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This "sandbox" is a place where Code Golf users can get feedback on prospective challenges they wish to post to main. This is useful because writing a clear and fully specified challenge on your first try can be difficult, and there is a much better chance of your challenge being well received if you post it in the sandbox first.

Sandbox FAQ

Posting

To post to the sandbox, scroll to the bottom of this page and click "Answer This Question". Click "OK" when it asks if you really want to add another answer.

Write your challenge just as you would when actually posting it, though you can optionally add a title at the top. You may also add some notes about specific things you would like to clarify before posting it. Other users will help you improve your challenge by rating and discussing it.

When you think your challenge is ready for the public, go ahead and post it, and replace the post here with a link to the challenge and delete the sandbox post.

Discussion

The purpose of the sandbox is to give and receive feedback on posts. If you want to, feel free to give feedback to any posts you see here. Important things to comment about can include:

  • Parts of the challenge you found unclear
  • Comments addressing specific points mentioned in the proposal
  • Problems that could make the challenge uninteresting or unfit for the site

You don't need any qualifications to review sandbox posts. The target audience of most of these challenges is code golfers like you, so anything you find unclear will probably be unclear to others.

If you think one of your posts requires more feedback, but it's been ignored, you can ask for feedback in The Nineteenth Byte. It's not only allowed, but highly recommended! Be patient and try not to nag people though, you might have to ask multiple times.

It is recommended to leave your posts in the sandbox for at least several days, and until it receives upvotes and any feedback has been addressed.

Other

Search the sandbox / Browse your pending proposals

The sandbox works best if you sort posts by active.

To add an inline tag to a proposal, use shortcut link syntax with a prefix: [tag:king-of-the-hill]. To search for posts with a certain tag, include the name in quotes: "king-of-the-hill".

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4643 Answers 4643

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Brainf*** Polygot

Write a brainf*** interpreter in as many languages as possible.

You will take the brainf*** code on standard input, and then execute it.

Your score is bytes / (n * sqrt n) (where n is the number of languages in which your program works), which you will seek to minimize.

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8
  • \$\begingroup\$ I don't think the generic "preform <simple task> in as many languages as possible" [polyglot] task is gonna cut it anymore. Maybe add some new BF-related task. \$\endgroup\$ Jan 24, 2018 at 5:04
  • \$\begingroup\$ @EsolangingFruit This isn't "preform some simple task". This is "be Turing complete". No other polygot challenge can be used a universal turing machine. In particular, it requires you to use the turing complete facilities of all the languages involved. \$\endgroup\$ Jan 24, 2018 at 5:06
  • \$\begingroup\$ If your goal is "prove turing completeness", then maybe "write a polyglot interpreter for a Turing-complete language". Allow different languages to interpret different TC languages. \$\endgroup\$ Jan 24, 2018 at 5:10
  • \$\begingroup\$ @EsolangingFruit I guess that would make it more interesting. I kind of like the idea of them all doing the same thing though, so you can just "feed in" an algorithm and get an instant polygot. \$\endgroup\$ Jan 24, 2018 at 5:19
  • \$\begingroup\$ @EsolangingFruit What about a caveat that the you must feed in the currently executing language as a parameter (for example, when run with python, it executes the code with "python" as its first input). \$\endgroup\$ Jan 24, 2018 at 5:20
  • \$\begingroup\$ In my opinion, polyglot challenges are better when you're solving different problems in each language. That has the advantage of being more interesting to solve, as well as not needing to ban multiple similar versions of the same language (since making polyglots would be trivial in those). \$\endgroup\$ Jan 24, 2018 at 5:25
  • \$\begingroup\$ Alternatively, a more difficult version: a polyglot in some set of languages languages that acts a compiler from BF to a new polyglot in each of those languages. In that case you probably want to score by no. of languages \$\endgroup\$ Jan 24, 2018 at 5:27
  • \$\begingroup\$ @EsolangingFruit OW, that sounds even cooler! \$\endgroup\$ Jan 24, 2018 at 5:39
-2
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Gatherer Golf: The 61 Dwarves

Gatherer is the official tool for searching for Magic: The Gathering cards. Its advanced mode allows searching by most of the criteria you could hope for, as well as simple boolean combinations within a single kind of criterion (for example, you can do "name contains X or Y and not Z").

I've been using it a lot recently, and have been trying to get better at more quickly finding the exact set of cards I need. For example, if I want creatures that can generate mana, searching for "dd {" seems to be the minimal exact string match on their rules text.

For this inaugural Gatherer Golf, your challenge is to create a query that lists, exactly, the 61 Dwarf cards (not counting creatures that are all creature types), without using the key "subtype". The result generated the normal way can be found here.

Rules

  • Your score is the length of the full URL in Gatherer. For example, searching for "name contains Dw or Resp and type contains Creature" generates the URL gatherer.wizards.com/Pages/Search/Default.aspx?action=advanced&name=|[Dw]|[Resp]&type=+[%22Creature%22] for a score of 104.

    • Lowest score wins.
    • Your URL can be manually generated; it doesn't have to be possible to create it via the advanced search form.
    • Cards added to Gatherer after this challenge was posted (in this case, after Rivals of Ixalan) do not invalidate existing answers. Your answer may include or exclude any card published after that date, regardless of whether it's a dwarf, and answers that no longer give correct results (for example, because the Oracle text of a card changed) do not need to be deleted.
    • Other than as described above, all cards in Gatherer are relevant to this challenge, regardless of whether they're legal for tournament play.
    • Don't DOS Gatherer or otherwise break its terms of service.
    • The cards may be listed in any order. This may be relevant if your search contains more than just dwarves, but concentrates all the dwarves into one page of the search results.
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3
  • 1
    \$\begingroup\$ I'm not sure that this requires code to solve. Also, I'd ban the word "subtype" in the query, as that's more solid than "without querying on subtype" \$\endgroup\$ Jan 31, 2018 at 20:26
  • \$\begingroup\$ Thanks, edited. I was thinking of the query itself as code--it's declarative and certainly doesn't meet our definition of a programming language, but I'd've expected an HTML or SQL golfing challenge to be on-topic here and this seems the same in principle. \$\endgroup\$
    – histocrat
    Jan 31, 2018 at 21:02
  • \$\begingroup\$ I wouldn't expect HTML golfing to be on-topic; and SQL meets the definition of a programming language. IMO the way to make this on-topic is to somehow supply a database (maybe abusing imgur with steganography?) and then ask for a program which takes input as a list of card names to match and outputs a minimal query. \$\endgroup\$ Feb 2, 2018 at 12:28
-2
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xkcd-esque Reverse Code Golf

Introduction

A new xkcd comic came out recently, seemed to be a fun challenge and a change from the usual code golfing.

enter image description here

So I set out on making this challenge!

Challenge

Make a short snippet of code in any language which, when read out, sounds like 1 sentence of normal English literature (for example, Moby Dick in the comic).

Rules

  • The snippet doesn't have to run, so you are free to add statements which would not execute (for example: undeclared variables, functions, etc.). However, it must be syntactically correct.

  • A word in this challenge is any sequence of letters considered as valid English as in a dictionary. Articles (a, an, the) are counted as words.

  • To prevent too long answers, the maximum number of words will be fixed at 200 individual words. This includes operator expansion.

  • The maximum length of any function or variable name will be 10 words.

  • The expansion used for an operator must be specified in the answer.

  • Imported and built-in functions are not considered as operators.

  • Since this is reverse code golf, the answer with the most points wins.

Scoring criteria:

  • Characters used to structure code (0): All kinds of brackets, statement terminators, whitespace, etc.
  • Comments and String literals (0): To avoid making large comments/literals with actual literature
  • Names of functions or variables (1 per character):
  • Keywords (2 per letter): Using keywords in the story as valid syntax.
  • Operators (2 per letter of expansion): For example, > is worth 2x13 (isGreaterThan).

Examples

Valid:

try { throw IngTheBallAnd; } catch (Ing it) {}
// Worth 3x2 + 5x2 + 13 + 5x2 + 3 + 5 = 37 points

let myLife = "a quote";
// Worth 3x2 + 6 + 2x2 = 16 points ("=" used as "be")

Invalid:

// One does not simply write everything in a comment
// Worth 0

Hope this meets PPCG puzzle criteria :D

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16
  • \$\begingroup\$ Define "short" Otherwise answers could just go on and on to approach infinite score. \$\endgroup\$
    – Adám
    Feb 28, 2018 at 10:05
  • \$\begingroup\$ How long may function/variable names be? \$\endgroup\$
    – Adám
    Feb 28, 2018 at 10:07
  • \$\begingroup\$ How do we determine the exact expansion of operators? E.g. is * "times" or "multipliedBy"? \$\endgroup\$
    – Adám
    Feb 28, 2018 at 10:09
  • \$\begingroup\$ So the APL function ×× would count as 28: (signOfTheTimes)? Indeed APL functions often read nicely as plain English. E.g. (?∘≢⊃⊢)¨(⊂⍳3)/⍨¨1+⊢ reads as "a random number up to (?) the length () selects from () the value of () each of (¨) the entire () indices until () three (3) replicated (/) by () each of (¨) one (1) added to (+) the value of the argument (). \$\endgroup\$
    – Adám
    Feb 28, 2018 at 10:26
  • \$\begingroup\$ @Adám I'll edit my answer to answer these. As for APL, I guess my puzzle is no match for it :P \$\endgroup\$ Feb 28, 2018 at 10:46
  • \$\begingroup\$ @Adám I'd actually aim for english literature rather than procedure sentences \$\endgroup\$ Feb 28, 2018 at 10:50
  • \$\begingroup\$ What is a "determiner"? Some programming languages do not use white space. What is a word? \$\endgroup\$
    – Adám
    Feb 28, 2018 at 11:05
  • \$\begingroup\$ "Context" determination of expansion is not an exact science. As long as your challenge has that feature, I predict it will be closed as "unclear what you are asking". \$\endgroup\$
    – Adám
    Feb 28, 2018 at 11:07
  • \$\begingroup\$ Are built-in functions "keywords"? What about imported functions? \$\endgroup\$
    – Adám
    Feb 28, 2018 at 11:08
  • \$\begingroup\$ @Adám Edited to answer. Determiners were meant to be Articles (a, an, the). Lack of whitespace is not a concern as long as it is readable. I mentioned the need for specifying the intended meaning of operators before, but it was a partial change. \$\endgroup\$ Feb 28, 2018 at 12:13
  • \$\begingroup\$ built-in functions are not considered as operators? Uh, what exactly is an operator then? Some languages use single letters as operators. I'm afraid this question makes far too many assumptions about the features of programming languages. A common mistake, but often hard to fix. Compare to the problems with atomic code-golf. \$\endgroup\$
    – Adám
    Feb 28, 2018 at 12:53
  • 5
    \$\begingroup\$ There have been a few questions about reading code as sentences, e.g. 1, 2, 3. Because answers can't be objectively scored, those are popularity-contests. However those types of challenge have mostly fallen out of scope on the site and are very hard to get right, see the tag wiki for more infos. \$\endgroup\$
    – Laikoni
    Feb 28, 2018 at 12:56
  • \$\begingroup\$ Hmm.... alrighty. I shall disband this puzzle. I hope someone can make a better puzzle with the comic, it ought to get its own challenge ;) \$\endgroup\$ Feb 28, 2018 at 13:17
  • 3
    \$\begingroup\$ No one have said that? Welcome to PPCG! \$\endgroup\$ Mar 1, 2018 at 0:05
  • \$\begingroup\$ Note that this is called code-bowling on PPCG. Typically code bowling questions have strict scoring rules to avoid arbitrary score inflation which usually prevents large variable/function names. \$\endgroup\$
    – Jo King Mod
    Mar 1, 2018 at 2:19
-2
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Bees?

Inspired by SCP-3045

Write a program that takes the input, extracts all of the words, and looks for the word bee; then:

  • If bee is not detected, pick sections of the text at random and delete them.
  • If bee is detected, add instances of the word bee to the input such that it has significantly more bytes than the original input.

The program should then output these modifications.

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  • 1
    \$\begingroup\$ How much is significantly more? Why is it popularity-contest? \$\endgroup\$
    – Laikoni
    Mar 18, 2018 at 14:00
  • 1
    \$\begingroup\$ Do X creatively pop cons have fallen out of scope. This will get closed instantly if posted on main. \$\endgroup\$
    – Dennis
    Mar 19, 2018 at 12:51
-2
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Move a window around the screen

Your code should open a new window that is at least 100 by 100 pixels in size. Once the window is open you should be able to move the window around the screen using the keyboard. The window should move smoothly but it doesn't matter how fast it moves.

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3
  • 2
    \$\begingroup\$ Is there anything else that could make this challenge a bit more interesting? Maybe a scoring method? \$\endgroup\$
    – RamenChef
    Mar 26, 2018 at 14:01
  • \$\begingroup\$ @RamenChef I suppose the scoring method was meant to be by the code-golf rules. I could make the challenge more interesting maybe by insisting that you can type into the window? \$\endgroup\$
    – user9206
    Mar 26, 2018 at 14:05
  • 1
    \$\begingroup\$ What counts as a "window"? I think this might be quite hard to define objectively in a way which is OS-agnostic. \$\endgroup\$ Mar 26, 2018 at 15:38
-2
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Output a Random Bit

Your task is simple: print either 1 or 0.

Chosen uniformly randomly every time.

No, not your silly pseudorandom nonsense. No system calls. No reading /dev/urandom. The randomness has to be unpredictable (i.e. reliant on chaotic, impossible-to-reasonably-model natural phenomena, and not on some configuration of bits in your computer).

Specifications

  • It is OK to query a site such as random.org for your bit.
  • Your program only needs to be runnable once per day (i.e. you can assume there is a 24 hour gap between executions). This is to work around the fact that sites like random.org often have rate-limits.
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  • \$\begingroup\$ If it only has to be run once a day, wouldn't millis() % 2 be truly random? \$\endgroup\$
    – geokavel
    Apr 2, 2018 at 3:22
  • 1
    \$\begingroup\$ @geokavel No, because you can't assume that the calling actions will be random (e.g. I could always invoke the program at 25-hour intervals, meaning that millis() % 2 would always be a consistent value. \$\endgroup\$ Apr 2, 2018 at 4:11
  • \$\begingroup\$ Is a time cost of maybe read a file in nanoseconds allowed? \$\endgroup\$
    – l4m2
    Apr 2, 2018 at 4:42
  • 1
    \$\begingroup\$ In its current form, it appears to be impossible to define the validity criteria objectively. Temporary -1. \$\endgroup\$
    – DELETE_ME
    Apr 2, 2018 at 6:39
  • \$\begingroup\$ @user202729 If it were up to you, how would you define them? \$\endgroup\$ Apr 2, 2018 at 6:45
  • \$\begingroup\$ /dev/random seems to be really random. Is it allowed? \$\endgroup\$ Apr 2, 2018 at 7:30
  • \$\begingroup\$ @someone Wikipedia says it's a PRNG, and I've heard that system randomness tends to draw entropy from sources like startup times and user actions, so that wouldn't count. \$\endgroup\$ Apr 2, 2018 at 7:42
  • \$\begingroup\$ Would a HRNG such as RdRand work? \$\endgroup\$ Apr 2, 2018 at 8:24
  • \$\begingroup\$ ... I admit that my downvote/comment is not constructive, but I found absolutely no way to objectively define the challenge. \$\endgroup\$
    – DELETE_ME
    Apr 2, 2018 at 14:02
  • \$\begingroup\$ Maybe define "real random" as "not only based on xxx"(currently last state, calling current) \$\endgroup\$
    – l4m2
    Apr 2, 2018 at 15:38
  • \$\begingroup\$ @l4m2 That was what I was trying to imply by saying it shouldn't be pseudorandom. \$\endgroup\$ Apr 2, 2018 at 18:47
  • \$\begingroup\$ @EsolangingFruit but you need to define what's pseudo \$\endgroup\$
    – l4m2
    Apr 2, 2018 at 18:52
-2
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Let's play the too high too - low game!

TL:DR : write a code that plays the too high - too low game


Given this pseudo code function for the too high - too low game, write it in your language of choice. This is just to make the challenge work better across all languages. This code won't count in the final score. You may also change the function's name and any of its variable's name too.

function isRight(number, guess):  # where the number is the correct answer and the guess is your code's guess

    if guess < number:            # if the guess is too low
        return 0                  # return 0

    else if guess > number:       # if the guess is too high
        return 2                  # return 2

    else if guess == number:      # if the guess is right
        return 1                  # return 1

    else:                         # if there is an error
        return -1                 # return -1

The challenge

Write a code, function, script, etc. that guesses the right number. The range of the "random" number will be between 0 inclusively and 100 exclusively. For the sake of this challenge, the "random" numbers will be the test cases. Note that hard-coding the test cases is banned.


Scoring

This is how the score will be counted:

bytes = number of bytes in your code
tries = the sum of all the tries used to guess all the test cases

score = bytes + tries

Rules

  • Hard-coding the test cases if forbidden.

Test cases

[0,2,4,13,19,21,26,33,38,42,48,50,51,56,66,69,74,75,80,89,98,99]
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3
  • \$\begingroup\$ For one, i'd say the randomness is unfair. If you manipulate the seed python is given, you can just have it output a known sequence. Alongside that, can't you just hardcode the testcase? EDIT: Hardcoding the test case is the only way to get a good score. \$\endgroup\$ Mar 29, 2018 at 16:38
  • \$\begingroup\$ @moonheart08 would banning hardcoding the test cases help? \$\endgroup\$
    – Dat
    Mar 29, 2018 at 17:57
  • 1
    \$\begingroup\$ "the sum of all the tries used to guess all the test cases" Won't this be the same for all answers (with the only difference being floor vs ceil when taking halve the previous guess (as in 75 & higher could result in a next guess of either 87 or 88).First guess will always be 50. Is it lower, guess 25; is it higher, guess 75. etc. etc. Btw, there are already a few Guess the number challenges: Here is one; and here is another one. \$\endgroup\$ Apr 3, 2018 at 12:54
-2
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I see a window and I want it painted black

Yes, I know this is a popular mishearing of the lyrics. But instead of a red door, I really do want an (application) window painted black.

Your standalone program should launch an application window at least 400x400 and fill it entirely with black. It doesn't need to be borderless, and it doesn't need to exit gracefully.

Running in a browser is insufficient because there are still elements of the window such as the address-bar and tab-bar that aren't painted black. You must paint the whole window black except for borders added by your window manager.

This is code golf. Standard loopholes apply. Additional challenge is to listen to The Rolling Stones while making your submission.

Here is an un-golfed Java solution:

#compile: javac BlackWindow.java
#run: java BlackWindow
import java.awt.Color;
import java.awt.Frame;

public class BlackWindow{
  public static void main(String[] args){
    Frame frame = new Frame("no colors anymore");
    frame.setsize(400, 400);
    frame.setLocationRelativeTo(null);
    frame.setBackground(Color.Black);
    frame.setvisible(true);
  }
}
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6
  • \$\begingroup\$ What if my platform doesn't support windows that large? \$\endgroup\$
    – Nissa
    Apr 20, 2018 at 23:17
  • \$\begingroup\$ What is the 400x400 measured in? Pixels? Does it qualify if I somehow emulate a screen with larger resolution? \$\endgroup\$
    – DELETE_ME
    Apr 21, 2018 at 9:23
  • \$\begingroup\$ Does making the whole screen black count? \$\endgroup\$
    – DELETE_ME
    Apr 21, 2018 at 9:24
  • \$\begingroup\$ Stephen then make the whole screen black? What kind of system doesn't support that? \$\endgroup\$
    – Jared K
    Apr 22, 2018 at 0:16
  • \$\begingroup\$ user202729 i was thinking pixels \$\endgroup\$
    – Jared K
    Apr 22, 2018 at 0:16
  • \$\begingroup\$ What if I am listening to The Feelies cover of the song? Do I get the bonus point? +1 from me for an unusual challenge. \$\endgroup\$
    – JayCe
    Jun 11, 2018 at 3:34
-2
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Shorter coding in non-golfing language

Copper write a requirement, a sample program in a golfing language, and a required non-golfing language. Rob hack it with the required language, with fewer bytes of code.

I guess it'd be cuz it's sometimes hard to define which is "golfing language". Also is it a duplicate?

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3
  • \$\begingroup\$ If it's a cops-and-robbers, then it can't be a popularity-contest. I personally don't think this challenge would work out; first of all, it's virtually impossible to outgolf a golfing language using a non-golfing languages because most golfing languages can complete most reasonable tasks in fewer bytes than it takes a non-golfing language to even print Hello World. Also like you said, golfing/non-golfing is extremely difficult to define. I also don't think this challenge would be particularly interesting because you'd likely end up with a bunch of miscellaneous cops posts with all \$\endgroup\$
    – hyper-neutrino Mod
    May 2, 2018 at 13:09
  • \$\begingroup\$ sorts of random requirements, which is basically just going to be a bunch of questions that either exist on PPCG already or could be posted to PPCG main as its own challenge, without any robber posts because it would be basically impossible. \$\endgroup\$
    – hyper-neutrino Mod
    May 2, 2018 at 13:09
  • 3
    \$\begingroup\$ IMO this is well past the threshold of "Too Broad", so I would vote to close for that reason. \$\endgroup\$ May 2, 2018 at 15:23
-2
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(Now I don't know what the name should be)

Intention

I want to create a challenge based on dependent typing, feature that exists in Idris, Coq, Agda and the similiar.

Text

You should create a function in dependently typed language (Idris, Coq, Agda, etc) so that:

  1. The function will receive a string that denotes format.
  2. The format string will have s or n, s means it will receive a string, n means it will receive a number. You can assume that there is no other thing in the string
  3. Arguments is received in order. If there is type mismatch, the error must be reported on compile-time.
  4. After all arguments is received, the function will return a string, that is list of all passed argument

For example

formatf "sn" "goods" 25
> "goods 25"
formatf "sn" "goods" "bad"
> Type error in compile time
formatf "ak" "Akangka" 25
> You can do anything.
formatf "nnn" 24 25
> Either type error or return a function expecting a number and return string (currying is almost universal in these languages)
formatf "ss" "Akangka" "Martin Ender" "Adám"
> Type error on compile time

This challenge is similiar to printf-style string formatting, the difference that the function in this challenge has to be type safe.

Note that you cannot use build-in function or macro to do this

Discussion

  1. What should be the name of this challenge?
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15
  • \$\begingroup\$ Any reason why full programs are not allowed? \$\endgroup\$
    – DELETE_ME
    May 2, 2018 at 9:29
  • \$\begingroup\$ What happens if the language is not compiled? \$\endgroup\$
    – DELETE_ME
    May 2, 2018 at 9:32
  • 1
    \$\begingroup\$ (if you didn't realize, it's not just some languages can't solve it, but in some languages your requirements don't make any sense. There are languages without functions, language with only monadic functions, languages without integers, language without macros, language where macros have different meaning than C #define, language without string (C), etc.) \$\endgroup\$
    – DELETE_ME
    May 2, 2018 at 9:59
  • \$\begingroup\$ If the string is possibly not known at compile time, how can it produce a type error at compile time? \$\endgroup\$
    – Angs
    May 2, 2018 at 10:04
  • \$\begingroup\$ Personally I think it's a bit too similar to the challenge you linked.. The only difference is validating the input-type with the format.. In which case it would be better to have a challenge dedicated to that, as in: Given this format and a variable amount of other objects, check if the format and types of these objects match. In which case "%s: %i%%", "Percentage", 25 would be truthy, and "%s: %i%%", 123.45, 25 would be falsey. In addition, most languages are type independent, which can change during run-time based on their use.. 10.0 could be all three types in some languages.. \$\endgroup\$ May 2, 2018 at 10:07
  • \$\begingroup\$ Suggested re-working of the problem: Given a pattern using only %s and %n (for number), slot in the given list of strings and numbers in the given order, but return a distinct value or throw an error if the given list doesn't fit right. \$\endgroup\$
    – Adám
    May 2, 2018 at 10:08
  • \$\begingroup\$ @Angs dependent typing. In fact, this challenge is about dependent typing. \$\endgroup\$
    – Xwtek
    May 2, 2018 at 10:17
  • \$\begingroup\$ @user202729 well, by compile-time, I mean about typechecking time. I specifically disallow dynamic typing, as one of the point of the challenge is to make the program fail to typecheck if %s format is supplied by integer, etc. \$\endgroup\$
    – Xwtek
    May 2, 2018 at 10:21
  • \$\begingroup\$ @KevinCruijssen Indeed, not all language can do this challenge. After all the intention is on the dependent typing, which most programming language (but not Idris, Coq, etc) lack. \$\endgroup\$
    – Xwtek
    May 2, 2018 at 10:26
  • \$\begingroup\$ @Adám nice suggestion. But the type-safe feature (i.e. all error is on type-checking time) is integral part of the challenge \$\endgroup\$
    – Xwtek
    May 2, 2018 at 10:28
  • \$\begingroup\$ @Akangka I don't understand why my suggestion doesn't satisfy that. You get a list of strings and numbers and need to check against each tag in the format that you've been given the right tag. \$\endgroup\$
    – Adám
    May 2, 2018 at 12:12
  • \$\begingroup\$ I think you should limit to some languages (perhaps extend the language list if needed), as the challenge does not make sense in other languages anyway. \$\endgroup\$
    – DELETE_ME
    May 3, 2018 at 1:26
  • \$\begingroup\$ @Adám I actually implement your suggestion, except the throw an error part. I make the challenge require the result is type error \$\endgroup\$
    – Xwtek
    May 3, 2018 at 2:03
  • \$\begingroup\$ @Akangka I don't understand why you insist on language specific features like "type errors" and "compile time". Your examples do not show how to format ss, ns, and nn. You mention float dots, but floats are not part of the examples any more. \$\endgroup\$
    – Adám
    May 3, 2018 at 5:46
  • \$\begingroup\$ @Adám thanks about float dots. About language specific features, I just want to create a challenge about dependent typing. \$\endgroup\$
    – Xwtek
    May 3, 2018 at 6:50
-2
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The challenge

  • Write a Discord bot with a single command, !oldest, that gives the oldest user in the server that the command that was run in.

  • Gracefully failing in DM channels is not required.

  • Assume the bot's token is this invalid token: MjM4NDk0NzU2NTIxMzc3Nzky.CunGFQ.wUILz7z6HoJzVeq6pyHPmVgQgV4.
    If the token is compressed in the program, provide instructions on how to change it so I can test it.

Sample discord.py implementation

import discord
client = discord.Client()
@client.event
async def on_message(M):
 if(M.content=="!oldest"):
  N=sorted([x.id for x in M.server.members])[1]
  await client.send_message(M.channel, str(M.server.get_member(N)))
client.run("MjM4NDk0NzU2NTIxMzc3Nzky.CunGFQ.wUILz7z6HoJzVeq6pyHPmVgQgV4")
  1. Get a list of every user in the server
  2. Sort their snowflake IDs
  3. Print the username and discriminator of the member with the smallest ID.

No API for your language? Have fun.

Standard loopholes forbidden, etc, etc.

Shortest code in bytes wins.


Sandbox

I originally posted this question on the main site, but I deleted it, as it turns out I'm bad at writing these. Please forgive me.

\$\endgroup\$
4
  • 1
    \$\begingroup\$ I'm sure I've seen this already, but with comments saying that it needed a lot more information to be self-contained. It still needs a lot more information to be self-contained. \$\endgroup\$ May 5, 2018 at 11:11
  • \$\begingroup\$ Yep. I've edited the question to clarify. \$\endgroup\$ May 5, 2018 at 12:35
  • 2
    \$\begingroup\$ Are you talking about discord servers? Other than form the example this is not clear at all. What is a DM channel? What is a token in this context? \$\endgroup\$
    – flawr
    May 5, 2018 at 13:02
  • \$\begingroup\$ A: Clarify that you're talking about Discord B: When you make a challenge that requires a library does that mean I can use a library that conveniently has the command you're asking of? \$\endgroup\$
    – IQuick 143
    May 6, 2018 at 2:12
-2
\$\begingroup\$

Quecho, a quine-like implementation of echo.

Challenge:

Your challenge is to write a quine-like program that takes a string from stdin and gives two outputs: Output A is the input string. Output B is your source code.

Output Formats:

You can send your outputs to stdout, stderr, and/or files. If A and B go to the same output, they must be separated by a newline. Having a newline at the beginning of your source doesn't count. You'd need to print that newline from your source and then another newline to separate A and B.

Examples:

source: print($stdin+"\n"+codeThatGeneratesSource)

input: Hello, World!

Both outputs on stdout:

Hello, World!
print($stdin+"\n"+codeThatGeneratesSource)

Separate Outputs:

stdout: Hello, World!

stderr: print($stdin+"\n"+codeThatGeneratesSource)

Standard loopholes are forbidden.

Submissions should be proper quines except that they produce the additional specified output.

\$\endgroup\$
3
  • \$\begingroup\$ Related: codegolf.stackexchange.com/questions/66276/quat-quine-cat \$\endgroup\$
    – Beefster
    Jun 1, 2018 at 16:27
  • \$\begingroup\$ Good find. Not a dupe because that calls for either printing the source or printing the input, not both. Also it requires testing length of input, where this does not. \$\endgroup\$
    – Jared K
    Jun 1, 2018 at 16:38
  • 2
    \$\begingroup\$ How is this any different from that, though? The concept of printing the source and printing the output is the same, and I can't see how only a small tweak wouldn't be able to port an answer between the challenges. \$\endgroup\$
    – LyricLy
    Jun 3, 2018 at 5:32
-2
\$\begingroup\$
  • This is in sandbox to check whether or not to repost the BrainF**k interpreter challenge. The links have been given in credits.
  • Should comment handling be required.
  • Also any other improvements are welcome

BrainF**k:

BrainF**k is an esoteric programming language designed in the 90s. The reason for its fame is that understanding a program longer than 10 characters in the language is quite hard.

Example program :

>++++++++[<++++++++>-]<++++++++++++++++.[-]

Guess what this does.


Commands:

Brainf**k operates on an array of memory cells, also referred to as the tape, each initially set to zero. There is a pointer, initially pointing to the first memory cell.

There are a total of eight commands in BF and these are as follows:

Command       |                              Purpose
  >           |      increment the data pointer (to point to the next cell to the right).
  <           |      decrement the data pointer (to point to the next cell to the left).
  +           |      increment (increase by one) the byte at the data pointer. 
  -           |      decrement (decrease by one) the byte at the data pointer.
  .           |      output the byte at the data pointer
  ,           |      one byte of input, storing its value in the byte at the data pointer.
  [           |      if the byte at the data pointer is zero, then instead of moving the instruction pointer forward to the next command, jump it forward to the command after the matching ] command.
  ]           |      if the byte at the data pointer is nonzero, then instead of moving the instruction pointer forward to the next command, jump it back to the command after the matching [ command.

Note :

+ and - operators increment and decrement the bytes at the at the data pointer, note that if the value reaches 255 then upon a + it would become 0.

255 + 1 = 0

Similarly if the value reaches 0 then upon the next - it would become 255.

0 - 1 = 255

Input:

You will be given two strings as input:

  • The actual BrainF**k code that you are supposed to interpret.
  • the program input (that will eventually be emptied) to be interpreted as an array of bytes using each character's ASCII code and will be consumed by the , instruction

Example:

Program : +[,>,]<.
stdin   : 11111 

Output:

  • the output of the interpreted code, if any was produced by the . instruction.

Example:

For the above mentioned program, the output should be:

output: 1

Notes:

  • Both program and stdin will be given as strings.
  • The output should be a string showing the result after operations.
  • Given input will always be valid, with a valid BrainF**k program.
  • In order to avoid confusion, note that you do not need to output the word output as well

e.g :

 output : 1

in this your output should only be 1. (asked by @Picard)

Credits:

The question was (more or less) already asked here. This has been reposted since that was 7 years old and was outdated as well.

Meta posts on that:


Examples:

Program: +[>>>>+++++[-<++>]<[-<++++++++++>]<[-<<->>]<<-[>-<[-]]>+<,]>[>>+>+<<<-]>>>[<<<+>>>-]<<+>[<->[>++++++++++<[->-[>+>>]>[+[-<+>]>+>>]<<<<<]>[-]++++++++[<++++++>-]>[<<+>>-]>[<<+>>-]<<]>]<[->>++++++++[<++++++>-]]<[.[-]<]<
stdin: Hello, World. This is a program for checking eeeeeeee. Well I have plenty of e
output: 14

Program: ++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.
stdin: 
output: Hello, World

Winning-criteria:

This is , so the shortest code in bytes for each language wins.

\$\endgroup\$
14
  • \$\begingroup\$ @AdmBorkBork : So i should put nothing ? \$\endgroup\$ Jun 1, 2018 at 14:59
  • \$\begingroup\$ @AdmBorkBork : Thanks, done. \$\endgroup\$ Jun 1, 2018 at 15:01
  • \$\begingroup\$ I think some of your notes are too ambiguous to be useful. In particular, "You can have numbers as output where numbers are expected" and "The input will be what it should be" seem to just be... "You are allowed to output numbers if you're allowed to output numbers" and "You can assume that the input is the input" \$\endgroup\$ Jun 1, 2018 at 15:07
  • \$\begingroup\$ Also, it would be good to clarify whether the BF commands are the only characters that will be in the program string, or if we are required to handle other characters as comments. \$\endgroup\$ Jun 1, 2018 at 15:09
  • \$\begingroup\$ @KamilDrakari : Changed. Hopefully better \$\endgroup\$ Jun 1, 2018 at 15:09
  • \$\begingroup\$ @KamilDrakari : I think I will put that as something I would like to know (reasons why this is sandboxed)\ \$\endgroup\$ Jun 1, 2018 at 15:09
  • \$\begingroup\$ I don't believe comment handling would be interesting, so I would rather leave it as "you may assume the program input contains no characters other than ><+-.,[]" \$\endgroup\$ Jun 1, 2018 at 15:32
  • \$\begingroup\$ @KamilDrakari : Okay \$\endgroup\$ Jun 1, 2018 at 15:34
  • \$\begingroup\$ What happens if you move left of the starting position on the tape? Is it undefined behaviour or does it have to work? \$\endgroup\$
    – wastl
    Jun 1, 2018 at 18:58
  • \$\begingroup\$ @wastl : undefined behaviour is ok. \$\endgroup\$ Jun 1, 2018 at 19:00
  • 1
    \$\begingroup\$ 3 things: 1, you need to explain how the memory tape works. You hvaen't really explained that. 2, you should clarify that the output doesn't need to say literally output: 1, you should really allow just 1. 3, don't really bother with comments, it's basically just ignoring other characters. \$\endgroup\$
    – Riker
    Jun 1, 2018 at 22:37
  • \$\begingroup\$ 1. Hopefully done, 2. done, 3. Ok, 2 votes for not having comments. \$\endgroup\$ Jun 2, 2018 at 9:26
  • \$\begingroup\$ What if our language has only one input stream? Can we also accept input as the program and input separated by a ! (or some other character)? \$\endgroup\$
    – Jo King Mod
    Jun 4, 2018 at 2:11
  • \$\begingroup\$ @JoKing : yes, you can \$\endgroup\$ Jun 4, 2018 at 7:42
-2
\$\begingroup\$

Longest reference

Write two code A and B, where len(A)<=1024, running A returns B and running B returns A. Longest B win.

Proper quine rule and no rubbish rule(for code-bowling) apply.

Un-used Code

All code must be used. Meaning the program must fail to always properly complete the task if any individual character (or varying set(s) of characters) is/are removed. Naturally, a subset of the program should not be able complete the task on its own without the rest of the program.

Sandbox notes

  • The "1024" may change
\$\endgroup\$
8
  • 1
    \$\begingroup\$ Actually we have no standard rule for code-bowling to prevent unused code. \$\endgroup\$
    – DELETE_ME
    Jul 5, 2018 at 9:52
  • \$\begingroup\$ (although for this particular challenge, it's not possible to make program arbitrarily long) \$\endgroup\$
    – DELETE_ME
    Jul 5, 2018 at 9:53
  • 3
    \$\begingroup\$ It's pretty easy to abuse this one. Program A prints program C n times, where program C prints program A and then comments out any further copies of C. Make n as large as you can and it's easy. Good code-bowling challenges usually have more restrictions \$\endgroup\$
    – Jo King Mod
    Jul 5, 2018 at 10:34
  • \$\begingroup\$ @JoKing Your solution seems to break the "no rubbish rule" \$\endgroup\$
    – l4m2
    Jul 6, 2018 at 1:10
  • 1
    \$\begingroup\$ As user202729 says, there is no standard "rubbish rule". And if there was, there would be many ways of getting around it. \$\endgroup\$
    – Jo King Mod
    Jul 6, 2018 at 1:25
  • 1
    \$\begingroup\$ Suggestion: Why not have the challenge be to minimise the length of A while maximising the length of B? I'm not sure what the scoring system would be though... \$\endgroup\$
    – Jo King Mod
    Jul 7, 2018 at 3:25
  • 2
    \$\begingroup\$ @JoKing I really like that idea but I don't think it would solve the problem. The issue is that B can still contain "rubbish", so it becomes a kind of busy-beaver problem for A to print the largest amount of nonfunctional code in B. \$\endgroup\$
    – N. Virgo
    Jul 7, 2018 at 4:28
  • 3
    \$\begingroup\$ The "unused code" test is unlikely to be practical for programs longer than about 100 characters. \$\endgroup\$ Jul 7, 2018 at 12:04
-2
\$\begingroup\$

Sort on an infinite-dimension cube

Given a unit cube in the \$n\$-dimensional space. Assume that the vertices of the cube has coordinate \$(x_0, x_1, x_2, \dots, x_n)\$ where \$x_i \in \{0,1\} \forall i\in \mathbb N, 0\le i<n\$.

It's possible to number all vertices with non-negative integers less than \$2^n\$. In this challenge, the vertex with coordinate \$(x_0, x_1, x_2, \dots, x_n)\$ will be assigned with number \$2^0\times x_0+2^1\times x_1+\dots+2^n\times x_n\$.

Each vertex can hold an integer.

In this challenge, you can assume \$n\$ contains a very large (practically infinite) value.


Given \$4096\$ items placing in vertex 0 - vertex 4095, you're to sort them. Other vertices contain undefined values, and may be modified by the program.

However, the program cannot directly access the values held by the vertices. You can only control a memory pointer M, which always lie at a vertex of the cube (call this vertex V). Initially M is at the coordinate \$(0,0,0,\dots)\$. This memory pointer can store exactly 1 integer value.

The following operations on the memory pointer M are alllowed:

  • Store the value held by V into memory of M.
  • Write the value stored by M into V.
  • Compare value stored by M and value held by V. This operation should report to the program 3 different values based on whether the comparison is \$<\$, \$=\$ or \$>\$.
  • Move along an edge (in the direction specified by the program) of the cube. This corresponds to changing exactly 1 coordinate of M from 0 to 1, or vice versa.

Your score is the distance traveled by the memory pointer.


A psuedo-code sample interaction library may be:

obj[Infinity] = {[4096 values]}
ptr = 0, cry = undefined
function move(i): ptr = ptr xor (1 shl i)
function carry(): cry = obj[ptr]
function place(): obj[ptr] = cry
function compare(): return sgn(obj[ptr] - cry)

You can write functions, use IO, or anyway to interact. Lowest move callings win.

\$\endgroup\$
7
  • \$\begingroup\$ Actually I think there are just 12 dimensions. \$\endgroup\$
    – DELETE_ME
    Jul 12, 2018 at 14:55
  • \$\begingroup\$ @user202729 More dimensions exist and you can use them, but they are initally empty \$\endgroup\$
    – l4m2
    Jul 12, 2018 at 14:59
  • 5
    \$\begingroup\$ What does it mean to sort an infinite-dimension cube? Currently this very unclear. \$\endgroup\$
    – Laikoni
    Jul 13, 2018 at 12:46
  • \$\begingroup\$ @Laikoni I'd say code shows enough to understand, so it's not ready to post but not unclear \$\endgroup\$
    – l4m2
    Jul 13, 2018 at 14:25
  • 2
    \$\begingroup\$ No, sorry, it's not so clear to the rest of us. I have no idea what the input is, what the output is, even what obj we're working with and how it relates to an "infinite dimension cube". Many of your questions here (including this one) seem to contain something interesting in them, but they'd be much better received if you post them on the chat room first and explained what you had in mind, and got some help with the question text, at least to the level that they can be meaningfully discussed on. That way your challenges will reach more people too. \$\endgroup\$
    – Sundar R
    Jul 15, 2018 at 10:41
  • 5
    \$\begingroup\$ @sundar I think the sandbox is exactly the place for improving challenges. I'm not sure if using the chat room is necessary. \$\endgroup\$
    – DELETE_ME
    Jul 19, 2018 at 14:35
  • \$\begingroup\$ @Laikoni Better now? \$\endgroup\$
    – DELETE_ME
    Jul 19, 2018 at 15:10
-2
\$\begingroup\$

Golf a regex that matches syntactically valid programs in the language of your choice.

1: Pick a programming language, P, that meets these requirements:

  • P is known to be Turing-Complete.
  • P has a freely available and working compiler or interpreter.

2: Create a regular expression, R, such that:

  • R matches any string that is a syntactically valid program of P.
  • R rejects any string that is a syntactically invalid program of P

3: Golf R. Shortest regex wins.

\$\endgroup\$
6
  • 1
    \$\begingroup\$ For a lot of Esolangs it would just be .*, I think you'd need to restrict the languages to something that doesn't allow any string ALPHABET* or ALPHABET+. Also you'd need to specify a regex flavour. \$\endgroup\$ Jul 27, 2018 at 20:49
  • \$\begingroup\$ Warning: Most low-level languages are not known to be TC. For example C (which is only recently proved TC, AFAIK. Ref) \$\endgroup\$
    – DELETE_ME
    Jul 28, 2018 at 9:21
  • \$\begingroup\$ Hm. int main(){int x=__builtin_popcount(1);} is not syntactically valid C (undefined identifier), but it compiles in GCC. Also, most compilers don't allow too long identifiers. What do you think? \$\endgroup\$
    – DELETE_ME
    Jul 28, 2018 at 9:23
  • 3
    \$\begingroup\$ @user202729: I doubt that you'll find a regex for C (or pretty much any non-esoteric, high-level language) anyways since most of the time you need to check if () are balanced. \$\endgroup\$ Jul 28, 2018 at 15:21
  • \$\begingroup\$ @OMᗺ Just saying...... // For the first comment, typically the answerer just specify the regex flavor in the answer. \$\endgroup\$
    – DELETE_ME
    Jul 28, 2018 at 15:23
  • \$\begingroup\$ Because only those high-level languages have a proper definition of what is a syntax error. The low-level languages are often just "what the interpreter complains about", and there are still different forms of error -- assertion error, runtime, return 1, .... \$\endgroup\$
    – DELETE_ME
    Aug 1, 2018 at 2:49
-2
\$\begingroup\$

Largest and Smallest Numbers Printable

Related: Largest Number Printable

Your goal is to write code that produces a large number. However, when your code is reversed, you must output a small number.

Rules

  • No constants over 10 (like the other challenge)
  • No numeric literals
  • No infinite numbers
  • Each program can only output one number
  • You must have at least two bytes in your program.
  • Your small number must be less than your large number.

Scoring:

Your score is: \$\frac{code~length}{N_{large} - N_{small}}\$. Smallest score wins.

\$\endgroup\$
4
  • \$\begingroup\$ Ban numeric literals. having the code of n 9's and n 0's in a golving language with auto output results in having a score of \$\frac{2n}{(10^n-1)^2}\$ which will go to 0 for arbitrary large n \$\endgroup\$
    – Kroppeb
    Aug 25, 2018 at 11:26
  • \$\begingroup\$ Even with "no constant over 10" the strategy above will still works in languages such as cat. \$\endgroup\$
    – DELETE_ME
    Aug 25, 2018 at 14:16
  • \$\begingroup\$ @kroppeb that's interesting, thanks. \$\endgroup\$ Aug 25, 2018 at 14:49
  • \$\begingroup\$ Like the other challenge I'd suggest a maximum code length and putting a higher penalty on code length. Also, are we allowed to print negative numbers? \$\endgroup\$
    – Jo King Mod
    Aug 28, 2018 at 6:14
-2
\$\begingroup\$

The Tiniest Generic Evolutionary AI



Introduction

The smallest program you can make (measured in bytes) that builds evolving AIs that parses unknown text string A into unknown text string B that still evolves.

All languages are options. Internet connectivity is allowed (but not providing any specific links). The AI must have a choice of commands (allowing variables) from a Turing Complete instruction set.


Scoring

Scoring is two fold: N = Number of bytes of program (ignoring size of AIs generated)

T = The average generations (generations of 200 AIs or less) before your program can evolve an AI that can do the 5 test cases.

Score = 1000/(N*T)


Challenge

Rules: Using the fewest bytes possible, create a generic evolutionary AI that will evolve to parse one supplied but previously unknown string into another supplied but previously unknown string.

What qualifies as an evolutionary AI in this context:

Your Code
Takes an input string
Takes a seed AI Instruction Set(s)
Runs AI Instruction Sets
Rates Each AI Instruction Set against others and against test strings
Evolves AI to create a new set of AI Instruction Set(s) through random mutation and breeding of existing AIs.
=================
AI Code
Is not written by you (except for possibly a seed AI), to be created by your program instead.
Uses a set of *available* instructions that are or are inspired by a known Turing complete instruction set (such as RISC)
Should consist of references to the available instructions and values for them.
  1. The code you write does not parse the strings directly. Instead, it writes output that is a collection of instructions, and reads in a collection of instructions and applies these instructions. (Ugly as it may be, eval is allowed).

  2. It reads in multiple optional instruction sets.

  3. It rates those instruction sets based on which gets closest to parsing the input string into the target string.

  4. The best performing instructions sets are encouraged in some way.

  5. The worst performing instruction sets are discouraged and/or eliminated in some way.

  6. Using existing AI-oriented libraries is discouraged.

  7. Allowing evolutionary AIs to use develop using a turing-complete set of instructions is encouraged. (Example solution uses a modified RISC instruction set.)

  8. Instruction sets must be able to mutate (randomly change) between generations. They are allowed to breed (selectively change) between generations as well.

  9. Multiple iterations of comparing and evolving instructions sets is possible.

  10. How quickly your AIs evolve or how well they do the job doesn't matter so much as they can get better at the task over iterations.

  11. A seed starting instruction set is allowed. If your solution requires an inputed file for an initial instruction set, a functional example is required and counts towards the byte count.

  12. It handles if an instruction set it runs fails to complete, or times out if an AI instruction set goes on too long (default to 30 seconds).

  13. Program must accept in one arbitrary string from a source. (Your choice of a generic commonly used source, such as a web form, command line, or file). It outputs each AI instruction set's result in a similar format it took them in. It may also optionally accept a starter AI set of instructions.

  14. The AI code never gets to interact with the test string it's being graded against.

  15. Your program cannot do any string conversions on the input string on its own, only may act as it's instructed to by the AI.

  16. A seed AI is not allowed to have anything more than a start, end, or return call of some kind (it must evolve any processing steps on its own).


Test Cases:

Can the program evolve an AI that approaches being capable of string conversion of an unknown conversion? (It is recommended not to build the AI to these specific test cases, these are for the point of testing genericness. Do not specifically target these cases until reporting results, and others testing your program may test them against other string conversions and rate accordingly.)

Five examples follow -

abcdefghijklmnopqrstuvwxyz

will be converted into

zyxwvutsrqponmlkjihgfedcba

or possibly

1010101100110101011001

will be converted into

0101010011001010100110

or possibly

"Mary had a little lamb."

will be converted into

"Gary had a little ham."

or possibly

"Banana"

will be converted to

"Banananananananananananananananana."

Or maybe

The entire text of the Bible

will be converted to

The entire text of the Bible, but every instance of "sheep" is replaced with "codfish".


Short Diagram of interaction.

   STEP 1                         STEP 2                     STEP 3  ...

 Input String           ->
 Expected Output String ->   Your Code Starts  ->    Assorted AI Instruction sets. ->      ->        ->       ->      Your Code Processes AI Instruction Sets -> Your code compares, mutates, and breeds AIs to create new generation -> Return to Step 3
 Seed AI                ->                     (Example: AI1 -> Start(Input); Output(Input)
                                                         AI2 -> Start(Input); CP(Mem1, Mem2); Output (Mem2);)

Example

An on-a-whim project done that roughly followed these rules and inspired this challenge that ran <1000 lines of code (although short, it did not aim for minimal characters.)

myLittleAI

\$\endgroup\$
11
  • 1
    \$\begingroup\$ There are a lot of restrictions and rules, however there is no clear description of the task itself: What does "parse one string into another string" mean? About the rules: Overriding loop-holes such as allowing internet-connectivity is likely to create problems or allow boring answers. "Answer must evolve using options that are or are inspired by a Turing complete instruction set." seems like it's a non-observable requirement (and you override the rule in the second rule anyways). Why do you want to disallow libraries? \$\endgroup\$ Sep 22, 2018 at 23:01
  • \$\begingroup\$ Some of the other rules don't make sense to me, but it's likely to be caused by me not being able to understand the challenge itself. \$\endgroup\$ Sep 22, 2018 at 23:01
  • \$\begingroup\$ @BMO Reason to disallow libraries is that there are existing libraries that are AI libraries. Allowing them means you just call some monolithic AI library and you're done. I guess it'd make sense to just not allow AI libraries though? \$\endgroup\$
    – lilHar
    Sep 24, 2018 at 15:57
  • \$\begingroup\$ Maybe disallowing AI-libraries could be a sensible idea, but I wouldn't know how to put this (ie. what is an AI-library and what is a regular library) formally. Though the standard (this does not mean that it's always the case or that you need to follow it) is to not disallow such things but rather discourage it. If I'd use a library which is not part of the standard libraries it would count as a different language, eg. Python 3 + scikit and in a perfect world less interesting submissions would be given less upvotes. \$\endgroup\$ Sep 24, 2018 at 17:00
  • \$\begingroup\$ @BMO Rewrote it, does this look better? \$\endgroup\$
    – lilHar
    Sep 24, 2018 at 18:29
  • \$\begingroup\$ I think the rules do look more structured and clean, but I still don't understand the challenge itself. Some questions I think the challenge should answer for which I can't find an answer might help: Are you requiring a program, function or a set of functions? What is the input and output format? What makes a solution valid? What is parsing string A to string B? \$\endgroup\$ Sep 24, 2018 at 22:38
  • \$\begingroup\$ Also, keep in mind that golfed solutions might try to find some kind of weaknesses in your definitions to reduce the problem to the easiest way of solving it which might result in solutions that aren't very interesting from an AI perspective. This challenge might fit better test-battery (you can set a byte-limit motivated by your own code if you want). \$\endgroup\$ Sep 24, 2018 at 22:43
  • \$\begingroup\$ There are 2 critical pieces to this challenge that need to be clear before we can really make this post: 1. What are "Instructions"? 2. When an InstructionSet applies a string, what feedback does the AI get? \$\endgroup\$ Sep 25, 2018 at 16:37
  • 1
    \$\begingroup\$ Finally, realize that rule #10 simply means I can iterate over every possible program until I land on one that works, no AI needed. \$\endgroup\$ Sep 25, 2018 at 16:40
  • \$\begingroup\$ @NathanMerrill Did some clarifying randomness... better? \$\endgroup\$
    – lilHar
    Sep 27, 2018 at 18:49
  • \$\begingroup\$ Not really. Let's chat \$\endgroup\$ Sep 27, 2018 at 19:10
-2
\$\begingroup\$

Rotations Required

Given input 2 values:

\$x >= 0\$ :Distance to travel (float)

\$r>0\$ :Radius of wheel (float)

Output the number of rotations required by the wheel to travel that distance.

Constraints:

Your code must not contain any digits.

You cannot use pi functions (math.pi)

Output must be an integer.(In case exact int is not obtained, floor it) 1.0 is not a valid output, it should be 1.

Test Cases

x       r    o/p
50      1    7
0       34   0
50      0.3  26
44      33   0
5.5     5.5  0
105     5    3
155     5    4
6.28318 1    1 #This signifies that pi was approximated to 3.1419

Scoring:

Score= No. of bytes+20/number of digits taken for pi after decimal point

If you have taken more than 10 digits:

Score= No. of bytes

\$\endgroup\$
12
  • 3
    \$\begingroup\$ "You cannot use pi functions" is an unobservable requirement, which is not allowed. You need some test cases. The no-digits rule won't actually make this problem harder for most golflangs. \$\endgroup\$ Oct 16, 2018 at 12:43
  • \$\begingroup\$ @NathanMerrill The latter is less problematic (and more objective) than the former. \$\endgroup\$
    – DELETE_ME
    Oct 16, 2018 at 14:21
  • \$\begingroup\$ Test cases are not strictly required, but it would make it easier to check if a solution is definitely incorrect. \$\endgroup\$
    – DELETE_ME
    Oct 16, 2018 at 14:22
  • 3
    \$\begingroup\$ Info: Adding constraints just "because the challenge is too easy" usually doesn't make it more interesting (unless the constraints are the main difficulty of the challenge, for example for radiation-hardened challenges) \$\endgroup\$
    – DELETE_ME
    Oct 16, 2018 at 14:24
  • \$\begingroup\$ I will add test cases. @NathanMerrill, there just shouldn't be any inbuilt functions that give pi directly is what I want to say. \$\endgroup\$ Oct 17, 2018 at 5:35
  • \$\begingroup\$ @VedantKandoi I understand what you want, but we allow any language on this site, and it's impossible to define what a "pi-giving function" is to work for all possible languages. \$\endgroup\$ Oct 17, 2018 at 6:26
  • \$\begingroup\$ Is there any other way I could word it then, as I don't want python, java etc. users to use math.pi or should I just remove it? \$\endgroup\$ Oct 17, 2018 at 7:15
  • \$\begingroup\$ Also, since pi is in the formula, exact int will never be obtained, and if anyone uses approximate value of pi, they may get exact int at certain value or 1 less than desired answer. What can I add for this? \$\endgroup\$ Oct 17, 2018 at 7:48
  • \$\begingroup\$ I changed the scoring method for the above issue, so should be okay now. \$\endgroup\$ Oct 17, 2018 at 8:15
  • \$\begingroup\$ Why would the output be floored? Surely you should use ceiling so that the wheel is actually travelling that distance. \$\endgroup\$
    – Jo King Mod
    Oct 17, 2018 at 8:26
  • \$\begingroup\$ I was thinking of something like how many full rotations need to be completed. \$\endgroup\$ Oct 17, 2018 at 8:31
  • 2
    \$\begingroup\$ "Not using a pi function" is a non-observable program requirement, which is one of the things to avoid when writing a challenge. I don't see any way to fix this challenge: fundamentally what it's asking is too trivial to be interesting. My advice would be to delete the body of this answer and then delete the answer (to keep the sandbox tidy) and then to try to come up with a challenge which is inherently interesting enough that it doesn't need that kind of restriction. \$\endgroup\$ Oct 17, 2018 at 14:06
-2
\$\begingroup\$

Write a Self-Hosting Ouroboros: each quine produces the next quine AND its interpreter

My meta-questions, please give feedback and/or add your own:

  • Too elaborate or long post?
  • Rules too strict? Too lax?
  • Not having a deadline: good or bad idea?

A Quine is a program that prints its own source code as output when it is run.

A Self-Hosting Quine (which is something I just made up, although I'm sure it exists already) is a quine that also produces an interpreter/compiler/emulator/whatever for itself (from now on I will just say "interpreter").

I believe this actually means that a lot of essential functionality must be "circularly defined" - for example, to print output, the interpreter must rely on the parent interpreter's ability to print output. So maybe we should call this a Von Munchausen Quine?

An Ouroboros Program or Quine Relay is a quine that prints a different quine, which then prints yet another program, and so on, until the last quine produces the original quine. See this famous example that cycles through over a hundred languages.

A Self-Hosting Ouroboros, then, is quine that produces a program in another language, and also produces an interpreter for that language. The interpreter should be in the current language, so that the next quine can immediately be run and produce the quine after that.

Tangent: obviously, the idea can also be extended to interpreter multiquines but that can be another challenge. Let's make Von Munchausen's Ouroboros first!

Rules

  • The ouroboros must be able to make a complete cycle
  • Score by total quines in chain / shortest source code (in bytes) in the chain (bytes to allow non-textual outputs)
  • Empty quines and interpreters do not count - two character minimum
  • Code-golf languages allowed
  • No languages defined just for this challenge - no "I define language x to always produce quine y in C plus the complete GCC compiler when fed any input"-stuff please
  • Quines must be valid code in their programming languages
  • Interpreters that are partial language implementations are fine, however:
    • it must be able to run the quine, and produce the next quine (obviously).
    • it should be able to run any other correct code that is limited to the same language subset¹. No hyperfitting²!
    • for the sake of code golfing it may accept incorrect code that a normal interpreter should not (the quine is already restricted to correct code anyway)

Clarifications

Yes, you can make a quine that produces itself and its own interpreter

Counts as a 1-chain ouroboros.

What would an "interpreter" for machine code be?

An emulator. Which of course needs some way to load a program and produce the output. You may define a fictional simplified, minimal hardware set-up to do so. For example: a (partial) Z80 emulator where:

  • two hardware ports are connected to send output bytes to (one for interpreter, one for quine). Are those bytes interpreted as raw bytes/ASCI/UTF8 text/whatever? Up to you!
  • the program is already loaded in memory, at whatever address is most convenient (quine too big to fit in the addressable memory space? Define an input port to scan bytes from I guess :P)
  • the PC (program counter), and SP (stack pointer) registers initiate at whatever value is most convenient for creating a quine in Z80 opcode

Obviously, no set-ups with fictional ROM that just happens to contain a new quine, or stuff like that (even though this would be hard to really abuse, since that ROM would still need to be implemented in the emulator).

Am I seriously expecting anyone to create an emulator like this? No, but let's keep the possiblity open (some stack machines might be code golf-friendly enough for the challenge).

"Borrowing" snippets from each other is encouraged, but give accreditation and link to sources!

Because we all really just want to see how long this can get, no? Besides, whatever you take probably has to be heavily modified to fit it in your existing ouroboros chain anyway. Sharing is caring, and accreditation is the decent thing to do.

No dead-line, nor will a winner be selected. Just make as long a chain as possible.


¹ You wrote an interpreter for a subset of Rust, but it doesn't feature the borrow checker? That is fine long as:

  • it works with correct Rust code limited to the language subset
  • it works with the quine itself
  • the quine itself is correct rust code

² Example of what I do and do not consider hyperfitting: if your interpreter can deal with for(var i; i < 10; i++) { a[i] = i; } but crashes without the enclosing {} because it expects them to designate code blocks, that counts as a partial implementation. If var only expects i, or < only expects i and 10? Hyperfitting. If var only accepts single letter names, and < only expects variables on the left and literals on the right? Probably hyperfitting but debatable.

\$\endgroup\$
4
  • \$\begingroup\$ What would the interpreter of a program written in machine code be? \$\endgroup\$
    – DELETE_ME
    Oct 19, 2018 at 15:14
  • \$\begingroup\$ How should we separate the quine output and the interpreter output? \$\endgroup\$
    – Jo King Mod
    Oct 21, 2018 at 0:10
  • \$\begingroup\$ @user202729: an emulator \$\endgroup\$
    – Job
    Oct 21, 2018 at 13:01
  • \$\begingroup\$ @JoKing: hmm, good question. Two separate calls to whatever output method is chosen? (print or its equivalent) \$\endgroup\$
    – Job
    Oct 21, 2018 at 13:03
-2
\$\begingroup\$

Unicode encoder

Do Invent your own Unicode 7.0.0 encoding (as efficient as possible) with score 317754(the lowest possible score). Shortest encode+decode program win.

You can either write two programs doing encode and decode, or write one with argument/input method difference deciding whether it's encoding or decoding

As you may know, the Unicode standard has room for 1,114,111 code points, and each assigned code point represents a glyph (character, emoji, etc.).

Most code points are not yet assigned.

Current Unicode implementations take a lot of space to encode all possible code points (UTF-32 takes 4 bytes per code point, UTF-16: 2 to 4 bytes, UTF-8: 1 to 4 bytes, etc.)


Task
-

Today, your task is to implement your own Unicode implementation, with the following rules:

- Write an encoder and a decoder in any language of your choice
- The encoder's input is a list of code points (as integers) and it outputs a list of bytes (as integers) corresponding to your encoding.
- The decoder does the opposite (bytes => code points)
- Your implementation has to cover all Unicode 7.0.0 assigned code points
- It has to stay backwards-compatible with ASCII, i.e. encode Basic latin characters (U+0000-U+007F) on one byte, with 0 as most significant bit.
- Encode all the other assigned code points in any form and any number of bytes you want, as long as there is no ambiguity (i.e. two code points or group of code points can't have the same encoding and vice versa)
- Your implementation doesn't have to cover UTF-16 surrogates (code points U+D800-U+DFFF) nor private use areas (U+E000-U+F8FF, U+F0000-U+10FFFF)
- Your encoding must be context-independant (i.e. not rely on previously encoded characters) and does NOT require self-synchronization (i.e. each byte doesn't have to infer where it's located in the encoding of a code point, like in UTF-8).

To sum up, here are the blocks that you have to cover, in JSON:

[
  [0x0000,0x007F], // Basic Latin
  [0x0080,0x00FF], // Latin-1 Supplement
  [0x0100,0x017F], // Latin Extended-A
  [0x0180,0x024F], // Latin Extended-B
  [0x0250,0x02AF], // IPA Extensions
  [0x02B0,0x02FF], // Spacing Modifier Letters
  [0x0300,0x036F], // Combining Diacritical Marks
  [0x0370,0x03FF], // Greek and Coptic
  [0x0400,0x04FF], // Cyrillic
  [0x0500,0x052F], // Cyrillic Supplement
  [0x0530,0x058F], // Armenian
  [0x0590,0x05FF], // Hebrew
  [0x0600,0x06FF], // Arabic
  [0x0700,0x074F], // Syriac
  [0x0750,0x077F], // Arabic Supplement
  [0x0780,0x07BF], // Thaana
  [0x07C0,0x07FF], // NKo
  [0x0800,0x083F], // Samaritan
  [0x0840,0x085F], // Mandaic
  [0x08A0,0x08FF], // Arabic Extended-A
  [0x0900,0x097F], // Devanagari
  [0x0980,0x09FF], // Bengali
  [0x0A00,0x0A7F], // Gurmukhi
  [0x0A80,0x0AFF], // Gujarati
  [0x0B00,0x0B7F], // Oriya
  [0x0B80,0x0BFF], // Tamil
  [0x0C00,0x0C7F], // Telugu
  [0x0C80,0x0CFF], // Kannada
  [0x0D00,0x0D7F], // Malayalam
  [0x0D80,0x0DFF], // Sinhala
  [0x0E00,0x0E7F], // Thai
  [0x0E80,0x0EFF], // Lao
  [0x0F00,0x0FFF], // Tibetan
  [0x1000,0x109F], // Myanmar
  [0x10A0,0x10FF], // Georgian
  [0x1100,0x11FF], // Hangul Jamo
  [0x1200,0x137F], // Ethiopic
  [0x1380,0x139F], // Ethiopic Supplement
  [0x13A0,0x13FF], // Cherokee
  [0x1400,0x167F], // Unified Canadian Aboriginal Syllabics
  [0x1680,0x169F], // Ogham
  [0x16A0,0x16FF], // Runic
  [0x1700,0x171F], // Tagalog
  [0x1720,0x173F], // Hanunoo
  [0x1740,0x175F], // Buhid
  [0x1760,0x177F], // Tagbanwa
  [0x1780,0x17FF], // Khmer
  [0x1800,0x18AF], // Mongolian
  [0x18B0,0x18FF], // Unified Canadian Aboriginal Syllabics Extended
  [0x1900,0x194F], // Limbu
  [0x1950,0x197F], // Tai Le
  [0x1980,0x19DF], // New Tai Lue
  [0x19E0,0x19FF], // Khmer Symbols
  [0x1A00,0x1A1F], // Buginese
  [0x1A20,0x1AAF], // Tai Tham
  [0x1AB0,0x1AFF], // Combining Diacritical Marks Extended
  [0x1B00,0x1B7F], // Balinese
  [0x1B80,0x1BBF], // Sundanese
  [0x1BC0,0x1BFF], // Batak
  [0x1C00,0x1C4F], // Lepcha
  [0x1C50,0x1C7F], // Ol Chiki
  [0x1CC0,0x1CCF], // Sundanese Supplement
  [0x1CD0,0x1CFF], // Vedic Extensions
  [0x1D00,0x1D7F], // Phonetic Extensions
  [0x1D80,0x1DBF], // Phonetic Extensions Supplement
  [0x1DC0,0x1DFF], // Combining Diacritical Marks Supplement
  [0x1E00,0x1EFF], // Latin Extended Additional
  [0x1F00,0x1FFF], // Greek Extended
  [0x2000,0x206F], // General Punctuation
  [0x2070,0x209F], // Superscripts and Subscripts
  [0x20A0,0x20CF], // Currency Symbols
  [0x20D0,0x20FF], // Combining Diacritical Marks for Symbols
  [0x2100,0x214F], // Letterlike Symbols
  [0x2150,0x218F], // Number Forms
  [0x2190,0x21FF], // Arrows
  [0x2200,0x22FF], // Mathematical Operators
  [0x2300,0x23FF], // Miscellaneous Technical
  [0x2400,0x243F], // Control Pictures
  [0x2440,0x245F], // Optical Character Recognition
  [0x2460,0x24FF], // Enclosed Alphanumerics
  [0x2500,0x257F], // Box Drawing
  [0x2580,0x259F], // Block Elements
  [0x25A0,0x25FF], // Geometric Shapes
  [0x2600,0x26FF], // Miscellaneous Symbols
  [0x2700,0x27BF], // Dingbats
  [0x27C0,0x27EF], // Miscellaneous Mathematical Symbols-A
  [0x27F0,0x27FF], // Supplemental Arrows-A
  [0x2800,0x28FF], // Braille Patterns
  [0x2900,0x297F], // Supplemental Arrows-B
  [0x2980,0x29FF], // Miscellaneous Mathematical Symbols-B
  [0x2A00,0x2AFF], // Supplemental Mathematical Operators
  [0x2B00,0x2BFF], // Miscellaneous Symbols and Arrows
  [0x2C00,0x2C5F], // Glagolitic
  [0x2C60,0x2C7F], // Latin Extended-C
  [0x2C80,0x2CFF], // Coptic
  [0x2D00,0x2D2F], // Georgian Supplement
  [0x2D30,0x2D7F], // Tifinagh
  [0x2D80,0x2DDF], // Ethiopic Extended
  [0x2DE0,0x2DFF], // Cyrillic Extended-A
  [0x2E00,0x2E7F], // Supplemental Punctuation
  [0x2E80,0x2EFF], // CJK Radicals Supplement
  [0x2F00,0x2FDF], // Kangxi Radicals
  [0x2FF0,0x2FFF], // Ideographic Description Characters
  [0x3000,0x303F], // CJK Symbols and Punctuation
  [0x3040,0x309F], // Hiragana
  [0x30A0,0x30FF], // Katakana
  [0x3100,0x312F], // Bopomofo
  [0x3130,0x318F], // Hangul Compatibility Jamo
  [0x3190,0x319F], // Kanbun
  [0x31A0,0x31BF], // Bopomofo Extended
  [0x31C0,0x31EF], // CJK Strokes
  [0x31F0,0x31FF], // Katakana Phonetic Extensions
  [0x3200,0x32FF], // Enclosed CJK Letters and Months
  [0x3300,0x33FF], // CJK Compatibility
  [0x3400,0x4DBF], // CJK Unified Ideographs Extension A
  [0x4DC0,0x4DFF], // Yijing Hexagram Symbols
  [0x4E00,0x9FFF], // CJK Unified Ideographs
  [0xA000,0xA48F], // Yi Syllables
  [0xA490,0xA4CF], // Yi Radicals
  [0xA4D0,0xA4FF], // Lisu
  [0xA500,0xA63F], // Vai
  [0xA640,0xA69F], // Cyrillic Extended-B
  [0xA6A0,0xA6FF], // Bamum
  [0xA700,0xA71F], // Modifier Tone Letters
  [0xA720,0xA7FF], // Latin Extended-D
  [0xA800,0xA82F], // Syloti Nagri
  [0xA830,0xA83F], // Common Indic Number Forms
  [0xA840,0xA87F], // Phags-pa
  [0xA880,0xA8DF], // Saurashtra
  [0xA8E0,0xA8FF], // Devanagari Extended
  [0xA900,0xA92F], // Kayah Li
  [0xA930,0xA95F], // Rejang
  [0xA960,0xA97F], // Hangul Jamo Extended-A
  [0xA980,0xA9DF], // Javanese
  [0xA9E0,0xA9FF], // Myanmar Extended-B
  [0xAA00,0xAA5F], // Cham
  [0xAA60,0xAA7F], // Myanmar Extended-A
  [0xAA80,0xAADF], // Tai Viet
  [0xAAE0,0xAAFF], // Meetei Mayek Extensions
  [0xAB00,0xAB2F], // Ethiopic Extended-A
  [0xAB30,0xAB6F], // Latin Extended-E
  [0xABC0,0xABFF], // Meetei Mayek
  [0xAC00,0xD7AF], // Hangul Syllables
  [0xD7B0,0xD7FF], // Hangul Jamo Extended-B
  [0xF900,0xFAFF], // CJK Compatibility Ideographs
  [0xFB00,0xFB4F], // Alphabetic Presentation Forms
  [0xFB50,0xFDFF], // Arabic Presentation Forms-A
  [0xFE00,0xFE0F], // Variation Selectors
  [0xFE10,0xFE1F], // Vertical Forms
  [0xFE20,0xFE2F], // Combining Half Marks
  [0xFE30,0xFE4F], // CJK Compatibility Forms
  [0xFE50,0xFE6F], // Small Form Variants
  [0xFE70,0xFEFF], // Arabic Presentation Forms-B
  [0xFF00,0xFFEF], // Halfwidth and Fullwidth Forms
  [0xFFF0,0xFFFF], // Specials
  [0x10000,0x1007F], // Linear B Syllabary
  [0x10080,0x100FF], // Linear B Ideograms
  [0x10100,0x1013F], // Aegean Numbers
  [0x10140,0x1018F], // Ancient Greek Numbers
  [0x10190,0x101CF], // Ancient Symbols
  [0x101D0,0x101FF], // Phaistos Disc
  [0x10280,0x1029F], // Lycian
  [0x102A0,0x102DF], // Carian
  [0x102E0,0x102FF], // Coptic Epact Numbers
  [0x10300,0x1032F], // Old Italic
  [0x10330,0x1034F], // Gothic
  [0x10350,0x1037F], // Old Permic
  [0x10380,0x1039F], // Ugaritic
  [0x103A0,0x103DF], // Old Persian
  [0x10400,0x1044F], // Deseret
  [0x10450,0x1047F], // Shavian
  [0x10480,0x104AF], // Osmanya
  [0x10500,0x1052F], // Elbasan
  [0x10530,0x1056F], // Caucasian Albanian
  [0x10600,0x1077F], // Linear A
  [0x10800,0x1083F], // Cypriot Syllabary
  [0x10840,0x1085F], // Imperial Aramaic
  [0x10860,0x1087F], // Palmyrene
  [0x10880,0x108AF], // Nabataean
  [0x10900,0x1091F], // Phoenician
  [0x10920,0x1093F], // Lydian
  [0x10980,0x1099F], // Meroitic Hieroglyphs
  [0x109A0,0x109FF], // Meroitic Cursive
  [0x10A00,0x10A5F], // Kharoshthi
  [0x10A60,0x10A7F], // Old South Arabian
  [0x10A80,0x10A9F], // Old North Arabian
  [0x10AC0,0x10AFF], // Manichaean
  [0x10B00,0x10B3F], // Avestan
  [0x10B40,0x10B5F], // Inscriptional Parthian
  [0x10B60,0x10B7F], // Inscriptional Pahlavi
  [0x10B80,0x10BAF], // Psalter Pahlavi
  [0x10C00,0x10C4F], // Old Turkic
  [0x10E60,0x10E7F], // Rumi Numeral Symbols
  [0x11000,0x1107F], // Brahmi
  [0x11080,0x110CF], // Kaithi
  [0x110D0,0x110FF], // Sora Sompeng
  [0x11100,0x1114F], // Chakma
  [0x11150,0x1117F], // Mahajani
  [0x11180,0x111DF], // Sharada
  [0x111E0,0x111FF], // Sinhala Archaic Numbers
  [0x11200,0x1124F], // Khojki
  [0x112B0,0x112FF], // Khudawadi
  [0x11300,0x1137F], // Grantha
  [0x11480,0x114DF], // Tirhuta
  [0x11580,0x115FF], // Siddham
  [0x11600,0x1165F], // Modi
  [0x11680,0x116CF], // Takri
  [0x118A0,0x118FF], // Warang Citi
  [0x11AC0,0x11AFF], // Pau Cin Hau
  [0x12000,0x123FF], // Cuneiform
  [0x12400,0x1247F], // Cuneiform Numbers and Punctuation
  [0x13000,0x1342F], // Egyptian Hieroglyphs
  [0x16800,0x16A3F], // Bamum Supplement
  [0x16A40,0x16A6F], // Mro
  [0x16AD0,0x16AFF], // Bassa Vah
  [0x16B00,0x16B8F], // Pahawh Hmong
  [0x16F00,0x16F9F], // Miao
  [0x1B000,0x1B0FF], // Kana Supplement
  [0x1BC00,0x1BC9F], // Duployan
  [0x1BCA0,0x1BCAF], // Shorthand Format Controls
  [0x1D000,0x1D0FF], // Byzantine Musical Symbols
  [0x1D100,0x1D1FF], // Musical Symbols
  [0x1D200,0x1D24F], // Ancient Greek Musical Notation
  [0x1D300,0x1D35F], // Tai Xuan Jing Symbols
  [0x1D360,0x1D37F], // Counting Rod Numerals
  [0x1D400,0x1D7FF], // Mathematical Alphanumeric Symbols
  [0x1E800,0x1E8DF], // Mende Kikakui
  [0x1EE00,0x1EEFF], // Arabic Mathematical Alphabetic Symbols
  [0x1F000,0x1F02F], // Mahjong Tiles
  [0x1F030,0x1F09F], // Domino Tiles
  [0x1F0A0,0x1F0FF], // Playing Cards
  [0x1F100,0x1F1FF], // Enclosed Alphanumeric Supplement
  [0x1F200,0x1F2FF], // Enclosed Ideographic Supplement
  [0x1F300,0x1F5FF], // Miscellaneous Symbols and Pictographs
  [0x1F600,0x1F64F], // Emoticons
  [0x1F650,0x1F67F], // Ornamental Dingbats
  [0x1F680,0x1F6FF], // Transport and Map Symbols
  [0x1F700,0x1F77F], // Alchemical Symbols
  [0x1F780,0x1F7FF], // Geometric Shapes Extended
  [0x1F800,0x1F8FF], // Supplemental Arrows-C
  [0x20000,0x2A6DF], // CJK Unified Ideographs Extension B
  [0x2A700,0x2B73F], // CJK Unified Ideographs Extension C
  [0x2B740,0x2B81F], // CJK Unified Ideographs Extension D
  [0x2F800,0x2FA1F], // CJK Compatibility Ideographs Supplement
  [0xE0000,0xE007F], // Tags
  [0xE0100,0xE01EF]  // Variation Selectors Supplement
]

Total: 116,816 code points.

Scoring
--

Your score is the number of bytes that your encoder outputs when you feed it with all the 116,816 possible code points (in one time or separately).

\$\endgroup\$
3
  • \$\begingroup\$ I suppose 317754 is the optimal score, right? \$\endgroup\$
    – DELETE_ME
    Oct 22, 2018 at 9:37
  • \$\begingroup\$ @user202729 Yes if there are 116,816 code points \$\endgroup\$
    – l4m2
    Oct 22, 2018 at 9:38
  • 1
    \$\begingroup\$ p.s. I think you should expand it while it is on the sandbox, just in case somebody don't understand the specification. \$\endgroup\$
    – DELETE_ME
    Oct 22, 2018 at 9:38
-2
\$\begingroup\$

Forcing a kernel panic from a mountaintop

This is a thought resulting from a curious incident where C# code opening file apparently caused a BSOD. In the conclusion, it was due to a faulty driver, but from that a thought came up --- can one cause a kernel panic (or BSOD) using managed code exclusively?

Why?

Typically in such environment, there are many compile-time and run-time checks that safeguard the code from doing something that would cause a kernel panic. For a mature managed environment, it should be impossible to cause the operating system to arrive into a bad state. In the case, though it was C# code, the fact that a faulty driver was involved breached the walled garden. But can we breach it from within?

Rules

  • The code must be managed in some fashion (e.g. Java, C#, VB.NET), and normally comes with both compile-time and run-time checks.
  • The code should be running in a virtual machine or equivalent. (e.g. Java's JVM or .NET's AppDomain)
  • The code should NOT rely on any external anything. No extern declarations, no networking, no dodgy APIs.
  • The code should NOT use any construct which allow direct access to resources (e.g. unsafe in C#)
  • The code should use only the native libraries & API available as part of its usual environment.
  • Throwing an exception is not sufficient. To qualify, the code must result in a kernel panic.

Criteria

Essentially a code-golf -

  • The less code to kernel panic, the better
  • The fewer dependencies the code uses to make it happen, the better
  • The code that consistently causes a kernel panic is better than one that only does it sometimes
\$\endgroup\$
3
  • 2
    \$\begingroup\$ Is the code considered malicious code? \$\endgroup\$
    – DELETE_ME
    Nov 10, 2018 at 15:26
  • \$\begingroup\$ What is "managed code"? \$\endgroup\$
    – DELETE_ME
    Nov 10, 2018 at 15:26
  • \$\begingroup\$ While it can be used with malicious intent, the goal is more toward proving whether it's possible to unintentionally break through the walled garden. RE: "managed code" --- it might be a .NET-specific term but I use it in general sense to refer to any programming language that usually run in a some kind of sandbox -- I cited Java's JVM or .NET's AppDomain as such examples. Those usually enforce runtime checks in addition to compile-time checks to prevent doing stupid thing like passing a null pointer which usually is a trappable exception. \$\endgroup\$
    – this
    Nov 10, 2018 at 19:06
-2
\$\begingroup\$

Play snake on a 50*50 grid. The snake will start at length 3, heading (2,0) with body (1,0) and (0,0). It shouldn't bump into wall or itself. There is always one food, which increases the length of snake by 1 when eaten.

Smallest amount of steps till there's no space to place food win. Flexible I/O, anyway it doesn't matter.

Vote on whether the food placer is transparent and allow food manipulation(Up for yes, down for no)

\$\endgroup\$
4
  • \$\begingroup\$ I think there are already quite a few snake challenges. You need to flesh out some more details here. How do you determine where the food will spawn? Will you be given some sampling of the game state (vision?) on each step? \$\endgroup\$
    – Beefster
    Dec 28, 2018 at 19:22
  • \$\begingroup\$ @Beefster If "food placer is transparent and allow food manipulation", you just know how it spawns; If not, you get access to the location of current food \$\endgroup\$
    – l4m2
    Dec 29, 2018 at 3:44
  • \$\begingroup\$ If food manip. is allowed, is the optimal score achievable by finding an Hamiltonian path starts with the snake? \$\endgroup\$
    – DELETE_ME
    Dec 29, 2018 at 8:55
  • \$\begingroup\$ @user202729 It depends on how strong the manipulation is \$\endgroup\$
    – l4m2
    Dec 29, 2018 at 10:54
-2
\$\begingroup\$

No-alphanumeric code exec

\$\endgroup\$
6
  • 4
    \$\begingroup\$ -1 for winning entries must be written in one of the 25 top languages. \$\endgroup\$
    – Jo King Mod
    Jan 19, 2019 at 9:28
  • \$\begingroup\$ I'm trying to exclude golfing languages with that - this only seems like an interesting challenge to me if you don't allow languages where it's excessively trivial. Any suggestions for how to do that in a more permissive way or other thoughts about that goal? \$\endgroup\$
    – lahwran
    Jan 19, 2019 at 22:13
  • \$\begingroup\$ actually, I think this will be quite difficult in many code golf languages as well, as they usually try to get brevity by cramming things into single letters and numbers. there are of course languages where it'll be excessively trivial, but that's fine, those solutions most likely just won't be upvoted. \$\endgroup\$
    – lahwran
    Jan 19, 2019 at 22:21
  • \$\begingroup\$ Most golfing languages won't be able to pull sth. from the interconnected-webs afaik, so there's no real need to invent arbitrary restrictions to ban them. \$\endgroup\$ Jan 21, 2019 at 16:25
  • 1
    \$\begingroup\$ Also "but that's fine, those solutions most likely just won't be upvoted" is too optimistic, usually it's the other way around :( \$\endgroup\$ Jan 21, 2019 at 16:26
  • \$\begingroup\$ dang, good to know. \$\endgroup\$
    – lahwran
    Jan 21, 2019 at 22:55
-2
\$\begingroup\$

HTML-tac-toe

Build a one-player tic-tac-toe game with only HTML and CSS.

Introduction

You can do just about anything with a fully-featured programming language, but how much can you accomplish on a Neopets petpage? Inspired by http://www.neopets.com/~vuh

Challenge

Build a one-player tic-tac-toe game with only HTML and CSS.

  • Use no more than one file.
  • GIFs (including animations), PNGs, and JPEGs are allowed.
  • Flash, embedded scripts, iframes, and JavaScript are not allowed.
  • It must work in the at least two standard browsers (FF, Chrome, Safari, Opera, IE)

Inputs: The player will click on a space when it's their turn to move there.

Outputs: The page will show the current board state at all times. The page will play an optimal move whenever the player moves, unless the game is over.

You're free to decide who starts and who has X or O.

Scores

  • -10 per image
  • -1 per opening bracket or brace (< / { )

Brownie points for design, flair, and new tricks!

Example Input and Output

Input:

Click on the top left of an empty grid

Output:

Grid shows my mark where I clicked and the opposite mark in the left middle or top middle.

\$\endgroup\$
11
  • \$\begingroup\$ I'd recommend against restricting languages, and against score bonuses too \$\endgroup\$
    – ASCII-only
    Jan 22, 2019 at 4:15
  • \$\begingroup\$ @ASCII-only I can drop the bonuses without much consequence, but it's not a new challenge without a language or host restriction. Any suggestions? \$\endgroup\$
    – Qaz
    Jan 22, 2019 at 4:45
  • \$\begingroup\$ True, but... language restrictions are pretty frowned upon \$\endgroup\$
    – ASCII-only
    Jan 22, 2019 at 4:47
  • 1
    \$\begingroup\$ Welcome to PPCG! You may want to check this post out, it certainly helped me when starting with writing my own challenges. Also, your post does not have a well-defined objective winning criterion. It seems like it is atomic code-golf or code-challenge [1/2] \$\endgroup\$ Jan 22, 2019 at 19:32
  • \$\begingroup\$ , but you will need to define how answers are scored (in this case lower is worse) and how ties are treated. Also why do you disallow GIFs but JPGs not? I know most will know, but maybe explain or at the very least link to somewhere where the rules for tic-tac-toe are explained. What counts as an X, what as an O? There are a lot of open question atm. [2/2] \$\endgroup\$ Jan 22, 2019 at 19:36
  • \$\begingroup\$ JPGs are allowed. (That's the same format as JPEG, just a different extension.) I can change it to 'images', but I'm worried about some image format I don't know of that makes the challenge trivial. More points, more better! That seems clear enough, but I can certainly spell it out. Are ties forbidden? Two entries with the same number of points seem equally good to me, but the first posted could be the winner. If I link to tic-tac-toe rules, does that answer "What counts as an X, what as an O?" or are you asking something else? \$\endgroup\$
    – Qaz
    Jan 23, 2019 at 0:13
  • 4
    \$\begingroup\$ "Standard exceptions are allowed IF they work on Neopets.com." How do we know what works on Neopets.com? If we have to create accounts on a random third party site to test answers and know whether they're valid or not, the question should and probably will end up closed with a lot of downvotes. \$\endgroup\$ Jan 24, 2019 at 15:34
  • 1
    \$\begingroup\$ This isn't very interesting in general. It essentially amounts to creating every possible layout of a tic-tac-toe board and linking them together with clever CSS and HTML hacks so it fits in 25 pages. I think it could be made a bit more interesting by making it atomic code golf scoring on the total number of html files used, lowest scores win rather than limiting the total number of pages. \$\endgroup\$
    – Beefster
    Jan 25, 2019 at 20:36
  • \$\begingroup\$ @PeterTaylor very well, dropped that altogether \$\endgroup\$
    – Qaz
    Jan 25, 2019 at 22:53
  • \$\begingroup\$ @Beefster The page I link to as the inspiration (neopets.com/~vuh) uses only one html file, and the source isn't too hard to understand, so perhaps I should link to the creator of the page instead, limit the solutions to one page, or both. \$\endgroup\$
    – Qaz
    Jan 25, 2019 at 22:53
  • 1
    \$\begingroup\$ I highly suggest looking through current codegolf questions to see which are well-received by the community. This question seems highly arbitrary and leaves too much under-specified. \$\endgroup\$
    – qwr
    Jan 27, 2019 at 20:28
-2
\$\begingroup\$

Bit flipper

Given a string s and a positive number n, return the string s with n random bits flipped. (A random number can be generated in any way, including pseudo-random number generators)

Example:

Before:

Hello World

After (n = 2, 2 bits flipped):

Hello wOrld
\$\endgroup\$
16
  • 2
    \$\begingroup\$ How exact are the bytes being 'flipped'? Are we changing the bits? Is the output deterministic? It doesn't look like you're modifying any specific bit of the byte, or reversing it, or doing bitwise negation. \$\endgroup\$
    – Riker
    Mar 21, 2019 at 1:55
  • 1
    \$\begingroup\$ @Riker well changing from uppercase to lowercase is just xor 32. But they'rem saying byte flipper not bit flipper which is a bit confusing \$\endgroup\$
    – ASCII-only
    Mar 21, 2019 at 6:09
  • \$\begingroup\$ @Riker The bits are flipped \$\endgroup\$ Mar 21, 2019 at 9:42
  • \$\begingroup\$ @JoKing No, that was an example because I didn’t wanted binary non-unicode characters in the post. \$\endgroup\$ Mar 21, 2019 at 9:44
  • \$\begingroup\$ What is n? On the basis of what little is specified in the question, I would be tempted to write an implementation for n=0 which consists of the empty program in GolfScript... \$\endgroup\$ Mar 21, 2019 at 16:44
  • \$\begingroup\$ @PeterTaylor A user defined count of how many bytes will be flipped \$\endgroup\$ Mar 21, 2019 at 18:12
  • 1
    \$\begingroup\$ I think the confusion here is that "bytes" doesn't mean what you think it means. From the lone test case I think what you're trying to ask us is: given a string s and a number n, change the case of n random letters in s - would that be correct? \$\endgroup\$
    – Shaggy
    Mar 22, 2019 at 0:41
  • \$\begingroup\$ I assume case was just an example of bit 5 flipping. I'd recommend writing it like Given a string s and a positive number n, return the string s with n random bits flipped. Though from there you run into problems about invalid unicode sequences in the output \$\endgroup\$
    – Jo King Mod
    Mar 22, 2019 at 3:45
  • \$\begingroup\$ @JoKing I replaced with your example. \$\endgroup\$ Mar 22, 2019 at 7:47
  • \$\begingroup\$ What do you mean by Default n = 3? Also, how should programs handle invalid unicode sequences? \$\endgroup\$
    – Jo King Mod
    Mar 22, 2019 at 9:14
  • \$\begingroup\$ @JoKing By default, n should be 3. And invalid unicode sequences should not be handled, and the data should be directly printed out to stdout or any output file. \$\endgroup\$ Mar 22, 2019 at 12:35
  • \$\begingroup\$ When you say random, do you mean of our choice? pseudo-random? fetched from random.org? \$\endgroup\$
    – Miriam
    Mar 26, 2019 at 23:16
  • \$\begingroup\$ @ArtemisFowl It is selected by the program. \$\endgroup\$ Mar 27, 2019 at 10:45
  • \$\begingroup\$ @smileycreations15 It's gonna be hard to make that 100% random \$\endgroup\$
    – Miriam
    Mar 27, 2019 at 15:46
  • 1
    \$\begingroup\$ @smileycreations15 Maybe you should add that to the question. \$\endgroup\$
    – Miriam
    Mar 27, 2019 at 20:35
-2
\$\begingroup\$

You can't tell me what to do!!!

Intentionally break as many coding conventions as possible while crafting a working Hello World

For each language, a coding convention standard will be selected. The following is the current list:

javascript -> Google's Style Guide

PHP -> PSR-2

C++ -> ISO C++ Style Guide

Python -> PEP-8

The maximum file length is 6000 characters. Any code beyond the first 6000 will not count towards broken conventions. (Using conventions that you have set to break after the 6000 point, however, will count against you.)

If you do not see your language, you may choose one of the most common coding standards for your language, and use that, and (hopefully) it will be noticed and added to the list. Each language is its own competition. (For example: If your code is in Ruby, you're not competing against C++ code)

This is the coding equivalent of an ugly baby contest, and pushes you to think outside the box (possibly way too far outside the box). The goal is to write a 'simple' Hello World program. However, you have to do it while breaking as many coding conventions as possible, and being as ugly as possible (but still working!)

The advantages of this puzzle are multi-purpose. This is to challenge the coder to separate long-standing habits (which generally follow coding conventions) from functionality - to encourage creativity. Further, it also serves as a reverse example to demonstrate when coding conventions are a help vs a hindrance.

Remember, ugly doesn't have to mean gibberish or unnecessarily long or poorly running. In fact, code length or runtime do not factor into the evaluation.

For example, you could write procedural code using only classes, use an eval() to declare constants, or use only use variable names using characters that have nothing to do with what the variable does, reverse indentation, or rely exclusively on gotos in an interpreted language. The only thing your code has to do is output "Hello World" to the command line or an equivalent.

Each answer should list and link to coding conventions it breaks and receives 1 point for each broken code convention (but instant total of zero points the code follows any coding convention it says its breaking). If a voter agrees it violates all the listed coding conventions, upvote the code that violates the most while still functioning. (Accidentally violating coding conventions, however, does not count. Each one violated coding convention must be documented and intentional.)

Note: For each coding convention taken on, it must be consistently broken across the entire program. Following the convention even once invalidates your entire code. Habits are your enemy. Further note: If you declare you're breaking a convention, you MUST break it. If it's not applicable, it doesn't count.

Alternate Scoring method:

Don't like the "call your shot and then try to make it" scoring method? Do you have a readily available git functionality? Does the coding convention have a convenient git-hook for code style enforcement? Fear not, you have the option for an alternate scoring method: 1. Write up your code. 2. Run it through the git commit with the hook active. 3. If your hook auto-changes code, commit it, and do step 4. If it gives you coding style errors and rejects the commit, count the errors; you get one point for each error and skip to step 5. If you break git due to the hook crashing, list the broken code enforcement, add 50 points, and try again with a different code-enforcement hook. (You CANNOT be an author or contributor to any git-hook before you test against it. This is considered cheating and will be disqualify you.) 4. If your hook auto-changes code to fit style enforcement, do a git-diff between your code and the code it committed. Each change is one point. 5. Total your points. List your points as an alternate score in your answer's header. List the code-enforcement hooks you tested it against.

I'm personally not a fan of this scoring method as it allows accidental points and becomes more like it's testing the enforcement hook rather than creative code style breaking, but some like the more computer-controlled scoring method... so there ya go.

Sandbox Reminder: Sandbox is a place for constructive criticism. Saying, "I don't like it" or "I wouldn't do it" isn't constructive criticism. Last time I had this in the sandbox, most criticism was built on disliking the type of challenge, not actually building it properly. If you don't like the challenge concept, then just don't do it. If you have legitimate suggestions on how to make the challenge better then do so. I will do my best to address legitimate points.

Standard Example Answer format


My Oh so wrong Hello world - PHP - Attempting 2 points

Breaking conventions in PSR-2:

  • breaking "Opening braces for classes MUST go on the next line, and closing braces MUST go on the next line after the body."
  • breaking "All PHP files MUST end with a single blank line."

--

<?php
class hiworld{public $printme = "Hello World"}
$hiworld = new hiworld;
echo $hiworld->$print; 
?>

Alternate Example Answer format


My Oh so wrong and totally fake Hello world - PHP - Alt.Points(53)

<?php
class hiworld{public $printme = "Hello World"}
$hiworld = new hiworld;
echo $hiworld->$print; 
?>

Attempted with:

50 pts: PSR-2 Foo's Enforcement Hook: Foo-Checker [http://foo.example.com] (Broke)

3 pts: PSR-2 Bar's Enforcement Hook: Bar-Checker [http://bar.example.com]


Deleted Version

\$\endgroup\$
24
  • \$\begingroup\$ That just makes it better. \$\endgroup\$
    – lilHar
    Mar 8, 2019 at 23:29
  • \$\begingroup\$ Hate as measured by votes, however, is a discrete value, and therefore objective. \$\endgroup\$
    – lilHar
    Mar 8, 2019 at 23:37
  • \$\begingroup\$ While I disagree that pop cons need an objective criterion for voting (anything objectively measurable wouldn't need votes), pop cons are out of favour for that very reason. It is rare for a pop con to be welcomed. \$\endgroup\$ Mar 10, 2019 at 10:00
  • \$\begingroup\$ @trichoplax Fair enough on that. I'll change encouragement to just be on coding style. \$\endgroup\$
    – lilHar
    Mar 10, 2019 at 22:25
  • 3
    \$\begingroup\$ The problem is mostly the popularity-contest tag, which are very hard to do correctly. For example, how do you define break as many coding conventions as possible? How do you define convention, especially for esoteric languages where there are no conventions? The amount of conventions broken also depends on the poster's and viewer's standards, and is therefore not objective. \$\endgroup\$
    – Jo King Mod
    Mar 12, 2019 at 21:38
  • 1
    \$\begingroup\$ If a voter agrees it violates all the listed coding conventions, upvote the code that violates the most while still functioning is still subjective. All conventions are going to be subjective, e.g. Proper indentation, does that mean 4 spaces or a tab? One voter might think one way, and another might think another way. In general, I think you've chosen a very subjective winning criterion, and short of listing and defining the conventions yourself, it's not going to become objective again. \$\endgroup\$
    – Jo King Mod
    Mar 13, 2019 at 0:06
  • 2
    \$\begingroup\$ I've removed my downvote and the related comment. \$\endgroup\$ Mar 13, 2019 at 6:59
  • 2
    \$\begingroup\$ The new scoring mechanism is still subjective, but a big improvement. What counts as a convention still seems like a grey area. Does it need to be from an official source, for some definition of official? Does it need to have been posted online prior to the posting of this challenge? Does it need to be stating that coders "must", "should", or something else? \$\endgroup\$ Mar 13, 2019 at 7:05
  • 4
    \$\begingroup\$ One way to make this objective would be as a language specific challenge, for example with something like JSLint. That way your score is the number of complaints triggered when running it through the linter, and highest wins. Only being able to compete in one language doesn't seem ideal, but I mention it as an example in case someone can come up with a more inclusive approach. \$\endgroup\$ Mar 13, 2019 at 7:08
  • 5
    \$\begingroup\$ "Whatever makes you feel dirty for having put it through your keyboard" and "Each answer should list and link to coding conventions it breaks" are mutually contradictory. \$\endgroup\$ Mar 13, 2019 at 12:00
  • 2
    \$\begingroup\$ @trichoplax I do like your idea of counting linter complaints to make it more objective, and feel that's on the right track. Maybe bringing some code-cleanup program into it, and seeing how much work it has to do? \$\endgroup\$
    – lilHar
    Mar 13, 2019 at 15:33
  • 2
    \$\begingroup\$ I feel like this could work if one language was selected, with associated style guide/linter, and an objective scoring system made for that. Otherwise, you're comparing a lot of apples and shoes. \$\endgroup\$ Mar 14, 2019 at 16:36
  • 2
    \$\begingroup\$ I know this probably isn't going anywhere, but the most 'official' python style guide is probably PEP 8. \$\endgroup\$
    – Miriam
    Apr 6, 2019 at 18:17
  • 1
    \$\begingroup\$ @liljoshu You've got my upvote for what it's worth, though I agree this needs some improvements. \$\endgroup\$
    – Miriam
    Apr 8, 2019 at 22:35
  • 2
    \$\begingroup\$ Something like codegolf.stackexchange.com/questions/172445/… might be ok \$\endgroup\$
    – Gymhgy
    Apr 10, 2019 at 3:04
-2
\$\begingroup\$

Best Mile Time

Introduction

Your friend has been trying to improve his mile time on. Unfortunately, he isn't very good at keeping a steady pace and constantly speeds up and then slows down. He usually runs for many miles at a time and wants to choose the fastest mile of his run to determine his mile time.

Given your friend's distance versus time, determine his fastest mile time for a contiguous mile stretch.

Input

A list of distances (in miles) sampled at an even interval.

Output

The length of the smallest interval during which a distance of at least one mile was traveled.

Rules

  • You may assume that the the total distance traveled is at least 1 mile.
  • The mile time must be for a continuous time interval.
  • Standard loop-holes are forbidden.
  • Standard rules apply.
  • Please provide a link to test your code as well as an explanation.
  • This is , so the program with the smallest asymptotic time complexity wins!
  • Ties will be broken by fastest run time.

Example

Python 3.7, O(n ^ 2)

Try it online!

from typing import List


def fastest_mile_time(distances):
    """Determines the fastest mile time from a list of distances.

    Parameters
    ----------
    distances : List[float]
        The list of distances in miles.

    Returns
    -------
    int
        The length of the smallest interval during which at least one mile was traveled.
    """
    intervals = []
    for i in range(len(distances) - 1):
        for j in range(i + 1, len(distances)):
            if distances[j] - distances[i] >= 1:
                intervals.append((i, j))
                break

    return min(map(lambda x: x[1] - x[0], intervals))
\$\endgroup\$
6
  • \$\begingroup\$ @FryAmTheEggman how's this? \$\endgroup\$ Jul 19, 2019 at 2:32
  • 2
    \$\begingroup\$ Unless I'm missing something this is trivially O(n): keep two pointers into the list, advance them keeping them 1 mile apart, and keep track of the running minimum time. I'm downvoting, so ping me if I was mistaken or if this is updated so I can update my vote. \$\endgroup\$
    – lirtosiast
    Jul 19, 2019 at 2:52
  • \$\begingroup\$ @lirtosiast O(n) is trivial. I just gave O(n ^ 2) as an example. However it isn't clear to me that O(n) is the lower bound. I think the fact that the sequence is monotonically increasing may be of some use (although I've yet to show that to be the case). \$\endgroup\$ Jul 19, 2019 at 3:20
  • 3
    \$\begingroup\$ The optimal solution is O(n). You need to iterate two pointers through the entire list one time to ensure that you have found the minimum valid difference. The range of time this will take ranges from Ω(n) to O(2n) in the optimized case. for(i=j=0;j<length;i++){for(;array[j]-array[i]<1&&j<length;j++){}minTime=min(minTime , j-i)} \$\endgroup\$ Jul 20, 2019 at 17:00
  • 2
    \$\begingroup\$ Consider a list where every element at even index 2n is n, and every element at index 2n+1 is either n+.5 or n+1. If there is an integer at an odd index, the fastest mile time is 1, otherwise it's 2. But we have no way of determining this without reading all n/2 odd indices. \$\endgroup\$
    – lirtosiast
    Jul 20, 2019 at 18:17
  • \$\begingroup\$ @lirtosiast +1 thanks for such a clear example! \$\endgroup\$ Jul 21, 2019 at 6:16
-2
\$\begingroup\$

Produce a self-reproducing data structure

Write the shortest code to produce a self-reproducing list, dictionary, array, and so on and so forth. That is, when you index any one of the logically-available items that belongs to the resulting data structure that you have produced, you get the same data structure when you compare the equality between the data structure before you indexed and the data structure after you indexed.

  • In order to verify your code with automatically-provided constructions in programming languages, you should pick an operator that compares whether two values are equal (or does type-comparisons, if available).
  • If your language does not provide an equality operator, you should simulate an equality operator yourself using operators like - or other operators that do the job of comparing values (as in Acc!, where an explicit comparison operator is not provided.)

Example

This is an example of a validity/equality test of a possible solution in a Python REPL (when you have already produced a list, namely list, where it produces itself at its 0th item). This test simply compares the equality between the non-indexed list and the indexed list:

>>> list
[[...]]
>>> list[0]
[[...]]
>>> list==list[0]
True

However, if the result of the last line (the equality comparison) is not a truthy value in your language (for example False and 0 in Python), then your answer is invalid and should be improved.

Rules

  • Your program does not have to take input; neither does it have to explicitly output the data structure. However, your resulting data structure has to be accessible in some way.
  • This is a contest; the shortest answer will win.
  • No standard loopholes, please.
  • In this challenge, the values on both operands in the equality check should have the same type.
  • Your code (both your testing code and your producing code) should not produce any errors; any outputs to stderr are considered non-truthy values and demonstrates that your code is invalid.
\$\endgroup\$
13
  • 4
    \$\begingroup\$ What does "compare it" mean? There are many many types of comparison one can perform, and they don't necessarily give the same result for the same values. \$\endgroup\$ Jul 24, 2019 at 7:11
  • 5
    \$\begingroup\$ @A__ For JavaScript, is it == or ===? Either way, people will be angry. \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 13:16
  • 2
    \$\begingroup\$ @A__ Because either the challenge is trivial (['']) or you're arbitrarily restricting a language. Work on your definition of "equality operator". \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 13:46
  • 2
    \$\begingroup\$ @A__ So, basically, you want (x=[])[0]=x? No clever tricks? Just a bog-standard recursive data structure? (Though, it might be interesting in languages where those aren't allowed.) \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 14:07
  • \$\begingroup\$ @wizzwizz4 In fact, your program is a clever trick that I have not thought of. Mine is 13 bytes, yours is 11 bytes. Yes, what I want is a bog-standard recursive data structure, as long as it is not a duplicate of another question. (My program is a=[];a.push(a)) \$\endgroup\$
    – user85052
    Jul 24, 2019 at 14:10
  • 3
    \$\begingroup\$ @U10-Forward 0 bytes \$\endgroup\$
    – tjjfvi
    Jul 24, 2019 at 14:32
  • 1
    \$\begingroup\$ @tjjfvi I thought about that one, but I didn't think it'd be syntactically valid. It does, however, work. \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 15:19
  • 1
    \$\begingroup\$ @wizzwizz4 How do you know which language? \$\endgroup\$
    – tjjfvi
    Jul 24, 2019 at 15:31
  • 1
    \$\begingroup\$ @tjjfvi I just assumed it was a language where the "null" / "undefined" singleton was indexable, returning the very same value. \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 15:34
  • 1
    \$\begingroup\$ @wizzwizz4 No, JS: window.window === window :) \$\endgroup\$
    – tjjfvi
    Jul 24, 2019 at 15:38
  • 2
    \$\begingroup\$ @tjjfvi I read the challenge differently to you. I thought it meant "any one of the logically-available items". By this rule, (x={}).x=x is the shortest I can think of, other than the trivial case. \$\endgroup\$
    – wizzwizz4
    Jul 24, 2019 at 15:53
  • 1
    \$\begingroup\$ @tjjfvi Well i do it in Python so no such a thing called 0 bytes in python \$\endgroup\$ Jul 25, 2019 at 1:08
  • \$\begingroup\$ Alternative: window["window"]===window \$\endgroup\$
    – user85052
    Jul 25, 2019 at 4:06
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Recursive Sum Up The Digits

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Produce the shortest code that sums up all the digits in a number, and after if it still has more than one digit, sum it up again and again until it's with one digit, example: 987 would become 6 since 9 + 8 + 7 is 24, whereas 2 + 4 is 6.

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    \$\begingroup\$ I have the feeling I've seen this challenge before, but I'm unable to find it. It could be that I'm confusing it with two similar loose challenges, since there are more challenges where we continue doing something until a single digit remains, and there are also loads of challenges summing the digits of an integer. I'm not 100% sure anymore whether there is already one with both combined. \$\endgroup\$ Aug 5, 2019 at 6:37
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    \$\begingroup\$ This is just "Given n output n % 9". \$\endgroup\$ Aug 5, 2019 at 7:46
  • \$\begingroup\$ @PeterTaylor Ah, now I remember where I've seen it before: here in the sandbox, and you (or someone else) made that same comment. :) \$\endgroup\$ Aug 5, 2019 at 12:24
  • \$\begingroup\$ Isnt this just a duplicate of codegolf.stackexchange.com/q/1775/87923? \$\endgroup\$
    – EdgyNerd
    Aug 6, 2019 at 8:19
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    \$\begingroup\$ @EdgyNerd It's related, but not a dupe. That challenge takes multiple integers as input simultaneously, instead of a single input. And it outputs the amount of iterations for each of those integers to become a single digit, instead of the resulting digit itself. In addition, it has rather cumbersome output-format.. So that challenge would result in 987 2 for input [987]. The core part of both challenges is the same though: continue summing the digits of an integer until a single digit remains. \$\endgroup\$ Aug 6, 2019 at 9:16
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