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3:54 AM

Writing an APL solution for this question, and I've got it working, but not very well golfed. Try it online, any tips for golfing (other than remove whitespace)?

Bubbler

4:41 AM

@JoKing First thing: simplify flattening at the end with ∊

Second: prefer ⍨s over ∘s with constant

ngn

@Bubbler ⌽¨∘(( -> ((⌽¨

Jo King

@Bubbler Is that second one just a general rule of thumb, because it isn't any shorter than the first. Actually, with one of the other golfs I figured out, it's one byte longer, though I might just be missing how to apply it in the second version

Bubbler

Oh. I thought it was shorter somehow

Jo King

Thanks for the ∊ though, I didn't realise that was what that did

ngn

@JoKing fails for "flybuys"

Jo King

4:51 AM

darn

I should test with multiple test cases hah

Bubbler

Fixing the bug happens to be shorter

I thought extracting the pattern could be shorter, but it really isn't...

@JoKing It's actually just trying out alternatives until you get a shorter one.

ngn

here's an idea: generate indices, encode them with 0 2 3, negate the digit correspond to 2, decode again, and sort according to the decoded

@JoKing 23 bytes - tell me if you want me to show them

Bubbler

5:09 AM

@ngn Is it excluding f←?

ngn

@Bubbler yes, without f←

the 23 bytes are an implementation of the encode-decode idea

Bubbler

@ngn I also got to 23 using the same idea but not explicitly using ⊥ or ⊤

Got 20 bytes.

ngn

@Bubbler wow. is it with a different method?

Bubbler

@ngn Very similar but doing arithmetic on indexes directly.

ngn

5:25 AM

@Bubbler got it!

i have 19

Bubbler

@ngn Me too.

And I got 17.

f←⍬∘(⍋⍋_______⍋)⊃¨⊂ (7 blanks)

Bubbler

5:53 AM

Spoiler

Jo King

How do you sort by indexes? I thought it would be ⌷, but 'abcd' ⌷ 1 2 4 3 throws a length error

Bubbler

@JoKing There are three main ways to do it: array[indexes], (⊂indexes)⌷array, indexes⊃¨⊂array.

Obviously you can't use the first one in trains.

Jo King

yeah, that makes me sad

Oh, err wait, what if the indexes are out of range? Like if it were 'abcd' ⌷ 5 6 4 3?

Bubbler

@JoKing Index error.

Jo King

no, I mean how would I sort by those numbers?

ngn

6:01 AM

@Bubbler interesting trick with ⍬⍋. if i had the same idea, i would have written it like this

Jo King

Oh, wait, I think I got it, I'd use ⍋ right?

Bubbler

@JoKing Right, it gives a permutation of 1..n (or 0..n-1), so it is perfect for rearranging tasks.

Jo King

Aha! f←(⊂(⍋⍳+⍴∘(3/6 0)))∘⍴⌷+ for 23 then

Bubbler

@JoKing That works, but ⊃¨⊂ is shorter.

Adám

@JoKing I wouldn't use + for identity. Use ⊢, lest you one day deal with complex numbers and get confused.

Bubbler

6:12 AM

@Adám IMHO, the actual problem is the function named "conjugate" not throwing DOMAIN ERROR on characters.

Jo King

@Adám i'll try to heed that warning

Adám

@Bubbler The cost of a half-century of backwards compatibility :-)

@Bubbler Although, now we're making it a "style". ⎕C will ignore numbers.

Jo King

I should probably use ≢ for length too

bleh, that renders badly

Adám

@JoKing Go Firefox! (or override with a font that has the glyph, e.g. one of these)

Bubbler

6:28 AM

I use CSS override plugin to force all code fragments to DejaVu Sans Mono (with the webfont from TIO).

ngn

@Bubbler 15 in k using the advantage of null reshapes

Bubbler

@ngn Even shorter in J.

ngn

it's got a builtin for split and reverse, lol :)

17 hours later…

TessellatingHeckler

11:18 PM

@ngn what do your explanations "neighbour graph" and "transitive closure" mean in this context? I think I can tell that neighbour graph is computing absolute distances between every 1 and every other 1, but in what way is it a "graph"? And the transitive closure - some logical operations turned into a matrix dot product, repeated until the match stops but what does that process do and why?

Bubbler

11:56 PM

@TessellatingHeckler Do you know what a graph is in this context?

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