The Nineteenth Byte

3:53 AM

0

Q: Find the missing number in a range of numbers

Question: Given a String s of randomly-shuffled numbers from m to n such that -100,000 <= m < n < 1E9, your job is to find the number that is missing from the group. Note that the string can be randomly-generated, and the below cases are only an example of what that string may be. This input mean...

Redwolf Programs

Winter bash time!

Bubbler

and AoC is coming again

Razetime

4:12 AM

@RedwolfPrograms can phones even handle that amount

Redwolf Programs

Definitely not

Bubbler

meanwhile, just solved a PE problem after n years of inactivity

the most satisfying moment in this year

Razetime

Project Euler?

Bubbler

yes

Redwolf Programs

4:31 AM

Why did a post I edited three minutes ago get sent to me in the VLQ queue by the system...

Razetime

@RedwolfPrograms don't trust the system

Redwolf Programs

More like the system doesn't trust me I guess

pppery

More like the system doesn't like code-only answers with no explanation.

Even the community user doing CommonMark migration caused low quality post reviews.

And the system can't not trust itself.

Redwolf Programs

That is the basis of any good system

But I get what you mean lol

pppery

It's the basis of any good system to distrust itself?

HyperNeutrino

4:36 AM

sort of. i think any good system should enforce consistent policies even if it invalidates itself

like i think the system should ideally be consistent across all parts, so community shouldn't cause VLQ

but if community does something that another user would trigger VLQ on, the VLQ detection should report it even if the system itself did it

Redwolf Programs

4:50 AM

10m to AoC

HyperNeutrino

9m to AoC

Redwolf Programs

8

7

6

5

pppery

4

3

Redwolf Programs

3

ASCII-only

get ready for me to get rank 100k

pppery

4:58 AM

2

2

time to choke again

same

1

.5

4:59 AM

0

Lyxal

ugh

yucky input

204 p1

eval ftw

HyperNeutrino

2/3

wow

wew

wow part 2 is hard today it seems

oof i missed rank 1 by 41 seconds

Lyxal

no, it just takes a bit of thought

HyperNeutrino

could've saved that if i did the correct approach initially :/

part 1 by 18 seconds, idk if i made a mistake that could've gotten me there or if i just got beaten by a better opponent

either way, can't be disappointed, lol. seems like 1/1 was so close yet so far, but i'm happy with today's result

ASCII-only

5:15 AM

:( part2 i cant do

HyperNeutrino

oof

ASCII-only

lel rank 110

part 2 needs sets that was the problem.

disgusting.

oh well, rank 110 is more than i can ask for

Unrelated String

lol

HyperNeutrino

oh yeah python sets are OP for stuff like this

ASCII-only

>:(

HyperNeutrino

5:27 AM

python is imo one of the better languages for aoc

complex numbers for coordinates

sets for stuff like this

Razetime

I feel like I got p1 right

but I cant find anything wrong with my answer

Redwolf Programs

I can't figure out why my p2 is wrong and there's no useful test case this time

sets

What do you mean

er nothing

5:36 AM

369/609 poggish

ASCII-only

or more like you cant just do indices_for_properties[property] = indices.first(valid for x property)

Redwolf Programs

I just got an array assignment backwards because I use one letter variable names for this and my brain just turned into types of pasta we have no name for

Lyxal

@anyoneWhoSolved is this the right order of the fields?

Redwolf Programs

It probably varies per person

HyperNeutrino

I don't have the same order

Lyxal

5:38 AM

oh

HyperNeutrino

my friend and I have literally identical inputs today

Lyxal

I'll look at it later probably

Unrelated String

I feel like I should not be brute forcing through 2432902008176640000 possibilities

hmmmmmmm

HyperNeutrino

...

have a slight idea that might not work too well

Unrelated String

yeag

Bubbler

5:48 AM

Today's part 2 has multiple possible approaches but only one works very well I guess

1983/1113, started late but managed to write a 10-line function in Factor successfully

Unrelated String

i'm currently trying to narrow the field down for each index then work from there but it doesn't seem like it's narrowing enough

it's definitely narrowing to some extent because 104857600000000000000000000 is a hell of a lot bigger than 2432902008176640000 but they're both pretty damn big

HyperNeutrino

wait how are you getting that many cases

Unrelated String

shitty mixed base conversion that i wrote on the assumption that it wouldn't have half that much to check

Bubbler

There is a clear pattern in the possible mappings between column ranges and data columns, if you visualize it well

Unrelated String

@Bubbler ...I could try that

HyperNeutrino

5:53 AM

i recommend printing out the possible slots for each field name and then seeing how you can get it in O(N^2) from there

Bubbler

It's O(n^k) with sufficiently small n and k, so it is expected to finish instantly with the right approach

Dec 9 at 5:41, by Bubbler

I'm waiting for the moment the difficulty skyrockets, so I have a better chance of higher rank

I didn't mean this kind of difficulty, I want some more mathy challenges >:(

HyperNeutrino

oof

this sort of stuff is perfect for me cuz i can speed code a bunch of silly ad hoc stuff that doesn't need to be hyper-optimized

Unrelated String

lol

wow, can't believe I got a rank as not-completely-awful as 2009 after more than an entire hour

...after getting 207 on part 1

HyperNeutrino

it was a rather annoying prob lol

Lyxal

6:08 AM

Is it a fair assumption that only one "column" of other tickets correspondes to only one rule?

Unrelated String

I don't know why it took me this long to realize that there has to be only one possible arrangement, and that there's no other constraints to consider

@Lyxal assumption? that's a given lol

HyperNeutrino

is it possible for a set of constraints to be reducible but have no field have exactly one valid slot

Unrelated String

if there was no single slot that only satisfies one field's constraint then there would be no unique assignemnt of fields to slots

Lyxal

My idea is that for each field, identify the column where all numbers fit the rule. Then, sort by that index

New Sandboxed Posts

0

A: Sandbox for Proposed Challenges

The Missing Number arithmeticcode-golfnumber Question: Given a String s of randomly-shuffled numbers from m to n such that -100,000 <= m < n < 1E9, your job is to find the number that is missing from the group. Note that the string can be (and generally is) randomly-generated/constructed, and the...

Unrelated String

6:11 AM

so if you had something like that then you'd just have to try the multiple possibilities lmao

Razetime

YES

I got it

Lyxal

@UnrelatedString but would it theoretically work?

Unrelated String

@Lyxal I doubt your input was constructed to admit multiple mappings

Bubbler

It could be solvable without getting the exact mapping because you just need to identify destination-columns and the rest

but then the difficulty really skyrockets

(or gets easier?)

(because then you can get a valid mapping out of gazillion possibilities by brute force and get the answer from that)

Razetime

it wasn't that hard to figure it out once you know set intersection is useful

HyperNeutrino

6:16 AM

i just used O(N^2) set differences lol

Razetime

thankfully this didn't give me a WS FULL

HyperNeutrino

CMC: Find two finite sets A and B with a bijection F : A -> B such that there exists a mapping M from A -> P(B) such that |M(a)| >= 2 and F is a unique bijection such that F(a) in M(a) for all a

i am not sure it's possible, but i haven't proven it's impossible yet

Bubbler

I think it's impossible for |M(a)|=2

Induction on |A|. If |A|<=1, M trivially does not exist. If |A|=2, the only possible M is each value of A being mapped to the entire B, so F is not unique.

For |A|=n≥3, pick a value a of A and let M(a) = {x,y}. If M(b) ∩ {y} = empty for all b ≠ a, F(a) = y is fixed, but then there must be an F' and M' going from A-{a} to B-{y}. Contradiction.

HyperNeutrino

6:36 AM

oh, that's a nice proof

okay. i had a feeling it wasn't possible; intuitively felt like it

Bubbler

Otherwise, pick another value b of A so that M(b) = {y,z}. If x=z, F is not unique. So x≠z, but then there must be F' and M' going from (A∪{c})-{a,b} to B-{y}

HyperNeutrino

hm

Bubbler

(you can substitute two mapping pairs M(a)={x,y} and M(b)={y,z} to M'(c)={x,z})

HyperNeutrino

i'll need to look that over a bit more, brain is not working too well rn and when it does i need to keep working on my final assignment

Bubbler

The last step is probably not rigorous

fixed version: If there does not exist a pair M(a) = {x,y} so that M(b) ∩ {y} = empty for all b ≠ a, every element of B appears exactly twice in M. Then we conclude that {x,y} is part of a cycle, which makes F non-unique.

New Main Posts

7:14 AM

1

Q: Help me compress this song

in my country we have a children's song which goes like this: Priletela muha na zid, muha na zid, muha na zid. Priletela muha na zid, muha na zid. Pralatala maha na zad, maha na zad, maha na zad. Pralatala maha na zad, maha na zad. Preletele mehe ne zed, mehe ne zed, mehe ne zed. Preletele mehe...

code-golf string kolmogorov-complexity

Adám

9:59 AM

@HyperNeutrino Can you give chat.stackexchange.com/users/490615/user14835830 access to chat.stackexchange.com/rooms/52405/the-apl-orchard ?

Neil

11:26 AM

@RedwolfPrograms got your hat on yet? I guess I need to reload the chat room to see hats here?

New Main Posts

1:06 PM

0

Q: Is there a more concise way to use the Santa emoticon [}:]>* programatically in a raku one-liner

raku -e 'sub santa($x is copy){$x~~s/ <[}:]>* /claus/; $x.say}; santa(":")' #OUTPUT claus Merry Christmas to one and all (and any)

perl

New Sandboxed Posts

1:19 PM

0

A: Sandbox for Proposed Challenges

Animal-Alphabetical Sequence The Animal-Alphabetical Sequence is an infinite string of letters built accordingly to the following procedure: Start with the letter A; Replace each letter with the name of the animal starting with such letter in the table below; Go back to step 2. For instance, th...

Redwolf Programs

@Neil I'm waiting for an interesting hat to put on :p

榨菜

if someone have feedback for Equality up to Swapping tell me please, first question

Razetime

@榨菜 I'm not very well versed on the math notation, but it looks good

榨菜

but you can understand it? it's difficult to describe with

words

Razetime

not very well, no

does anyone know how to use PMA/Snails?

New Main Posts

1:31 PM

0

Q: Equality up to Swapping

inputs / outputs your program/function/routine/... will be a predicate on two tuple sequences; call it relation ≡. for the purpose of simplicity we use natural numbers: the input will be two list of pairs of numbers from ℕ (including 0); call them Xs and Ys the output will be a "truthy" value s...

code-golf array-manipulation decision-problem

榨菜

@Razetime :(

you compare lists with (a,b) in it for equality. but you don't care about order of (a,b)s

you can permute the (a,b)s by swapping except you can never swap (a0,b0) and (a1,b1) if a0=a1

Redwolf Programs

What the heck, someone just invited me to a "Room for ___ and Redwolf Programs", and I checked and they have like 10 for other people

Neil

@RedwolfPrograms huh, I already have a secret hat for some reason

Razetime

1:49 PM

@Neil it's the one you get for wearing a hat on any site

Redwolf Programs

You get a hat for wearing a hat? My head hurts.

Neil

@Razetime thanks

@NewMainPosts this tab keeps confusing me into thinking there's a new question

New Main Posts

3:12 PM

2

Q: Count how many times your program repeats

Your task is to write a program or function. It's output/return value must follow these rules: The program outputs 1 The program repeated n times outputs n The program backwards outputs -1 The program backwards and repeated n times outputs -n A mix of forward and backward programs will output nu...

code-golf source-layout

Rahul Verma

3:29 PM

@NewMainPosts Is this question about checking if the same set of points are in both array? Just shuffled in each array..

HyperNeutrino

@Adám done

Adám

Thanks!

Razetime

4:15 PM

contemplating on whether it is worth my sanity to make a brainfuck interpreter in Husk

caird coinheringaahing

4:40 PM

@NewMainPosts Can someone explain why this isn’t a dupe of all of the other “compress this song” challenges before I find one to VTC?

Oh cool, when did hats start?

Redwolf Programs

Yesterday

caird coinheringaahing

> Snaphat
Answer in 30 minutes, +3 and accepted

That's not going to be awarded here :P

Redwolf Programs

First thing I thought :p

caird coinheringaahing

Does anyone else have the Cordovan hat? I haven't properly been on the site for a few days and it just tells me it's a secret aht?

Also, yay, my badge count is 5, 50, 150 :D

Redwolf Programs

Nice!

user

5:31 PM

I've got the Cordovan hat too (I'm wearing it). Not sure what triggered it, though.

Razetime

5:45 PM

@cairdcoinheringaahing now to find an excuse to make a challenge based on that

Redwolf Programs

Is there a challenge where you take a list like [2, 4, 1, 6] and return a list where each item is repeated n times, where n is the previous number ([2, 2, 2, 2, 2, 2, 4, 4, 1, 1, 1, 1, 6])?

caird coinheringaahing

6:03 PM

@Razetime Given n (5) and m (150), output whether it is possible to get from n to m by appending or pretending a single digit at a time

Redwolf Programs

7:23 PM

CMC: Take a list of positive integers, and return a list containing each of those numbers repeated a number of times specified by the previous number...basically the same as my above comment

Example: [2, 4, 1, 3] -> [2, 2, 2, 4, 4, 1, 1, 1, 1, 3]

Wezl

so it wraps around? [1, 2] -> [1, 1, 2]?

Redwolf Programs

Yes

Adám

7:41 PM

@RedwolfPrograms APL (dzaima/APL), 6 bytes ⊢⌿⍨¯1⌽

¯1∘⌽⌿⊢ works too.

Wezl

8:04 PM

done. It's not 6 bytes, but it's readable :ſ

Adám

@Wezl You find the APL code hard to read?

Wezl

not for apl code, but yes for english

Adám

If you read the APL symbols as English words, it is pretty neat: ⊢self ⌿replicated ⍨by ¯1⌽one-step-left-rotation.

Wezl

but you have to know how replicate works

Adám

@Wezl Or seen from the other side, you have to know what the English word replicate (or repeated) means.

Wezl

8:20 PM

if I showed it to someone in my family, they'd think it was mojibake, not code. But I surrender that it is very readable for APL and lisp is too parenthesised

Adám

@Wezl Ask them what's more readable of ×/n-2×¯1+⍳⌈n÷2 or

wizzwizz4

@Adám The graphical representation is almost always going to be clearer.

That doesn't mean it's optimum; a graphical representation of APL would probably beat both.

Something meaning “reduce with ×” is always going to be easier than “capital Pi”.

Adám

wizzwizz4

@Adám … No.

Wezl

@Adám the phi, macron, /, and unmatched floor/ceilings are going to confuse someone who knows traditional math notation

Adám

8:35 PM

@Wezl Sure, but that's because they already know those. Which do they think would be easier to learn and use?

wizzwizz4

The graphical mathematical notation has four clear sections.

dzaima

@Adám i'd say the 2D nature and clearly separate structures work in favor of traditional math notation, rather than against it here

Wezl

@Adám out of TMN and APL?

Adám

@Wezl Yeah.

@wizzwizz4 Yeah, it is actually interesting that TMN uses ∏ but e.g. ⋀ and ⋂. Why not use ⨉?

wizzwizz4

@Adám Historical reasons.

When APL starts pushing 200 years of radical change in which parts of maths people are interested in, you'll understand.

Adám

8:43 PM

Oh, already after 50 years, APL has issues, and it is high time for a rethink.

Redwolf Programs

9:52 PM

I'm 100 away from top 25 in winter bash hat game

Wezl

@RedwolfPrograms where are the rankings?

Redwolf Programs

Leaderboard, linked under the play button

I'm top 20 in play time for suffering through 20 minutes of this

New Main Posts

10:19 PM

0

Q: Model Checking, verification

Build a model for the counter that counts the number of times a variable has the value 1 modulo 8 with binary variables in GCLang. In other words, one of your variables should be a free variable, and the transitions of the counter should depend on the value of this free variable. Keep in mind th...

logic

Newly Featured Questions

10:33 PM

81

Q: "99 Bottles of Beer"

Write a program that outputs the lyrics to 99 Bottles of Beer, in as few bytes as possible. Lyrics: 99 bottles of beer on the wall, 99 bottles of beer. Take one down and pass it around, 98 bottles of beer on the wall. 98 bottles of beer on the wall, 98 bottles of beer. Take one down and pass i...

code-golf string kolmogorov-complexity

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