixed reference point.
by pjt33
Mon Apr 17, 2023 9:32 am
Forum: News, Suggestions, and FAQ
Topic: Statistics improvement
Replies: 4
Views: 303

Re: Statistics improvement

You can find that out by going to Statistics / Locations.
by pjt33
Fri Mar 10, 2023 12:15 pm
Forum: News, Suggestions, and FAQ
Topic: Security check gone?
Replies: 8
Views: 2363

Re: Security check gone?

There have been a few days when I've solved 5 problems, once within 6.5 hours. Starting fresh, I could probably knock off a lot of the first 50 very quickly. I don't think you need to worry about being banned for submitting a handful of answers an hour apart.
by pjt33
Sat Dec 24, 2022 8:59 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 808
Replies: 2
Views: 311

Re: Problem 808

Hebrew wrote: Fri Dec 23, 2022 4:47 pmSo which number is needed to be added/take in count into the sum once we have found that it is a reversible prime square? Only 169? Or 169 and 961?
Either of those could be correct, depending on their position in the list of ordered reversible prime squares.
by pjt33
Mon Nov 28, 2022 9:03 am
Forum: News, Suggestions, and FAQ
Topic: Errors/Warnings/Bugs
Replies: 766
Views: 258442

Re: Errors/Warnings/Bugs

It's probably not random: DB engines don't tend to randomise unless they're told it. I would guess that it's an artifact of the number of rows in the table. Wonder whether there's a PE question waiting to be written about unstable sorts and k-medians...
by pjt33
Thu Nov 24, 2022 8:31 am
Forum: News, Suggestions, and FAQ
Topic: "Collapsibility" behaviour for code fragments
Replies: 2
Views: 178

Re: "Collapsibility" behaviour for code fragments

I mean, we invest time and effort into solving the challenges and probably want to make sure, as our only reward, that everyone sees and appreciates our beautiful code and ingenious solution at first glance Given the amount of write-only code that I see in the discussion threads, that can't be the ...
by pjt33
Mon Nov 07, 2022 11:13 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 086
Replies: 81
Views: 32146

Re: Problem 086

hamsterofdeath wrote: Sun Nov 06, 2022 3:58 pm if yes, what is a candidate?
I think it's mainly there as a hint for people to sanity-check their approach. A candidate is a local minimum, up to symmetry of the cuboid. (You could argue that there are six candidates, but they come in symmetric pairs).
by pjt33
Wed Oct 05, 2022 8:37 am
Forum: News, Suggestions, and FAQ
Topic: "History" tab suggestion
Replies: 9
Views: 501

Re: "History" tab suggestion

The obvious solution to the MathJax problem is to not truncate the titles in the source HTML but instead place them in a div with a fixed width and CSS overflow:hidden . I don't guarantee it will work in practice, but in theory it seems correct.
by pjt33
Tue Sep 27, 2022 9:02 am
Forum: News, Suggestions, and FAQ
Topic: A tag that is always hidden on every problem
Replies: 2
Views: 199

Re: A tag that is always hidden on every problem

I am talking about a list of about 50 problems ( some of which I have solved , but most I haven't). Maybe you've already done this, but since you don't mention it: one next step would be to analyse the problems you have solved and see what the solutions have in common. Also, read their discussion t...
by pjt33
Wed Sep 14, 2022 8:13 am
Forum: News, Suggestions, and FAQ
Topic: Problem 60 wrong answer?
Replies: 3
Views: 442

Re: Problem 60 wrong answer?

br_klaus wrote: Sun Aug 14, 2022 6:40 pmThe answer should be X.
You really shouldn't post answers to problems like this. I've flagged it for the admins, but if you get there first then please edit out the answer.
by pjt33
Mon Aug 29, 2022 9:24 am
Forum: Number Theory
Topic: Tree of Eisenstein triples
Replies: 3
Views: 8837

Re: Tree of Eisenstein triples

We know that the primitive Pythagorean triples can be generated using (3,4,5) as a seed Or, indeed, using (0, 1, 1) as a seed, although the first layer of expansion is inelegant. (This seed is an eigenvector of one of the matrices, and the other two give the same expansion). (0, 1, 1) similarly ser...
by pjt33
Sat Jul 30, 2022 12:26 am
Forum: Resources
Topic: The chess puzzle that led to a Fields Medal
Replies: 6
Views: 1244

Re: The chess puzzle that led to a Fields Medal

jaap wrote: Fri Jul 29, 2022 12:41 pm Yes, but only orthogonal king moves, not diagonal ones.
True, it's really a wazir.
by pjt33
Fri Jul 29, 2022 8:56 am
Forum: Resources
Topic: The chess puzzle that led to a Fields Medal
Replies: 6
Views: 1244

Re: The chess puzzle that led to a Fields Medal

In particular, you can rearrange the squares to make a problem with an identical graph but where movement is king moves instead of knight moves: it's a row of 9 squares, a1 to i1, with the 10th square at d2. The white kings start at a1 and b1, and the black kings start at c1 and d2. This makes it mu...
by pjt33
Tue Jun 14, 2022 7:41 am
Forum: News, Suggestions, and FAQ
Topic: Extra credit
Replies: 2
Views: 395

Re: Extra credit

Have you seen the existing flair feature?
by pjt33
Mon Jun 06, 2022 11:18 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 025
Replies: 36
Views: 15311

Re: Problem 025

@Liquid25677, I don't see a way to answer that question which doesn't include a major spoiler for this problem, so I suggest that you solve the problem and then see whether the discussion thread which you unlock answers your question.