The Nineteenth Byte

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00:00

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Q: AoC2021 Day 20: Wonky license check

Part of Advent of Code Golf 2021 event. See the linked meta post for details. Related to AoC2018 Day 8. The license file for an imaginary software system is defined as follows: The entire file is a sequence of non-negative integers. The entire file defines a tree of nodes. Each node in the tree...

caird coinheringaahing

A lot of the normal ones seem geared towards SO: "Complete eight consecutive reopen reviews, where the majority of voters agreed with you.", "Have five of your answers accepted by others in the same day.", "Write 10 positively-scored answers on open questions in one day."

Bubbler

Huh, the title is wrong again

frick

emanresu A

00:12

@NewPosts @Bubbler parsing?

Fmbalbuena

00:48

What are the differences between (?:..) and (...) in regex?

Riker

depends on the flavor, ?: is sometimes a non-capturing group iirc - i.e. it matches that group and saves it but ignores it in the eventual match

Fmbalbuena

Example using regex101.com?

Ginger Industries

@Riker personally I prefer the spicy flavor of regex

Riker

in that context, ? sets the 'flags' for the parentheses, and : sets 'doesn't capture'

Fmbalbuena

capturing? what is capturing in regex?

Riker

00:51

regex101.com/r/ArPn3r/1

@Fmbalbuena if you don't know what capturing is, i recommend reading a basic overview of how regular expressions work first

but as you can see in that regex, there are 3 sets of parentheses - but the first set has ?: and is therefore noncapturing

so it marks it as part of the match but not a 'group'

(i don't have a particularly good regex guide in mind so google is more helpful than asking me for one, I think)

Fmbalbuena

(?:b)a* and (b)a*?

Riker

those are both groups - hte first is a non-capturing one, second is a normal

hyper-neutrino

oh that is incredibly unfortunate. i was trying to make a test case for the lit-up room problem as an edge case that broke my first solution and ended up making ascii art of what looks way too close to being a swastika for me to suggest it for the problem ._.

Riker

that would match ba with any number (including zero) of a, but the groups of the regex wouldn't include the b

Ginger Industries

@hyper-neutrino that's a ಠ_ಠ from me

Riker

00:54

note: noncapturing groups are close to useless if you're not using other groups, i believe

like, there's no point - it doesn't affect whether or not the string matches or not directly

Unrelated String

if you aren't capturing some other groups you lose nothing by using capturing groups where you don't use what they capture

emanresu A

Nov 5 at 9:58, by emanresu A

When your code looks like a swastika

Ginger Industries

@emanresuA :|

lyxal

@hyper-neutrino that reminds me of a puzzle app which includes a puzzle kind which is literally the same as the challenge - if you set the grid to the min size and set square cover to 95%, you'd see that shape sometimes

Simon Tatham's puzzle pack for Android

It's been patched though

hyper-neutrino

@emanresuA what's your opinion on my io format (empty=0 light=15 wall=16)

Niko

01:00

trying to lit up the room with vyxal

Bubbler

@Riker Noncapturing groups are very useful when it is modified with * or + where capturing isn't quite what you want, and capturing impacts performance

Riker

@Bubbler when you're not using normal groups does the former matter? second makes sense good pt

Bubbler

e.g. (ab*)+ vs. (?:ab*)+

Riker

*matter, not pattern

Fmbalbuena

in regex, 10*1$ checks if the number is odd or even (binary)

Bubbler

01:03

Also noncapturing groups don't consume a slot of captured group, which is limited (often 100) in most regex engines, though you're probably doing something wrong if that actually matters

emanresu A

01:17

@hyper-neutrino If you mean by whether that's valid,

> You may take input as a matrix of characters or integers, [...]

hyper-neutrino

ok, cool

Jo King

01:37

@Fmbalbuena you only need the 1$ part (otherwise it won't match 1)

@cairdcoinheringaahing "Use Dark mode"

emanresu A

@cairdcoinheringaahing I've done #3 once or twice...

caird coinheringaahing

The only way to do it here is to post to old challenges and hope you get an upvote on enough of them

emanresu A

alephalpha is speeeeeeed

caird coinheringaahing

@cairdcoinheringaahing We've had 10 challenges in a day a few times recently, but that's including challenges that get closed

The last time we consistently had 10+ challenges per day was 2017

In fact, the last time we had 70 or more challenges in a week was the first week of August 2017 :/

Bubbler

10 challenges a day is actually too much, one can't consistently try all of them unless they have absolutely no life

hyper-neutrino

01:50

i think we have a good amount of people like that here

caird coinheringaahing

Especially now that its the winter (or summer) break for anyone in school/uni :P

hyper-neutrino

according to universitiesaustralia.edu.au/our-universities/…, it's on average not summer break for australian unis rn

lyxal

wdym? it is summer break rn

emanresu A

^ (except I'm not in uni)

hyper-neutrino

huh. ¯\_(ツ)_/¯ idk i thought your breaks didn't exactly line up with the inverse of ours but i guess i'm misremembering

lyxal

01:55

i've been on break since mid november lol

hyper-neutrino

oh wait, these must be the breaks that occur between term ends and starts, and ofc holidays are extra breaks anyway

lyxal

correct

hyper-neutrino

am smrt

emanresu A

Idk about Lyxal but we get mid-dec to start of feb off

hyper-neutrino

cuz it just so happens that my term is ending now so the winter break isn't so much a special winter holiday as just "the term's over and won't be starting til after the break" (for me at least)

lyxal

01:56

@emanresuA that used to be me

caird coinheringaahing

Yeah, Christmas :P

emanresu A

Aren't australian school holidays a week off NZ's?

lyxal

idk I'm not in school anymore

Unrelated String

@hyper-neutrino could you send me that test case before i post my sol

Jo King

this is just an extension of the "CGCC is busier during the week than the weekend" behaviour

hyper-neutrino

02:06

@UnrelatedString i didn't actually finish it i was halfway through and realized it was kinda sus

Unrelated String

ic

i'll just post then

hyper-neutrino

and also it doesn't even necessarily countercase my old solution

Unrelated String

lol

hyper-neutrino

i just realized my solution was brok and fixed it and in theory it should work

emanresu A

@UnrelatedString Wow thta's nice

Unrelated String

02:08

basically ripped off my solution to an older challenge lol

hyper-neutrino

oh wtf

Unrelated String

this lol

4

A: In Flanders Fields

Jelly, 18 14 bytes UÄUaÄa2 ZÇZoÇ_ Try it online! -4 bytes because I figured out what I did wrong with my cumulative sums Input and output is as two-dimensional lists with . mapped to 0, + mapped to 1, and * mapped to 2. (The footer on TIO converts automatically for convenience.) ...

user

@Bubbler Many of us here meet that requirement :p

pxeger

@hyper-neutrino it's summer at winter and vice versa for them, so they have a much longer holiday around december

hyper-neutrino

ik the summer winter flip i just misremembered the details of the break cuz like

i know their terms don't line up with us (i think they're near opposite because of the flip)

but i am stupid and forgot you can have breaks without it being between terms

pxeger

02:21

CMM: can I upvote this with an alt account, since it's not my challenge?

Bubbler

I upvoted it, so I'd say no

pxeger

ok

hyper-neutrino

i wonder how often Z(monad)Z is used in jelly

emanresu A

Hm, got trialogue

Unrelated String

...good question actually

hyper-neutrino

02:25

also i had a suspicion your sol wasn't correct and i am disappointed to say i was right

Unrelated String

f

pxeger

@hyper-neutrino 7 times in the corpus I have

Bubbler

I guess not much because you already have various pairs of built-ins that operate on rows and columns, and you can often get away with each

Unrelated String

it's a damn good thing we've got some pairs of things where one does one thing over rows and the other does the same thing over columns but i'm not sure how much it comes up outside those
also fwiw i am thinking of a 1 byte under-transpose in perhaps

hyper-neutrino

yeah i asked cuz i was wondering if a quick to do it would be useful :P

Bubbler

02:26

under transpose saves a byte only when the monad being transposed is an atom

hyper-neutrino

well technically it could save more if the monad being transposed is three links

because there is no 5x link combiner to do ZABCZ [?]

Unrelated String

specifically if it's being grouped already that is, i assume

hyper-neutrino

and instead of doing like ZABC[3]Z[3] you could do ABC[3][?]

Unrelated String

also in the case of a dyad but that seems
rare

Bubbler

Hmm probably yeah

Unrelated String

02:28

or specifically a dyad in a monadic chain

hyper-neutrino

oh true if you want to do this dyadically to like flip both the left and right side the current method is something like ZdZZ i think?

Unrelated String

@hyper-neutrino ...how the hell did i not think of that counterexample

pxeger

@pxeger (those are ÄUIÇÇÇÇ)

hyper-neutrino

@UnrelatedString it took me a while too and i even roughly knew what i was looking for

Unrelated String

frankly i'm surprised none of the existing test cases caught that now that i realize the problem

wait no

the sixth one does catch it

i'm fucking blind lmao

hyper-neutrino

02:32

LOL

how did i not notice

if you steal »×¥@\Ṛ$⁺ from the light-up section of my program you get a solution that's only 2 bytes longer than your current

and if I steal your second line instead of using my weird zip method I get a solution that's 2 bytes shorter than my current

pxeger

actually, there are a few more: _Ṃ$€ Ç€ Ṣ€

Unrelated String

mmm

hyper-neutrino

and then we'd end up with the same sol kekw

Unrelated String

i think i have some other idea half formed

hyper-neutrino

also ’Ạ instead of i1 is the same byte count and gets you nicer-looking output

Unrelated String

02:34

true

or even just... 1e

caird coinheringaahing

@hyper-neutrino Often enough for me to add a quick for it in my fork

Unrelated String

i

'm going to edit that in without a fix actually

hyper-neutrino

@cairdcoinheringaahing oh lol

@UnrelatedString ... frick

i was like "damn e@1 would look nice but i1 is shorter so screw output consistency"

💀

Unrelated String

we are so good at jelly

caird coinheringaahing

(Kind of, it's closer to <link>Z$2¡, but very similar)

emanresu A

02:35

You're better than I am

hyper-neutrino

@cairdcoinheringaahing oh i see

caird coinheringaahing

The trick is to pretend you know what you're doing enough that people assume you do :P

These atoms here are very... atomy :P

hyper-neutrino

also today i had the fun experience of rediscovering that ⁺ does NOT group the duplicated link so if you want to quick a doubled link you have to $ it again yourself

or just use 2 + upside down exclamation mark

caird coinheringaahing

@hyper-neutrino Oh my god, I hate that so much

Unrelated String

it can be useful

hyper-neutrino

02:37

it's arguably more useful than the other way around

because if it did group, you would not be able to split it up

caird coinheringaahing

I legit changed it in my fork to group, and that's one of like 3 non-backwards compatible changes I made

Unrelated String

i think i've used ⁺€ once or twice

hyper-neutrino

but since it doesn't, you can a) group it back together yourself pretty easily, 2) just use nrepeat x2

caird coinheringaahing

I think I added Ð small plus to behave as the old small plus did

Unrelated String

nice

hyper-neutrino

02:40

that would make sense

Unrelated String

...it just occurred to me, does base jelly really not have any 0-arity digraph quicks

i guess that's not too weird since it doesn't have a lot of digraph quicks to begin with

emanresu A

Something from Jelly that I'd really like in Vyxal: dyadic filter.

Redwolf Programs

Is that like JS's .filter?

hyper-neutrino

what exactly does that do

Razetime

i suppose filter the second arg after applying a function to the first and second

emanresu A

02:44

In jelly you can do stuff like L=¥Ƈ

(Filter by length is equal to other argument)

In Vyxal you have to use the register or similar annoying wizardry.

hyper-neutrino

oh wait i read that backwards

caird coinheringaahing

@UnrelatedString What would they do?

Unrelated String

that is a good question

caird coinheringaahing

The only zero arity quicks are the ones that call other links

pxeger

zero arity as in "not taking any other links", not "resulting in a nilad", right?

Unrelated String

02:47

having a version of ⁺ that duplicates the second-most-recent link could be useful but as a digraph it would be pretty marginal since if you're spending two bytes it's only a gain if you have to use a helper link for something else

yeah

emanresu A

chat.stackexchange.com/rooms/132318/unrelated-strings-stomach

Redwolf Programs

wtf

lyxal

shhh

we don't mention that here

@emanresuA so does that mean it'd be triadic?

emanresu A

what no

Bubbler

I propose a whole set of jelly-link-as-stack manipulation quicks

emanresu A

02:52

Oh wait yes actually

lyxal

> other argument

that means there's a function, an item to filter, and one other item to compare against

emanresu A

Yeag

Note: Function gets dyadified

pxeger

@Bubbler if we add enough, we could make Jelly parsing Turing-complete!

New Posts

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Q: Nesting list `n` amount of times

Given the input of n and value. The code is supposed to nest the single element list with value n times. This is code-golf, so the shortest code in bytes wins. Test cases: n = 1, value = 'a': ['a'] n = 2, value = 'a': ['a', ['a']] n = 3, value = 'a': ['a', ['a', ['a']]] n = 4, value = 'a': ['a', ...

code-golf sequence recursion

Unrelated String

@hyper-neutrino okay yeah i give up i'm stealing this lol

hyper-neutrino

03:09

lol

caird coinheringaahing

@NewPosts I think it might be because it's 3am, but I cannot get a solution working to this :/

hyper-neutrino

i have one but it involves using absolute references with superscripts and an eval STDIN so like

basically not even jelly at this point

Unrelated String

lmao

hyper-neutrino

because it keeps giving me [[[[[[1, 1], 1], [1, 1]], [[1, 1], 1]], [[[1, 1], 1], [1, 1]]], [[[[1, 1], 1], [1, 1]], [[1, 1], 1]]] for 1 x6 no matter how i reorganize it

well this question is going on HNQ 100%

Unrelated String

i think i have something

hyper-neutrino

03:15

oh wait my sol isn't even valid cuz it doesn't wrap the n=1 case

Unrelated String

are you sure it doesn't just look like it doesn't

i haven't actually looked myself

wait i completely misread the challenge i don't have something

pxeger

When OP answers their own question, incorrectly...

This doesn't work for n=1 — pxeger 27 secs ago

Unrelated String

okay i have a 5 byter

reminds me of the guy who self answered with a c# snippet that was missing necessary imports

emanresu A

CMQ: Is HTML "coding"?

Redwolf Programs

I say yes

TIL we have a new-years tag

hyper-neutrino

03:21

yes, even if HTML isn't a programming language you are writing something that is code i.e. "A system of symbols and rules that serve as instructions for a computer." (thefreedictionary.com/code)

caird coinheringaahing

@NewPosts FWIW, this was posted by a hat hunter :P

hyper-neutrino

this challenge's inconsistency annoys me

pxeger

I find it perfectly consistent

caird coinheringaahing

Jelly's problem with strings vs characters might be the issue @hyper-neutrino

hyper-neutrino

actually wait it's not inconsistent

just that just about every golfing language dies because you can't repeat pair

Unrelated String

03:23

use a number so you don't get any string vs character fuckiness

hyper-neutrino

whereas languages that can't do that efficiently and just ternary anyway are perfectly fine

caird coinheringaahing

-1 byte by remembering how ¡ works ;P — caird coinheringaahing 3 mins ago

Bubbler

someone should answer with Haskell's replicate and claim that Haskell list is essentially nested pairs :P

hyper-neutrino

i could've sworn i tried that at some point

caird coinheringaahing

@UnrelatedString :P

hyper-neutrino

03:24

ẋ,@/ works too anyway and i like it better

Unrelated String

oooh

i thought i tried that

nice

caird coinheringaahing

Damn, I tried that with x and it didn't work

emanresu A

@hyper-neutrino I literally just thought of that approach :P

caird coinheringaahing

Wait, why didn't it work

Unrelated String

i definitely tried something with both

hyper-neutrino

03:25

x doesn't work on numbers for some reason that i don't really understand

caird coinheringaahing

I'm too tired for golfing

Unrelated String

whatever i did worked fine for everything except n=

hyper-neutrino

wait, yes it does

Unrelated String

1

emanresu A

Dammit

Razetime

03:28

@NewPosts @DLosc i have 16 for this one, but i think there's a better way

Unrelated String

@hyper-neutrino wait no yeah this still doesn't wrap the deepest one

hyper-neutrino

well i came up with tio.run/##KyjKL8nP@59m@7/…

which is... literally just redwolf's js program but with extra brackets because proton sucks

for whatever reason a => b = c => d will try to assign c => d to a => b

Unrelated String

lol

Razetime

@Razetime ok, now at 12

hyper-neutrino

i also cannot explain tio.run/##KyjKL8nP@59m@z/P1q7M1q460Ta6LLY8IzMnVUNXN08TxNVJjE2s/… whatsoever

tio.run/##KyjKL8nP@59m@z/…

i hate this abomination of a language i've created

pxeger

03:36

woah, does Proton have something like while comprehensions?

hyper-neutrino

nope

Bubbler

Doesn't look like a comprehension but just a while statement followed by an expression without separator

which is cursed

hyper-neutrino

yeah

you don't need to put semicolons, those are available for clarity

but if you put two statements next to each other it just assumes you meant to separate them

also if you put two expressions together in a function call it just assumes you meant them to be separate arguments because commas are also optional

pxeger

uh

emanresu A

Sometimes proton is better than JS or Python... Sometimes it's worse than both

hyper-neutrino

03:38

it's golfier when it works

n=>v=>((a=>[v,a])*n)([v]) i'm still quite happy with the way this works

pxeger

why is function multiplication a thing?

so is addition composition?

Razetime

it's very important

pxeger

Why did you replace your Jelly answer, and ignore caird's 4-byte suggestion?

hyper-neutrino

because neither my original nor the 4-byter were valid

lyxal

can't believe I just got recommended an elsa-gate style video on youtube

pxeger

03:50

@hyper-neutrino oh

emanresu A

04:19

CMC: Most irrelevant xkcd

(No using xkcd.surge.sh)

hyper-neutrino

a relevant xkcd would be irrelevant here because you asked for irrelevant xkcds, and an irrelevant xkcd would be what you want and therefore it'd be relevant.

emanresu A

Great, I've been paradoxed

Redwolf Programs

04:43

You know you're in need of some organization when the only thing on your to-do list is "write to-do list"

emanresu A

Todo: Determine if my todo list is done.

Bubbler

05:03

Todo: Todo: Todo: Todo: Recursion limit exceeded

lyxal

Dec 13 '20 at 4:57, by Lyxal

note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "note to self: make a note to self saying "...

Bubbler

Lol, ninjad by a year and a week

lyxal

I am speed

Redwolf Programs

05:36

Today I made a crossbow in minecraft that shoots donkeys instead of doing something productive

2

See I meant to make it shoot dragon fireballs but I hit enter too early on the autocomplete

hyper-neutrino

lol, nice

Wolgwang

07:27

Uhm I want to ask a question on code golf.SE

:)

lyxal

Make sure you use the sandbox to get feedback from people to help iron out any flaws

PyGamer0

08:07

i hate school

Wolgwang

@PyGamer0 I just came from school Bruh.

PyGamer0

even me lol

lyxal

08:25

Haha imagine having to go to school

4

emanresu A

Summer holidays go brr

PyGamer0

oh wait you live in NZ

my winter holidays is a week away :/

Sandbox Posts

0

A: Sandbox for Proposed Challenges

Dumbo octopus flashing time code-challenge Day 11 of this year's AoC was about a grid of bioluminescent dumbo octopi. I'll try to explain how this works, click on the link for a better explanation. You have a 10x10 grid of octopi which slowly gain energy and flash when fully charged. Each octopus...

emanresu A

@PyGamer0 Yeah, summer holidays are a bigger deal here - they're as long as your winter holidays (I think)

pxeger

@PyGamer0 in the UK I'm pretty sure school holidays started at the end of last week

are you in a country that doesn't widely celebrate Christmas?

because to have holidays starting on xmas day would be very weird here

Niko

08:54

I may not even have winter holidays because i didn't pass my chinese :(

emanresu A

09:14

8

Q: Why is stock market crash so bad?

Many folks speak about potential stock market crash when central back raise interest rates. I am not a graduade economist nor I pretend to understand it, but I am definitely curious about whats happen because it affects me. A lot. I have two questions: Why FED/ECB/whatever raising interest rate...

macroeconomics stock-market

Hm, wonder why... /s

Razetime

50 rep for the first BQN answer here from a newbie

emanresu A

Does BQN have a matrix multiplication builtin?

pxeger

that feeling when you spend ages trying to golf a program, and produce like 20 variants, all of which are the same length and no shorter

Razetime

@emanresuA mlochbaum.github.io/bqncrate/?q=matrix%20product#

PyGamer0

09:43

@pxeger for me holidays start from 24th

and it is for 1 week

i think its my school cause my friend's holidays have started

but another friend has exams currently

@emanresuA 1 week?

are you spying on me irl?

emanresu A

I was just guessing, and wrong

(Our winter holidays are two weeks)

pxeger

I am confusion

2

New Zealand eggsplain

PyGamer0

@emanresuA my summer holidays were 2 months (when i was smol)

now its gonna be a single month

emanresu A

We have 2-week holidays between terms, 6-week summer holiday from mid-dec to end of jan.

PyGamer0

@emanresuA 6 weeks o_o

which grade are you in?

emanresu A

09:53

High school

pxeger

@cairdcoinheringaahing I'm pretty sure the Nile exists

PyGamer0

@emanresuA i meant exact number

isnt rwp in 10th?

Oct 8 at 4:29, by Redwolf Programs

I'm in 10th grade now, so just over two and a half years.

pxeger

@pxeger (and last I checked, it was in a liquid state)

PyGamer0

i am pretty sure there are 69 states of matter

emanresu A

@PyGamer0 10th grade in america is different from year 10 here :P

PyGamer0

09:58

wat

wtf

whytf

emanresu A

Education in New Zealand

The education system in New Zealand is a three-tier model which includes primary and intermediate schools, followed by secondary schools (high schools) and tertiary education at universities and polytechnics. The academic year in New Zealand varies between institutions, but generally runs from early February until mid-December for primary schools, late January to late November or early December for secondary schools and polytechnics, and from late February until mid-November for universities. In 2009, the Programme for International Student Assessment (PISA), published by the Organisation for...

I need sleep, o/

PyGamer0

o/

ok so i give up, i think age is the better option to compare

Wolgwang

10:16

Do the questions on code golf generally receive so many upvotes?

lyxal

@emanresuA same here except sometimes it was 3 weeks between terms

Jo King

11:17

@Wolgwang relative to...?

Wolgwang

@JoKing Most of the SE sites

Jo King

i think so yeah. At the very least, they recieve more answers, and there's a core set of users for which pretty much all questions are relevant

i don't really participate on the other sites though, but just having a look now, i see a lot of 0-1 upvote questions

Sandbox Posts

11:51

0

A: Sandbox for Proposed Challenges

Schrödinger's cat program When first run, the program will have a 50/50 chance of doing the following: A cat program A standard cat program: read STDIN and put it on STDOUT. Nothing (no-op) The programs just halt (the cat is dead). The behaviour is permanent: Once the program choose between the t...

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