The Nineteenth Byte

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1:33 AM

Q: Write a function that returns an iterable object of all valid points 4-directionally adjacent to (x, y)

A very common need in algorithms classes and computer science in general is to iterate 4-directionally over a grid or matrix (such as in BFS or DFS). This seems to often result in a lot of clunky and verbose code with a lot of arithmetic and comparisons within loops. I've seen many different appr...

2 hours later…

Unrelated String

4:02 AM

I managed to come up with a 4-byte Brachylog solution to the alphabet challenge with such strange I/O that it isn't even straightforward to run it from interactive Prolog

This takes an unbound variable as the input variable, and a two-element list containing the input and output as the output variable. You'd think that would sort of make sense as being run as run_from_atom('Ṇi₁p',_,[Input,Output])., but that doesn't even work, it just fails for some reason, so it has to specifically be run_from_atom('Ṇi₁p',_,Z), Z=[Input,Output].

Needless to say I'm not comfortable submitting that as an answer lol

Erik the Outgolfer

4:20 AM

@xnor hey, 'grats for 100k! :D

El'endia Starman

Congrats xnor!

Meanwhile, Dennis is a measly 7k away from 200k. :P (And the next closest to 100k is at 92.4k.)

xnor

4:50 AM

@EriktheOutgolfer Thanks!

Anonymous

@UnrelatedString Sounds like you just need to propose it on the meta thread /s

PhiNotPi

An ad I found on some online marketplace: "AMD Phenom II x6 1065T (1 broken pin) $30" hmmmmmm

At least they're honest about having a broken pin on the CPU. Overall, these sorts of marketplaces/craigslist-type websites are an interesting mixed bag of people either undervaluing perfectly good stuff or overvaluing completely broken obsolete stuff.

John Dvorak

5:15 AM

@PhiNotPi Brand new family car, never used, slightly dinged in transport

DJMcMayhem

5:56 AM

@EriktheOutgolfer Someone should make a challenge themed around the XNOR operation in honor

Adám

Wonder which languages have built-in XNOR.

CMC: Given two probabilities, answer the total probability that either both happen or neither happen.

John Dvorak

6:12 AM

->p,q{1-p-q+2*p*q}

I suspect that the vast majority of languages has an XNOR builtin

Adám

@JohnDvorak I'm not certain about that, and certainly not one for probabilities.

John Dvorak

You didn't say "for probabilities"

irb(main):005:0> (0..3).each{|i| p [i[1] == 1, i[0] == 1, (i[1] == 1) == (i[0] == 1)]}
[false, false, true]
[false, true, false]
[true, false, false]
[true, true, true]
=> 0..3

ais523

6:39 AM

@UnrelatedString it works fine from within Brachylog: Try it online!

although that's probably because Brachylog doesn't inline structure constraints like Prolog does, come to think of it

flawr

@Neil Well I don't think it is you who is missing a } :P

thanks, that must be the mistake

ais523

IIRC Brachylog does inline variable references, though, and it still works when we specify the structure using a variable: Try it online!

flawr

@xnor oh nice, congrats:)

How is your brother @xneither doing btw?

Unrelated String

7:02 AM

Yeah, I had the Brachylog testing header on the link set up and it worked fine, but it's still weird that it won't work in Prolog unless you unify the output variable with the list after running the Brachylog

Time to spend the next hour researching structure constraint inlining lol

Fatalize

8:06 AM

@UnrelatedString Are you not working on your language anymore?

Unrelated String

8:44 AM

Just sorta not actively making progress

Lots of things I could do with it and haven't quite decided what

Fatalize

9:16 AM

I see

3 hours later…

Veskah

12:25 PM

Intradesting, Both Luis Mendo and new guy roblogic have Boba Fett as an avatar.

AdmBorkBork

1:01 PM

Any remaining thoughts before I post this?

Fatalize

@AdmBorkBork I’m not sure if the "output in ascending order" constraint is really necessary?

flawr

@AdmBorkBork same ^

AdmBorkBork

That's a good point. It'll just add a sort to the end anyway. I'll remove it.

Veskah

@AdmBorkBork [2,3], 5 would produce an empty output, right? Should that be covered?

AdmBorkBork

That would output [2, 3].

Veskah

1:11 PM

Oh, misread. It only needs one in the list. Was thinking it needed all of the primes

(Also, didn't think through any test cases on account of every example showing that wouldn't be the case)

(:'DDDD)

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Q: Some Prime Peerage

(Randomly inspired by https://mathoverflow.net/q/339890) (Related: 1, 2) Given an input list of distinct prime numbers (e.g., [2, 5, 7]), and a integer n, output all positive integers strictly smaller than n that contain only those primes as divisors. For input [2, 5, 7] and n=15 this means an o...

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2 hours later…

New Main Posts

2:56 PM

Q: Output a Super Mario Image

This is a problem on Luogu OJ. I decided to post it here because on Luogu OJ, many people, including me and my friend, are interested about how to solve this problem within the fewest character. Sorry if it is not a good challenge here. Your task is to output the following ASCII-art: ...