Reverse Deltas of an Array
A continuation of Inverse Deltas of an Array
Your task is to take an array of signed 32 bit integers, recompile it with its deltas reversed.
Example
The List,
18 19 17 20 16
has the deltas:
1 -2 3 -4
which, when reversed, yeilds:
-4 3 -2 1
...
Am I wrong in thinking that half of the answers for these golfing languages could be autogenerated from one of the other golfing languages with a cunning regex bot?
compiling between CJam and Jelly via regex is probably impossible, for example (unless you use a Turing-complete regex variant and write at least a parser and deparser)
because CJam is fundamentally stack-based and Jelly fundamentally isn't
also they tend to differ in which primitives they have
however, all the golfing languages tend to be good at the sort of trivial problem that's very common on PPCG, and the solutions will all likely use the same algorithm in those cases
in the case of this problem, the golfing languages will all likely use an algorithm along the lines of "take deltas, reverse, prepend first element of the input, take cumulative sum"; however, the "prepend first element of the input" step may look very different in different languages as it's trying to refer back to something that already exists
My only knowledge of most of these languages is what I've read in some of the answer descriptions, but the stack based ones seemed to be very similar in concept. Even if they didn't have the exact same primitives I figured you'd at least be able to map a primitive from one language to a more complicated sequence in another.
@JamesHolderness maybe not with one regex but maybe with multiple it's definitely possible. Maybe not Cjam and Jelly but Pyth <-> Cjam or maybe even 05AB1E
The Stack Exchange network provides a good home for us, despite the fact that all of our rules and structure are basically a hack atop a normal SE site.
I have heard that the reason the i variable is used so much is because there was an old computer where each variable could only be a single letter and that reserved the variables a through h as internal variables, leaving i as the first one available to the programmer. This seems believable, as t...
just out of interest, how do you do "the head of a list, prepended to its deltas" in Jelly without a convenient reverse operation to help you out? I couldn't see a remotely short way
Ḣ;I doesn't work because Ḣ modifies the list
(and it wouldn't generalize to Ḣ;IU anyway because that parses incorrectly)
@JamesHolderness An automated translation of CJam to Jelly should be rather easy under the right circumstances, but there are two things to keep in mind:
1. Jelly doesn't have access to anything but the arguments (up to two), the global arguments (rarely useful), the previous return value, and a register. CJam has an unbounded stack and 26 variables, so keeping track of intermediate values is a challenge in Jelly. 2. Jelly has a different set of built-ins and a different way of doing things, so an automated translation from another language will almost always be suboptimal.
@ais523 You could simply index into the list instead of using head, or you flup the arguments and use ;@ to restore the desired order. I'm not sure if there's a shorter way.
@EᴀsᴛᴇʀʟʏIʀᴋ When cubes are being dragged from one place to another, they relocate from the back to the front. Also, pre-placed cubes seem to have some sort of "respawn" attribute that is preserved when moved.
@ais523 That's actually where it really shines. Jelly frequently gets outgolfed in the simpler challenges, but it's rarely beaten in the more complicated ones.
(I also somewhat disagree with the way that you can cause the program to be parsed incorrectly by changing the number of command-line arguments it's given; that seems like it's a specific aim to exploit PPCG rules, rather than something that could be practically used, as the only way to make a practical Jelly program complain that it was being used incorrectly would be to write a polyglot; that's something of a different argument though)
I guess it's not really a problem because we use program-or-function rules
@ais523 That's a natural consequence of Jelly's links/functions behaving differently for different arities. J and APL (which Jelly is based on) also behave differently depending on how many arguments are passed to a tacit verb/function.
in most of those languages, though, giving the function the wrong number of arguments won't fundamentally change what it does
I often golf in Perl, where you have to pay a whole byte to declare that the program should take input, and two if you want it to input a matrix
which is much less than most other exoteric languages, making Perl very good for golfing
but still, the language doesn't implicitly figure out the input format based on what it can see, because then erroneous input would screw the program up much more dramatically than just giving a parse error at the appropriate time
in C, which has variadic functions, the function itself has to specify how many arguments it's expecting (although it can use arbitrary C code to work it out)
printf() needs to parse its own format string in order to request its arguments
in most other languages with variadic functions, they get a list containing all the arguments, and if they care about how many there are, they have to check the length of the list
Well, there's no doubt Jelly was made for golfing. (Yet, this particular behavior is also present in non-golfing languages.) You obviously don't write a good golfing language by imitating C.
on the basis that if you're being given an array of strings, maybe array and string-processing primitives are more useful than floating point arithmetic
by PPCG rules, it's fine, but as a language designer, I'm horrified
@ais523 i have noticed the same thing as one (out of a few) places where jelly really manages to shave off the last two bytes in competitive challenges
@ais523 I do think designing golfing languages is an interesting meta-challenge. Everyone can write a language with a gazillion built-ins and excel at the tasks covered by those built-ins, but combining them to do something more complex is a whole different story.
@ais523 Usually argument types and number of parameters can change to support polymorphism; the fact that the same function with different parameters does different things is... is this what gnaws on you?
@AlexA. well, the idea would be that you could get efficiency by not needing any sort of grouping operators or precedence or stack, though perhaps not as efficient as jelly custom-tailored combinators
@ais523 are you also against the python golfing technique of writing a function with an extra optional argument that's used just for recursing?
@ais523 That "problem" isn't unique to Jelly though. Most golfing languages have overloaded operators, so you have entirely different code depending on what kind of input is given to the program. Jelly only had a handful of overloaded operators.
@Dennis I guess I'd draw a line here: overloading operators is fine if you can determine at a hypothetical compile time which of the various overloaded operators would be used
@Dennis I feel that this lack of overloads really helped jelly because it allowed a lot of autovectorization and was in turn allowed by its full 256 code point ussage
well, in the recent Minesweeper challenge, I ended up submitting a highly practical Minesweeper solver
and it got highly upvoted, even though it was much longer than the programs that simply generated all possibly boards and checked them for correctness
(it turned out practical sort-of by accident)
the parser ended up being much harder to write, and more byte-costly, then the actual rules engine (which is one thing that really holds Prolog back from golfing)
That may be just me, but I don't vote up practical solutions to code golf contests (unless they also happen to be short), just like I wouldn't upvote golfed solutions to a fastest code challenge.
Not targeted at your answer (which I haven't read, and would probably not be able to judge anyway as I don't know the first thing about Prolog), but a high amount of upvotes can happen for almost any reason. I had to delete answers with 100+ upvotes because they were invalid.
For example, the answer below has a higher score than any single one of my answers.
right, I'm confused enough at my second-highest-upvoted answer getting so many upvotes (although it does win the challenge, by being a single byte long in a challenge where a zero-byte solution is unlikely)
that entry you linked clearly wins the hello world challenge, which is one of the most popular challenges there is
(to the extent that many golfing languages have hello world primitives)
Then again, voting on this site is rarely ever about how well golfed something is. My "Loading forever" answer is now my highest voted answer of all time (across all of SE), and udioica kicked my butt with a much more impressive answer that I can't even wrap my head around. He got almost no votes on it
I happened to post early, so now it's in the positive feedback loop
@Dennis but it encourages a feedback loop in which more useful answers will not necessarily rise about less useful answers; ideally each answer should have an equal opportunity to be voted on, otherwise one answer maybe upvoted due to being helpful, and a better answer may not be upvoted due to being buried (the same users would upvote it, but they don't see it)
it's even right at the top of the site if you visit it logged-out (something I do a lot, because I don't like leaving persistent logins around to sites I might visit by accident): "The best answers are upvoted and rise to the top"
but that's not true if nobody ever sees the best answers
Slashdot has the best voting system I've seen, but that's partly because voting is very limited, and a post from a well-regarded user needs just three upvotes to reach the vote cap (a new user will need four)
also users are encouraged only to vote on threads they aren't involved in
@Downgoat right, and how is it going to be fixed? you can't enforce a way of voting on people or penalize them for voting "incorrectly", unless irregular
I still find it hard to believe that a few programmers in their free time can make and implement a design faster than full-time designers at a multi-million dollar company
@Downgoat no, but I think @ais523 is talking about a language that is efficient as possible, on as wide a range of challenges as possible, within the bounds we set for ourselves
@ais523 the best solution would be to have a special answer submission form for PPCG and in that have an explanation box, if no explanation is given answer is shown towards bottom
but on a site where you can frequently cap rep by accident, the site design basically says that your worth as a user is measured by how often you can cap
@ais523 I understand that argument coming from someone with low rep, or someone right at a privilege threshold. It's a bit harder to hear from people with over 10k.
(this means that the site actively discourages you from doing anything to save a potentially dubious question, because if you fail, you get punished in the future)
that said, I'm the sort of person who tries to save questions anyway, even though I get punished for doing so
hmm, someone's submitted a cops-and-robbers cop in a language I can't find even with a search engine
which annoys me as I suspect it's trivial to crack, but have no way to verify that
and I assume the site's opposed to posting untested programs by guessing at the syntax of the language they're in
(this is another thing anagolf does better, it's totally OK with people doing that)
I don't see how anyone can complain about the quality of the site, yet refuse to give up a tiny portion of their rep to do anything about it. Granted, downvoting isn't the only answer (and won't fix everything), but if you're that stingy with them, then don't complain about a problem you're perpetuating.
@Geobits I guess from my point of view, it's more pointing out that the site doesn't give me an incentive to make it better, and in fact gives me incentives to make it worse; and that this is the same for other people too
Some posts have good arguments for either downvoting or not, sure. But when someone has next-to-no downvotes in their history and has been a member for a while, it's odd (to me anyway).
@Geobits why should I care about this particular site, though? I only came here because this is where the golfers are, and resisted joining it for months; from my perspective, I'd be better off if there was a max exodus of golfers to a better one
@ais523 You don't have to. I'm not saying you should or shouldn't care about this site (though obviously it would be nice if people did from my perspective). I assumed you did since you seem to have many ideas about how it could be improved, an are vocal about it. If that's not the case, I don't know what to say, because you can't convince someone that doesn't care.
question about the cops&robbers: does there have to be a way to do it for 31 sec within len/2 leveshtein distance? in other words, does there have to be a possible crack?
I ask this because the rules mention nothing about posting the crack when you declare your answer safe
@Dennis I think programmers rely on their knowledge of other languages to help them skim code from languages they've never seen before, but that doesn't work for golfing langs, even if they exhibit similar features inside, because the tokens themselves look completely different and are much denser
@Dennis Are you aware that Aheui isn't actually supposed to look like that? It's just that your system doesn't have the appropriate international fonts.
@Maltysen Right, but those use brackets to group the arguments of a single call. Not that it helps if it's too deeply nested. I like Julia's |>, which (in my opinion) makes code a lot more readable.
Jelly, 30 bytes
69266249554160949116534784œSÆl
This can't be tested online since TIO has a 60 second timeout.
Verification
$ time jelly eun '69266249554160949116534784œSÆl'
69266249554160949116534784
real 1m0.033s
user 0m0.433s
sys 0m0.041s
How it works
The natural logarithm (Æ...
let stacks = [ ]; // Data items
let loops = [];
let index = 0;
let next = 0;
let prog = "--<-<<+[+[<+>--->->->-<<<]>]<<--.<++++++.<<-..<<.<+.>>.>>.<<<.+++.>>.>>-.<<<+.".chars;
let output = "";
for (let char in prog) {
if (char == '>') {
index += 1;
} else if (char == '<') {
index -= 1;
} else if (char == '+') {
stacks[index] = ( stacks[index] is what is nil ? 1 : stacks[index] + 1 );
} else if (char == '-') {
stacks[index] = ( stacks[index] is what is nil ? -1 : stacks[index] - 1 );
My Downgoat avatar has several distinct features
These features can however also apply to any other animal.
Specification
Given an image of an animal (technically can be anything), you must apply the Downgoat properties to it.
Border pixels are the outer most pixels of the image.
The back...
The bug that I mentioned, # ImageMagick 7.0.1 through 7.0.3-7 fails here has been reported to the IM developers and is fixed in version 7.0.3-8. — Glenn Randers-PehrsonNov 20 at 16:52
Reverse Deltas of an Array
A continuation of Inverse Deltas of an Array
Your task is to take an array of signed 32 bit integers, recompile it with its deltas reversed.
Example
The List,
18 19 17 20 16
has the deltas:
1 -2 3 -4
which, when reversed, yeilds:
-4 3 -2 1
...
Stuck, 0 bytes
Well, can't get shorter than that...
An empty program will output Hello, World! in Stuck.
Mathematica, score 14125.71
"a.png"~Export~ConstantImage[{75,91,110}/256,{386,320}]
Simply saves this image:
to a.png.
Jelly, 30 bytes
69266249554160949116534784œSÆl
This can't be tested online since TIO has a 60 second timeout.
Verification
$ time jelly eun '69266249554160949116534784œSÆl'
69266249554160949116534784
real 1m0.033s
user 0m0.433s
sys 0m0.041s
How it works
The natural logarithm (Æ...
My Downgoat avatar has several distinct features
These features can however also apply to any other animal.
Specification
Given an image of an animal (technically can be anything), you must apply the Downgoat properties to it.
Border pixels are the outer most pixels of the image.
The back...
