Sandbox for Proposed Challenges

Question

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".

Answer 1

Is it cat-urday?

Caturday is one of the oldest memes out there. For this challenge you need to write a program that outputs the input, but only on Saturday.

The catch:

You can acquire the date via UNIX timestamp, or as a formatted date string (local or UTC). However, you can not:

• use day of the week information in a date string
• directly acquire the day of the week of a date by some other means
• use Date or Calendar functions, beyond one to simply give you the current date
• use any external resources (files, Internet)

Don't forget leap years!

code-golf

---

Does this question work as is? Should I make anything clearer?

Answer 2

Output the infinite sequence of middle positions of odd square numbers code-golf

As everyone knows, every odd square number has an element at its central position — I represent those central elements as an *:

n=1 => 1
*

n=9 => 5
###
#*#
###

n=25 => 13
#####
#####
##*##
#####
#####

n=49 => 25
#######
#######
#######
###*###
#######
#######
#######

The challenge consists on output the sequence 1, 5, 13, 25, ... uninterruptedly. The separator does not need to be a comma, but use the same separator always.

There will not be any accepted answer, except if I see some very creative answer. There will be a winner for each language (I will steal Leader board code somewhere)

code-golf math sequence

Answer 3

Hello, Quine! code-golfquinehello-worldrestricted-source

Your task is to write a program which, if given an input of "Hello," will output "Hello, world!", if given any other input, it will output its source code.

---

Rules

• Input does not have to be case-sensitive.
• Your program may not contain the string "Hello, world!" or any variation with different cases of letters (i.e "hELLO, WORLD!", "HeLlO, WoRlD!", and "hello, world!").
• No "cheating quines."
• Standard loopholes are strictly forbidden.

---

This is code-golf, so may the shortest code win and the best programmer prosper...

Answer 4

Complicating Simple Maths code-golf

We do know what 1 + 1 is, or 2 - 1. How about we turn those and other really simple operations into complex numbers?

Goal:

As stated in the intro, taking an operation that can be done within the range of the following operators ( +, -, /, *, ^ and () ), print out a complex number operation that is pretty much a transformed version, and when done using the order of operations, results in the same answer as the inputted operation.

Examples:

Input: 5 - 1
Output: 5 + 2i

Input: 4 * (7 ^ 2)
Output: (4 * 4i) * (7 ^ 2) 

Rules:

• It is recommended you print out the sector(s) that holds your complex number(s) as a + bi, e.g. (a + bi) - (ci * (di ^ f)). (NOTE: If you are doing non-communicative operations, such as ^, /, or -, the recommendation doesn't apply to the sub-operation).

• No standard loopholes.

• If you want to, feel free to use operations/functions other than the set mentioned in the Goal, but your input operation must have at least one of them.

• You can format your operators in any way, e.g. x or • instead of *, ÷ instead of /, etc.

• Input and output is allowed in any format as long as it fits within the standard I/O rules.

• Input must also be flexible (as in to return any input from a simple operation to a complex number operation.

• This is code-golf, so shortest answer wins.

Sandbox use only:

Is there any way I can improve this challenge? Are there any other loopholes to be covered in the rules?

Answer 5

The Self-Referential Algorithm

Most people are familiar with Tupper's self-referential formula. When the formula is graphed on a calculator it magically graphs itself. Wouldn't it be interesting if we could do something similar with a programming language?

Your task

Write a small program that will be able to output exactly itself when ran.

This is a code-golf question so answers will be scored in bytes, with the fewest bytes winning.

Answer 6

Pascal's Particulars

Pascal is feeling very particular today. He wants to get an element from his famous triangle without going through the work of generating all the prior elements. He'll provide you with a row number and an entry number and you'll provide him with the element at that location.

Example:
Input row = 1, entry = 1, output 1. (row 1 is 1)
Input row = 3, entry = 2, output 2. (row 3 is 1-2-1)
Input row = 6, entry = 3, output 10. (row 6 is 1-5-10-10-5-1)

Rules

• You will only be provided valid inputs (i.e. x will never be higher than n).
• Your code should either print or return the output value, either works.
• Standard golfing rules apply (lowest byte-count wins, etc.).

Happy golfing!

Answer 7

Break this block

Your challenge is to break this block.

But of course that would be a pretty easy challenge, that's why this is a cops-and-robbers challenge.
The robber's challenge: Break the block. As breaking qualifies everything that has the result that no diamond block is at the coordinates 0 128 0 (even pushing it with a piston) and that follows the rules (see below).
The cop's challenge: Prevent the robbers from breaking the block. As preventing the breaking counts everything that guarantees that there is a diamond block at 0 128 0 in every future game tick despite the robber attempting his solution (and also if he doesn't). You are not in the world while the robber makes his attempt, so you have to prepare the world for him.

Rules

• You may not use modded Minecraft or external tools that change the save file. Reading it with external tools is allowed.
• You have to show a reproducible way to break/secure the block. Just uploading a world save without saying what you changed is invalid. You should offer a detailed explanation and preferably more (video, screenshots, structure file, etc.), if necessary.
• This challenge starts with a normal world (default generation, Creative+cheats, random seed), where one diamond block was placed using the command
  /setblock 0 128 0 diamond_block
  The spawn chunks can include 0 0, but they don't have to. Since both sides have access to commands, that shouldn't matter anyway.

Sandbox questions

• How should I restrict the version? Should it be "latest release", "any stable release", "only 1.12.1", "any snapshot, release or historical version" or something else? People could come up with interesting solutions using past versions (maybe even past snapshots that aren't selectable in the launcher anymore), but I have to somewhat restrict it. If a certain downgrade automatically breaks the block, it's of course boring, especially since they instantly win. And if they load the world in any of the 9 oldest versions in the launcher (called "Classic" and "pre-Classic), there isn't even a diamond block in the game, so it would be deleted.
• Should I discourage people from instantly preventing every single breaking method with their first "cops" post? To have an interesting challenge, it should slowly become more difficult. If I should discourage it, how to "enforce" it?
• What other rules do I need?
• I'm planning to be very active myself on the "cops" side (I already have some nice ideas), possibly creating the majority of posts there. Is there a problem with that? If no, would it be considered unfair or boring to ask the others to wait up to a day with their solutions? Of course they don't have to do it, I just originally planned this to create programming challenges for myself.
• If every answer on one side can have multiple answers on the other side, which itself could have answers on the first side and so on, that could lead to a tree-like structure. But such a structure would lead to many unanswered questions (if it doesn't keep growing exponentially, what I highly doubt). Is there a way to prevent that or should I even try it?
• Apparently this is the first Minecraft-only programming challenge here. Should a minecraft tag be created for it?

Answer 8

The Compressor

code-challenge test-battery

You are given this list of 100 positive integers that are at between 7 and 18 digits long:

[list to come]

You need to generate 100 snippets that will produce these numbers in some language (either as a numeric or string). Your score is the total length of the snippets. Lowest score overall wins, but you should also try to get the lowest score in whichever language your snippets are in. Please include both your snippets and any code you used to generate them in your submission. Note: the generating code isn't actually scored.

Rules

• The snippets must all be in one language, however it does not need to be the same language as the generating program(s).
• You may assume that any pre-existing libraries you use are already imported.
• You don't need to include the line terminator (i.e ';' in Java and others) for snippets that fit on one line. For multi-line snippets, you don't need to put a terminator on the last line.

Examples

• 1357000 => 1357e3 (many languages)
• 1234567 => 1234567 (most languages)
• 307422089600 => S6*99b (CJam, returns value of [32,32,32,32,32,32] in base 99)
• 12582912 => 12<<20 (JS + others)

---

Alternative: code-golf

I generated this 100 digit random number with random.org:

7160708104901559695507628057638725214364226867212714872539720713967912042100814603497742352846014272

Write the shortest possible program that outputs this number.

---

Related: No strings (or numbers) attached

Questions? Clarifications?

Answer 9

Ulam spiral 2

Like Ulam, I had a boring moment and began drawing a spiral like him's. But his version is utterly incorrect, as the \ diagonal distorts the equation n^2.

The following picture illustrates an wrong Ulam spiral at left and a correct at right:

I challenge you to output a numbered Ulam spiral, the right version, where it is mandatory to highlight the primes. The input is n, meaning the point where the spiral ends. For the image example I gave n was 100. It will always begin at 1

I don't care what highlight style you use (different color, font weight, circle around number, etc), given it makes the primes easily distinguishable form the rest.

There will be no accepted answer; just did it for fun.

graphical-output math sequence primes number integer

Answer 10

Looking for some help to make this code golf/question better.

Proposal:

Now that twitter has increased it's character limit from 140 to 280, there's a joke of almost enough to write Hello World! in Java. But what actual programs could you write in 280 characters, fizz buzz? Sure you could write many in 140 or less, but maximum points if you get a good program in the full 280.

Answer 11

Shortest golang code to println the first byte of a function’s code

Rules

• The code must be a function which takes another function as parameter and will print the first cpu instruction byte of parameter such as :

.

func dummy() {
}
print_first_native_instruction_byte(dummy)

would print :

0x90

which is a nop instruction on x86.

• You don’t need to perform disassembling : if the first instruction is longer than one byte, just print it’s first byte anyway without caring about instruction meaning or instruction length. Please note this is harder than just printing the value pointed by &dummy in the case of my example though.
• The function parameter must be a go function, not a cgo or assembly function.
• You can include as many golang packages as you want.
• The code need to be written in Go. A well known language developped at Google and part of the four Google’s app engines supported languages and answers should be able to run on the official go playground.

Winner

The one with the shortest code… Import statements included.

Answer 12

Preposition, not possession

code-golfstring

Enthralling background

Back in 1960s Soviet Russia, communism was the thing, and –– as we all know –– in a completely socialist society, there is ideally no personal property.

Our dear client is an author who is moving to the Soviet Union. However, as is Bolshevik custom, our client is afraid his works will be censored. That is why we are going to help this industrious author by revising his writings so that they will not be censored.

What will be censored? Any overt references to ownership.

How will we do this? Quite simply: we will replace all possession with preposition.

Let's get specific

Example

Text in parenthesis is added; text in curly-brackets is removed.

[Input]   All the author's works will be censored!
[Output]  All (the works of )the author{'s works} will be censored!

Algorithmically

1. For each word with a 's attached to it:
2. Call the word with an 's attached to it _word_
3. Call the following word _object_
4. Remove all 'ss and _object_
5. Insert The _object_ of two words before _word_
6. If there are not two words before _word_, place _object_ right before _word_.

Here are some more examples:

Then the red horse stopped and took the orangutang's oranges. What a fuss ensued!
Then the red horse stopped and took the oranges of the orangutang. What a fuss ensued!

It is the people's right to not own anything!
It is the right of the people to not own anything!

The world's tallest building was once the Empire State Building.
The tallest of the world building was once the Empire State Building.

Bill likes Fred's shoes, and Jill likes Beth's dress.
Bill likes the shoes of Fred, and Jill likes the dress of Beth.

Ryan's fear was a stack overflow.
The fear of Ryan was a stack overflow.

Answer 13

Output the first digit of Graham's number

Code golf

Write a program that will output the first digit of Graham's number (and nothing else), terminate and produce no error.

I'll be lenient about loopholes. But if your submission is something like print("4"), the burden of proof will be on you.* Also, if you submit 9 answers like that, each printing one digit, then yes, one will definitely be correct, but I will need to know which one, and, you guessed it, the burden of proof is on you.*

* Catch: at the moment, no one has yet worked out what the first digit of Graham's number is.

But I want a "practical" solution. Yes, the algorithm is simple, but I'm sure your computer doesn't have unlimited storage. Nor do language implementations have arbitrarily large int. (OK, some do, but there is memory constraint.)

However, you will have a tape device attached to your computer. The library which is automatically loaded into the interpreter or compiler controls the tape device. Here things do become theoretical: the tape has a beginning, but no end, or you can imagine the device will manufacture more tape to extend it if more is needed. The tape has discrete positions. On each position a sector is stored. The device has access to one sector at the time but it can move the tape. All sectors have the same size.

The library provides you with the following functions (subroutines, whatever):
- detect if the tape is at the beginning
- move the tape left by n positions (stops at the beginning if sent beyond)
- move the tape right by n positions (n has to be one of atomic integer types of your chosen language)
- read the whole sector at current position
- read a part of the sector (zero indexed location within the sector and number of bytes to be read are arguments of an atomic integer type)
- overwrite the whole sector
- overwrite a part of the sector

The names of functions are your choice, as is the size of a sector. Reading loads the contents into a variable / into the memory area starting with a pointer given as an argument. Similar about writing.

Because the tape is effectively infinite, you have no function to tell you the actual position on the tape, as you'd have no way to store the result on a "real" computer.

So the real parts are: computer, possibly tape device.
Theoretical parts are:
- infinite storage tape or availability of material to manufacture as much tape as needed, which may well exceed the total amount of matter in our universe
- the computer, device, tape, ... not deteriorating, getting tangled up nor power falling or anything else going wrong for the time it takes the program to complete the task, which may well exceed total lifetime of our universe.

Sandbox questions

Ideas how to improve the question... or should I abandon the idea?

Answer 14

Golf an interpreter

The challenge is to find a path from A to B, but you must also provide an interpreter for your program. The shortest interpreter wins.

Input to path finder:

A list of edges in a graph e.g.

AC
CD
DB

Output from path finder:

A list of vertices e.g. A C D B

Feel free to somewhat adjust the input/output format.

Scoring:

Your score is the number of bytes of your interpreter/compiler. The lowest score wins.

Note:

It's possible to work around the question and interpret a language that is too similar to an existing one by doing something like:

eval(input_file.replace("this never happens", ""))

I don't have a good rule to prevent this other than to ask that you don't.

Answer 15

Brainf*** Polygot

polygotbrainfuckcode-golf

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.

Answer 16

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.

Answer 17

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.

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

Answer 18

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.

popularity-contest

Answer 19

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.

gui code-golf

Answer 20

Output a Random Bit

random internet code-golf

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.

Answer 21

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]

Answer 22

♫ 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);
  }
}

Answer 23

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 popularity-contest cuz it's sometimes hard to define which is "golfing language". Also is it a duplicate?

Answer 24

(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

code-golf

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?

Answer 25

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.

Answer 26

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.

Answer 27

• 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

code-golf interpreter

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:

• Asked by me regarding my repost now..
• Another one, about reposts in general.
• Martin Ender's post about closing old questions in favor of new.

---

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 code-golf, so the shortest code in bytes for each language wins.

Answer 28

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.

quine code-bowling busy-beaver

Sandbox notes

• The "1024" may change

Answer 29

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.

Answer 30

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.