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12:20 AM
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A: Sandbox for Proposed Challenges

FlipTackSource Code Inflation Your task is to write a program which, when run, outputs a longer program. This longer program should in turn output a longer program, and this should continue indefinitely. For example, the Pushy program: 95&34_" Outputs the following: 95 95 34 __" Which in turn out...

 
12:37 AM
 
12:55 AM
2
Q: Should the Info Box Link to the Active Sorted Sandbox?

0																												'The link to the sandbox in the info box is nice, but I was wondering if it might be better to link to change the target of the link from https://codegolf.meta.stackexchange.com/questions/2140/sandbox-for-proposed-challenges to https://codegolf.meta.stackexchange.com/questions/2140/sandbox-for...

 
1:07 AM
@WheatWizard Very nice, I didn't think about creating the letters numerically. Pity about those extra rows of .s though
 
 
1 hour later…
2:21 AM
0
A: Sandbox for Proposed Challenges

xnorJoin two file paths A file path consists of letters a-z separated by slashes /. Your task is to join two paths as follows: If the second path doesn't start with /, concatenate them with exactly one / in between. If the second path starts with /, just output it. For example, /User/Desktop ...

 
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Q: Make a Lost Compass

Wheat WizardLost is a 2-Dimensional programming language where the instruction pointer starts at a random location, moving in a random direction. A description of the language can be found at the bottom of the post for completeness' sake and a tutorial for the language can be found in the above link. The t...

 
3:22 AM
1
A: Sandbox for Proposed Challenges

Andrew EpsteinFor any integer a and any positive odd integer n the Jacobi symbol is defined as follows: $$ \left(\frac{a}{n}\right) = \left(\frac{a}{p_1}\right)^{\alpha_1} \left(\frac{a}{p_2}\right)^{\alpha_2} \cdots \left(\frac{a}{p_k}\right)^{\alpha_k} $$ where $$n = p_1^{\alpha_1}p_2^{\alpha_2}\cdots{p_k^{...

 
 
4 hours later…
7:46 AM
 
 
3 hours later…
10:33 AM
huh, I never realised at the time, but Explain XKCD points out that Star Wars: A New Hope is actually a homage to The Dam Busters!
 
 
3 hours later…
done
 
Thanks.
 
2:41 PM
1
Q: Fill the Golfeek gutter

ArnauldGolfeek is the working name of an esolang I'm occasionally working on. One distinctive feature of this language is that each statement is encoded as a sequence of bits rather than a sequence of bytes. Instead of just showing a long binary sequence, the 'gutter' of the source editor contains a re...

 
@EsolangingFruit Is that rms?
 
3:27 PM
@xavierz legalese is just a very strange programming language. If your code-spideysenses go all tingly reading it they it is probable someone forgot their version of a semicolon somewhere. Trust your intuition. — Borgh 7 hours ago
 
4:03 PM
RIP my laptop...I've had an Acer Chromebook 11 for three years, tried to turn it on today and the only thing that happened was the status light rapidly flickered a dull whitish color...
 
@RedwolfPrograms Battery?
 
Maybe
The only issue I'd noticed up until that point was that it turned off randomly twice in the last few days, but I assumed that was from not restarting it often enough
 
4:54 PM
Any feedback on this challenge?
 
@cairdcoinheringaahing That's a cool idea
Looks extremely difficult, but probably clear enough
 
@DJMcMayhem Thanks! I'm planning on extending it to a bunch of different options (image processing, multiplayer etc.)
 
 
1 hour later…
5:57 PM
CMC: Take a given matrix M=[a b; c d]. Is it always possible to add a real value x to each element (M = [a+x b+x; c+x d+x]) to make M singular?
 
No. Take {0 1 | 1 1} as an example.
 
@JohnDvorak Wouldn't adding -1 to each value work? {-1 0 | 0 0}
 
good point
Then it's always possible, at least with real a, b, c, d
 
6:12 PM
All you need for it to be singular is for there to be a real number y such that y(a+x) = c+x and y(b+x) = d+x, correct?
 
(a+x : b+x) = (c+x : d+x)
(a+x)(d+x)=(b+x)(c+x)
(a+d)x + ad = (b+c)x + bc
(a+d-b-c)x =bc-ad
 
I think so long as (b+c) =\= tr(M), x exists
I.e. the sums of the diagonals aren't equal
 
ah, true
 
So M = [1 0; 1 0] would fail
 
that one's already singular
m = {2 1 | -1 -2}
 
6:18 PM
Yeah, that should work (i.e. be impossible)
 
@DLosc yes I meant reading from stdin, I believe I had the 'sum numbers from stdin' challenge in mind when I asked about it, sure I will use functions
I really like tinylisp's minimalism, maybe I'll write a tinyprolog in tinylisp :)
 
6:38 PM
to increase participation in sed, I am awarding 200 rep to the shortest sed solution that solves fizzbuzz codegolf.stackexchange.com/q/58615/41805
5
(inspired by the discussion on bounties yesterday)
 
@JohnDvorak In that case, isn't x = 0? still works
 
@ ROs could you please pin my bounty message chat.stackexchange.com/transcript/message/52976802#52976802? it's only 7 days so I would like to increase awareness
CMC: get the penultimate character from a string (it can contain newlines)
 
@KritixiLithos I won't pin probably, but I can offer you a star
 
thank you, that's should be good enough now that chat doesn't see many stars
 
@KritixiLithos Python, lambda s:s[~1]
 
6:53 PM
do you want to try in sed?
 
Never used sed before :P
 
if you want to start learning, gnu.org/software/sed/manual/html_node/index.html is a good place, in this challenge, all you need is a single substitution, and forgot to mention, with the -z flag, you can slurp all input, including newlines, into the "buffer" (technically "pattern space")
 
If the string doesn't contain newlines, vim could do: $XVp for 4 bytes
 
that's why I added that :P makes it more interesting for vim
 
Brain-flak: 8 bytes. (Not revealing yet so other people can figure out, it's pretty simple)
 
6:58 PM
[brute-forces all the 8-byte Brain-flak programs] :P
 
Surely it would be easier to check the docs and figure it out :P
4 atoms
 
Who said anything about easier???
 
I got 20 in brainflak
 
Can I see what you have? You're probably making it harder than necessary
 
7:07 PM
Oh, huh I guess I forgot the order things are pushed in
At any rate, -r makes it a lot easier
 
@DJMcMayhem I was wondering about that!
I'm pretty sure I got your intended 8-byte solution.
 
Yep
 
so how would you golf it without the -r flag?
 
I think your solution is optimal. I'll try a few things to see if I can beat it
 
also gtg, but an imaginary cookie to the one who solves the cmc in sed -rz with 10 bytes
 
7:16 PM
sqrt(-cookie)
 
@cairdcoinheringaahing Introducing: The ICookie from apple
 
It tracks when and where you eat it!
 
@KritixiLithos Yeah, I think that's optimal
BFMC: Cumulative sum of an array
52 bytes
 
7:34 PM
As in [1, 2, 3, 4] -> [1, 3, 6, 10]?
 
Yep
 
I'm not sure how to set up the framework for this problem on TIO.
 
Excellent, thank you! I'm guessing the -c flag specifies that input and output are characters?
 
Yep
 
7:43 PM
@DJMcMayhem BFMC?
 
Sorry, BFMCTCBDIALIYRW
Brain-flak-mini-challenge-that-can-be-done-in-any-language-if-you-really-want
 
Wow, I got most of those words. :D
 
8:41 PM
@DJMcMayhem 54 bytes and the cumsum array is reversed. tio.run/##SypKzMzTTctJzP7/…
Still, for being a complete newbie to Brain-flak, I'm pretty happy. :D
 
Nice! I'd have to expand that before I could offer tips lol
 
Do you have any tools for debugging, like perhaps something that shows the stacks at each step?
 
Not really...
@El'endiaStarman (()[()]) --> (<()>)
 
Oooh, of course.
 
2
Q: Even and Odd Numbers

Jono 2906Sandbox Adapted from exercise 4 of 100 little Keg exercises The ability to repeat chunks of code within a program is an important part of any programming language. Also just as important is the ability to make decisions based on different values. The Challenge I want you to write a program t...

 
8:46 PM
Hmm, forgot to save my solution. I guess I'll rewrite it lol
52 bytes: Try it online!
 
@DJMcMayhem 28 bytes: {({}<>({}))<>}<>{({}<>)<>}<>
 
30 if the inputs are strictly positive: Try it online!
 
Oh, I forgot about 0s
 
Oh, duh 28 if it's strictly positive
@H.PWiz That's exactly what I had except I put an extraneous {} in there
 
Took a bit of thought to understand ({}<>({})) but that's a really neat trick.
 
8:59 PM
Yeah, it's really convenient that it gives a 0 the first time, so you don't have to preface it with <>(<()>)<>
Or (<>)<> I suppose
 
I wonder if this is one of the simplest challenges that forces you to use the "third stack" (memory).
Computing 2^n might be simpler.
 
2^n is a fun one
@El'endiaStarman I would argue that nearly all brain-flak snippets use "The Third Stack". Or to be more specific, all brain-flak snippets that use a monad (...)|{...}|[...]|<...> use The Third Stack
 
@El'endiaStarman Nice! Now can you do it without <>?
 
@DJMcMayhem Technically, yeah, but cumulative sum requires non-trivial Third Stack usage.
Very cool. 32 bytes again, no <> (but two <...>): tio.run/##SypKzMzTTctJzP7/X6O61kZDQ1PTTrMawqyu1QQiu2gNzVjN2ura//…
 
Yeah, the ({}<(())>) is very obnoxious. I assumed the one-stack approach would be shorter but that ruins it
Wait a second...
Hmm, well 2^n-1 is slightly more convenient: {({}<(({}()){}[()])>[()])}{}
 
 
2 hours later…
11:01 PM
0
A: Sandbox for Proposed Challenges

caird coinheringaahingMake a matrix singular Let $$M = \begin{bmatrix} a & b \\ c & d \end{bmatrix} $$ We can define a function \$\text{sing}(M)\$ as $$ \text{sing}(M) = x $$ where \$x\$ is the real number such that $$ \begin{vmatrix} a+x & b+x \\ c+x & d+c \end{vmatrix} = 0 $$ Your task is to take a \$2\text...

 
11:28 PM
Any feedback for this, this, and this sandbox challenges?
 

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