# Sandbox for Proposed Challenges

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

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
• 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 needs more feedback, but it's been ignored, you can ask for feedback in The Nineteenth Byte. It's not only allowed, but highly recommended!

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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# GitHub Gist command-line client

Create a command-line tool that publishes a list of files as one public GitHub Gist.

## Specification

The following bullet points describe the behavior of the program. If a bullet point has "must", you must implement that point. If a bullet point has "can optionally" or "should optionally" you can implement that point on your own volition.

1. It must be a complete command-line program.
2. It must use the GitHub Gists API.
3. It must post an anonymous Gist (that is, not as a GitHub user).
4. Gisted files must use the filename provided on the command-line.
5. The command-line must accept multiple positional arguments.
6. If no arguments are specified, it must print this usage to STDOUT: gist: usage: <file> [file...] verbatim then exit with code 0.
7. If something else goes wrong, it must print this message to STDERR: gist: unable to gist =( verbatim then exit with code 1.
8. If everything is successful it must print the Gist's HTML URL to STDOUT.
9. It can optionally accept a flag for description -d <description. floor(score * .9)
10. It can optionally accept a flag for private gisting -p. floor(score * .9)
11. In the case that a description flag is not used or implemented it must set the description to an empty string.

## Example Input/Output

The number before the prompt is the exit code of the previous command.

0 $gist gist: usage: <file> [file...] 0$ gist no-such-file.txt
gist: unable to gist =(
1 $gist hello.txt https://gist.github.com/anonymous/1e645596ce7bceeb1ec9 0$


## Scoring

This is a so shortest answer wins. As stated above, the following multipliers are in effect:

• (9): score = floor(score * .9)
• (10): score = floor(score * .9)
• Both (9) & (10): score = floor(floor(score * .9) *.9)
• What's up with the Example Input/Output code snippet? The editor's preview displays it correctly. Jul 27 '15 at 20:17
• For the usage, should those literal strings be used regardless of the name and invocation of the program, or should it substitute the correct invocation for the leading gist? I'm thinking particularly of cases like Java, which doesn't support hashbangs. Jul 27 '15 at 20:32
• Literal string, I think. Jul 27 '15 at 20:34
• That's a good point about Java. I think I'll remove the item about shebangs since it's unfair. Jul 27 '15 at 20:41
• If both bonuses are done, is it floor(score * .9 * .9), or floor(floor(score * .9) * .9)? Jul 27 '15 at 23:48
• Also, if the bonuses are done, do we have to make the usage string reflect that, or just print it verbatim? Jul 27 '15 at 23:50
• Output strings verbatim. And floor(floor(score * .9) * .9) for both. I'll update the question momentarily. Jul 28 '15 at 2:07
• I'm curious why this challenge is being downvoted. Jul 28 '15 at 2:28

# Golf these arrays

Gzip base64: (too long, will be added if I'll post this question).

## Rules

• You don't have to output them all. And you can output the arrays in any order. But the order of items in the arrays must be kept as is.
• You can print other arrays, which wouldn't be counted towards your score. The number of arrays you print must be no more than 10,000, and the total number of arrays, subarrays and numbers must be no more than 10,000,000.
• You can use any convenient format to represent the arrays (and the list of outputted arrays).

## Scoring

If your program or function has n bytes, and it printed k distinct arrays from the above list, your score would be n*(128/k)2. Lowest score wins.

### Problems

It looks too boring.

• It also looks too broad. Aug 8 '15 at 7:55

## The Perfect Keyboard

Back in the 1970s, keyboard designers respected the needs of programmers and languages. For example, see the IBM 2741 keyboard, designed for APL (from Wikipedia):

Today, sadly, most code golfers are forced to struggle with standard keyboards, which are badly suited to the needs of their language. This has to change!

## The challenge

1. Choose a programming language.
2. Design a keyboard, which would best suit the needs of a developer (or specifically a code golfer) in said language.
3. Post the keyboard layout as an answer.
4. Explain how your keyboard enhances the programming experience.
6. Optional - if you are the winner, start a Kickstarter project to build the thing.

This section is, of course, for the sandbox only.

I don't really expect a keyboard design which would actually improve functionality of programs in an actual serious language. I'd expect fun answers, where the keyboard design highlights soemthing fun/interesting/absurd about the language. But my expectations don't matter so much, because it's not me rating the answers, but the other users.

Example (not very good ones):

1. A Brainfuck keyboard with only 4 keys.
2. A Lisp keyboard where half the keys are parentheses.
3. A Piet keyboard - I'm sure someone will come up with something nice.

• I'm note sure if it's a valid challenge since there is no programming actually involved in answering this Sep 3 '15 at 9:28
• @Fatalize, You're right, but it is a programming-related challenge. It requires knowledge of programming languages and people may find it interesting or amusing. I may be pushing the boundaries, I don't know. Sep 3 '15 at 9:45
• I would personally be ok with that challenge but I don't know if other, more prominent users would find this challenge off-topic. Sep 3 '15 at 9:48
• Judging from this Meta post, there seems to be a fairly clear consensus that a question must involve programming to be on topic, not merely be programming related. So this question is fairly clearly not valid. Sep 3 '15 at 10:08
• You could always include programming the driver or some kind of special interface for the keyboard Sep 3 '15 at 10:28
• @BetaDecay, This challenge is about crazy creative answers. Requiring a driver implementation seems to me like a way to kill this creativity. Sep 3 '15 at 11:01
• @isaacg, trichoplax writes "I judge it by whether the answers to it demonstrate skill and determination, or just aesthetic style" - I think a good answer to this challenge requires undestdanding a language and designing something that relates to its properties. Does it qualify as "skill and determination"? I can't say I'm sure. Sep 3 '15 at 11:06
• The art/programming debate was specifically about popcon questions where the answers were programs. There's no doubt whatsoever that a popcon where the answers are just images would be an art question rather than a programming question. On the same basis, this is not a programming question, and does not belong on this site. Sep 4 '15 at 13:58
• @PeterTaylor - I don't think it's an art question. The challenge isn't to get a pretty picture of a keyboard, but to design something that suits the language in an interesting way. But I posted it here to get the communities opinion, and it seems quite clear what it is. Sep 5 '15 at 19:00
• Since I wrote that meta answer the rules on popularity contests have been tightened up, and I think that is a good thing. I stand by my answer, but I think it is right that popularity contests be judged strictly, to reflect the fact that it is very difficult to write one that is a good fit for the site. Sep 4 '16 at 11:56
• Although it's possible someone will come up with an ingenious approach to designing a keyboard, the challenge itself seems to lean towards "make me laugh" rather than "impress me". This is why I don't think this is a good fit for the site. Sep 4 '16 at 12:03
• I'd love to see what keyboards the community comes up with, but I think it would need to be hosted somewhere other than main. For things which are appealing to the PPCG community, but not quite a fit for main, there's Code Golf Chat. People often post "mini challenges" which aren't well specified enough to be challenges on main, but can end up inspiring people to write a full challenge. Sep 4 '16 at 12:06
• I think it's important to keep testing the boundaries of existing winning criteria, and to try to come up with new ones. The people who put the effort into this will have a long run of rejections, but I really hope these don't come across as "don't try". Sep 4 '16 at 12:19

This and this gave me an idea, but I'm not quite sure if this can be done at all, or if it is trivial. If it is, maybe point out how it could be changed to be interesting.

# Anti golfing - Write the longest program not repeating any character

Well, it's just what the title says. Finally you're allowed to use as much bytes as possible.

## Conditions

• The code of the program or function should not use any character that is used in the code before.

• Your program should print some sort of result to stdout, or into a file or return a value. You're not allowed to output or return the empty string or only a newline.

• Other than that your program might do anything. Read input, print lots of output, or what you can think of, but you have to explain what it does, of course.

• Only characters in the ASCII range [32 .. 126] and newlines are allowed, which limits the maximal code length to 96 bytes.

• Variable names are only allowed to consist of a single character

• String literals or the like are forbidden. They could be used to hold the unused characters (though they would need two " in most languages anyway).

• The same rule applies for similar literal constructs like blocks or what else is there in some languages.

• Even if the length of a string literal would be used to generate a number, it is forbidden.

• Variables can not just be declared and never be used. They have to be reflected in the output somehow.

• If you've read and understood the above rules and still found a loophole and used it, you should go and stand in the corner for a while, thinking about what you've done.

So all in all, only use characters for actual code that does something generating the output, might it be calculating a value or formatting. And don't put unused characters somewhere in your code as a literal. Numbers are an exception, but I guess it's no problem to use them anyway.

I guess you should have a pretty good idea of what would be considered cheating here.

Example in awk

BEGIN{gsub(a,9);print $j-13+d^c/4*5678%20}  It prints 15.5, score is 42. It replaces the empty string a with 9 in $0, which is the empty string in the beginning. So $0 becomes 9. Then it prints the result of 9-13+1/4*5678%20. ($j is $0 (==9), because j is not defined d^c ist 1, because c and d are not defined) Please don't invent languages for this ;) The longest code in bytes wins. • Are you sure you want to allow ASCII 127? That's the unprintable<DEL> character. The main problem with this challenge is "only use characters for actual code that does something". This is essentially unenforceable, because there may be arbitrarily complicated no-ops in the code. It's also why most code-bowling challenges fail to be popular/interesting. Sep 14 '15 at 7:32 • Well, I thought about making it a "most votes win" challenge, but I guess that would be unfair for less known users. I don't know what could be done with what you are pointing out. Sep 14 '15 at 7:51 • I don't think this is a good candidate for a popularity contest. Popularity contests shouldn't be used as a cop out if the actual spec is a bit vague. They work best for challenges where the actual scoring criterion can be well specified but is more easily judged by humans than machines (e.g. "visually approximate a given image with these constraints..."). Sep 14 '15 at 7:54 • Yeah, it's hard to formulate the rules for this. But I think it's not always about finding a winner anyway. Thought this might be fun. Resolved the character 127 situation btw.. Sep 14 '15 at 7:57 • How could I change that rule? I'm thinking about "only use code that contributes to the generation of the output" Sep 14 '15 at 8:02 • How do you define "contribute"? E.g. this GolfScript program prints the length of the block in {...} which is a convenient way to stuff all characters except in '"# in there. Do all those random characters actually contribute? In Slashes everything which isn't an unescaped slash is printed to STDOUT, so as long as I put \/ together, I can put any characters I want there and they'll all contribute. Sep 14 '15 at 8:07 • Hmm, I thought this would be covered by forbidding string literals.. might think about extending that rule to blocks. Well, I'm not that fluent at esolangs. Sep 14 '15 at 8:10 • It's trivial to use all possible 96 bytes. Trust me. If you really want to see the program I'm thinking of, I suppose I could write it, but I'm pretty sure it can be done. Sep 16 '15 at 18:34 • Yeah, I guess you're right. i have no idea how it would be done, but alright. Sep 16 '15 at 20:10 • Not to mention this is pretty much a duplicate of codegolf.stackexchange.com/questions/30159/… Aug 6 '17 at 12:52 # Technologic - Now what's THAT command do?? Daft Punk's song "Technologic" is all about actions that a user or computer does when it's working and being used. You goal is to write a program that has one command we will call the Technologic Command. This command will executes all of the actions like "buy it", "lock it", "code it", and "write it" in the order the lyrics are written on 'it'. What 'it' is is up to you, but you gotta let me know. # Rules • Any language can be used. • The song refers to an 'it'. That can be a block a memory, algorithm, function, file, or anything else a computer can manipulate directly or indirectly. • You must specify what 'it' is you will be performing these actions on. If you don't, you can only earn a maximum of 160 points. • Points will be deducted otherwise if a command is not used. • I'm not aware of any 'buy' command, method, function, subroutine or instruction so use a thesaurus and find the closest word you can actually program. I don't expect the program to actually buy or snap anything. Other words like mail and fax are possible, but not recommended. • If you have to use a synonym, you are not allowed to use that command again • Encompassing multiple objects into one artifact does not count. For example, taking the command "name it" literally means you won't be able to name an array of bytes, but you can name a file. Creating an object that holds both a file and an array of bytes is not allowed. That would make this too easy to get the maximum amount of points. # Scoring • There are 16 commands with a total possible score of 190 points. • 10 points for executing a command on the specified 'it' of your choosing (160 total) • 2 points for executing each command consecutively that references your 'it' (30 total) • 5 points for executing a command on something other than your 'it' • -3 points for every command skipped. # Command List lyrics Buy it, use it, break it, fix it, Trash it, change it, mail - upgrade it, Charge it, point it, zoom it, press it, Snap it, work it, quick - erase it, Write it, cut it, paste it, save it, Load it, check it, quick - rewrite it, Plug it, play it, burn it, rip it, Drag and drop it, zip - unzip it, Lock it, fill it, call it, find it, View it, code it, jam - unlock it, Surf it, scroll it, pause it, click it, Cross it, crack it, switch - update it, Name it, rate it, tune it, print it, Scan it, send it, fax - rename it, Touch it, bring it, pay it, watch it, Turn it, leave it, start - format it. • This conversation has been moved to chat. Sep 17 '15 at 21:06 • I count way more than 16 commands here. There are 16 lines each with several commands on them. If we cound the hyphenated commands as two, there are 16 x 4 = 64 commands. Sep 22 '15 at 22:01 • @steveverrill A slight oversight. haha. I must've counted the lines knowing there were 4 commands on each line and didn't multiply the two together. Sep 23 '15 at 12:31 # Just Golf 2016 code-golfkolmogorov-complexity (Related: A Kingdom Hearts VGM challenge) Sandbox note: potential duplicate? Just Dance 2016 is coming out soon, and I know I'm definitely excited! However, let's take a quick trip back to 2009, when the original Just Dance was released. There are a lot of great songs, but I don't know who sung half of them! ## The Challenge Write a program that accepts a Just Dance song name from input and outputs the song's artist (as credited in-game.) Here is the list of all songs and artists from Just Dance 1: list pending ## Rules and Assumptions • You may assume that the song will always be valid. • The song's title and artist must be properly capitalized. • You may not read any external files - the song data must be hardcoded. • If a song is covered (which several have been for various reasons), the program should return the cover artist (as they are credited in the game.) ## Test Cases Input: Eye of the Tiger Output: Survivor Input: Fame Output: Irene Cara ## Bonuses • Each game has had one song everyone was really excited about. This year, it's Ievan Polkka by Hatsune Miku. You get a bonus of -50 points if you accept this song as valid input. • Just Dance is fun, but why should we stop there? If you additionally accept songs fron the rest of the main series (Just Dance 2, 3, Greatest Hits/Best Of, 4, 2014, and 2015, not including DLC and skipping over any duplicates), you get a whopping -2009 points. Here is the full list for those games: list pending • Note that this doesn't include Just Dance 2016 songs. • This can be combined with the other bonus to get a total of -2059 bytes. ## Meta Questions • Are the bonuses too big? (I'm mainly talking about the -2009 point bonus for including every song.) • Has anything been left out? • Is this enough of a challenge? • This looks like a dupe of codegolf.stackexchange.com/q/53678/194 . Sep 24 '15 at 20:24 • @PeterTaylor I would say it isn't, that one asks for input in the form of a game and boss and returns a song, mine asks for a song and returns an artist. That one also has different scoring rules, and mine requires all items to be implemented. Sep 25 '15 at 13:51 • They're both "golf this given map / dictionary / associative array". Why would the techniques used be any different? Sep 25 '15 at 15:22 • @PeterTaylor According to this meta post, the main qualification for duplicates is "Can answers from one question be copied over to the other with little or no modification and still be competitive?". I looked at the answers for the question you linked, and it doesn't seem like either would do very well if those techniques were used in this challenge. Sep 25 '15 at 15:35 • Would this be kolmogorov-complexity? Sep 26 '15 at 17:16 • @LegionMammal978 Yes. Sep 27 '15 at 14:48 # Literally just printing the source code Wait a second. We already have a contest where you print the source code. Right? Wrong. ## The challenge Print out the source code. Not to STDOUT, but to a physical printer. The rules: • You must write a complete program that prints out its own source code with a printer connected to the computer. • No STDIN (or input of any kind), STDOUT, or STDERR. • No standard loopholes (includes no file input). No using lp(r/d) or similar commands. • The printed code should be a reasonable size (between size 8 and 18) and a legible font (pretty much means no wingdings). • You may assume that the user doesn't cancel the process and answers affirmatively to any system print dialogs. • You can assume that the printer works, is ready, doesn't need new ink/paper, etc. • If the language doesn't support printing, it is ineligible. • This is so shortest code, in bytes, wins. • This is a trivial extension of the quine challenge. All you have to do is say you're running it on Unix/Linux and pipe the output to lpr. – user45941 Nov 1 '15 at 22:21 • This needs a much tighter spec on the hardware. E.g. I assume you would consider it cheating to post an ordinary quine and say "On this computer, all console output is also logged to a continuous print spool", but there are computers which are configured like that for audit reasons. Nov 2 '15 at 14:39 # Restricted "Hello, World!" The task is very simple, output Hello, World! to STDOUT. The thing that makes this different are the rules: • You need to provide a full functioning program, taking no input and outputting via STDOUT. • The program must not write anything to STDERR • The maximum amount of bytes you can use is 50 • The program may only contain printable ASCII characters. Programs using CP437 and other encoding systems are not allowed • If a programming language is already used, you cannot use this same language again. • You cannot use any character of the prohibited character list. This is the twist: ### Prohibited character list (PCL): The prohibited character list is a list full of characters, which cannot be used in the following programs. For example: If the list was: He\., you need to create a program, without the characters H, e, \ and .. These are not case-sensitive. If you succesfully manage to write a program that doesn't use any characters, you may add new one character to the prohibited character list. e.g. If the old PCL was He\., and you managed to write a program that doesn't use any of these characters, you may add a new character to this list. For example  (whitespace). The new PCL will be He \. (notice that the whitespace character is added). ### Posting Snippet: This might help you wit posting your submission: #[Language Name], N bytes [code] (explaination etc.) Added character: [char] New PCL: [list + new char]  In the beginning, the PCL is empty. The last person who managed to create a program without a new program made in 2 days, wins! I'm not really sure if it is flawed or not. If you have any suggestions or comments, feel free to post them below in the comment section :) • Already exists. Nov 22 '15 at 23:38 # What day of the week is Christmas? Christmas is coming quickly, which leads to the question, what day of the week is Christmas this year? But what day of the week is Christmas for any year? Write a program that can do this. This is code golf, so the shortest code wins! However, there is a major twist. No builtin functions to do this task is allowed! Bonuses: 1. If the program can handle B.C. years as negative numbers, then -25% 2. If the program prints "The first Christmas!" for an input of -4 (4 B.C. is assumed to be when Jesus Christ was born), then -30 bytes 3. If, for some reason, you really like builtins, +90%! So try NOT to use it! • The bonus for printing extra should be steeper, or no esolangs are going to go for it. Nov 29 '15 at 1:45 • @VoteToClose so more like 25% as well? Nov 29 '15 at 1:48 • No - I'd go static. Plus, this is really close to being a dupe... Nov 29 '15 at 1:51 • Near dupe of codegolf.stackexchange.com/questions/1003/… Nov 29 '15 at 1:52 • It's unspecified what format we should output in or what calendar we should use, and whether -4 should mean 4 BC or 5 BC. Nov 30 '15 at 5:57 • @ThomasKwa it should be obvious from the sentence that 4 B.C. is -4. Use the Gregorian calendar, output can be in MMDDYY Nov 30 '15 at 6:09 • How is MMDDYY a day of the week? Nov 30 '15 at 16:32 • @ThomasKwa sorry, it was pretty late when I wrote that so I mistakenly wrote MMDDYY. Just printing the day of the week is fine i.e. print "Sunday", "Monday", "Tuesday", etc. Nov 30 '15 at 19:57 # Golf A Wiki ## The Challenge Golf a wiki. A wiki, for the purposes of this contest, is defined as a website with: • Content editable by all • Easy CamelCase (defined as a word with two capitals) linking • Different pages or articles that are the targets of the links Your wiki can be a self-contained HTML file (e.g. TiddlyWiki), or a cgi-bin script (e.g. SigWik). ## Scoring Your score is the size of your program in bytes, divided by the number of extra features implemented plus one. The possible extra features are: • Page history • Syntax for "nowiki", that is, something like <\noscript> in HTML that makes the text inside it not be wiki syntax. • A page list • A find page facility • Usernames and passwords (with registering) • Security levels (requires usernames and passwords, or possibly IPs?) • Delete pages • Change page titles • Redirects • Random page • Non-HTML formatting that is not just links [Should I remove this? I doubt it will be done.] Lowest score wins, as this is code golf. # DISCLAIMER ANSWERS WILL PROBABLY CONTAIN MAJOR SECURITY FLAWS. ONLY USE ON PRIVATE PORTS, UNLESS YOU WANT YOUR COMPUTER AND VERY POSSIBLY YOUR WHOLE NETWORK TO GET DESTROYED (FIGURATIVELY). [Is this too forceful?] • I would vote to close this as too broad. Among the problems I see: 1. The two given examples don't seem to be the same thing as each other 2. The complete lack of constraints mean that I could just automatically make every word a link. (This could be fixed by specifying one link syntax: for golfing I quite like the UseModWiki use of CamelCase for links). 3. I think I can get the "text formatting" feature for free by not escaping HTML characters. 4. Needs a big warning "Answers will likely contain major security flaws and should not be used on ports which are publicly visible" Dec 30 '15 at 10:49 • Ok, thanks, I'll edit when I have time today. Dec 30 '15 at 21:27 ## Progress 100% I am building a download manager and I need to show a progress of all my files been downloaded. For that I created an event mechanism that reports on the progress of each individual file. It sends me the information on how many bytes B have been downloaded of file T total. Please help me show the average progress of all the files. ## Input Integer C between 1 to 100, followed by new line, followed by C progresses separated by new line. Each progress is constructed of two numbers with the maximum size of 64 bits: B T, separated by space. Input options The input is a String available from the following options • file • stdin • method parameter ## Output Floating number between 0 to 1, the average of all the progresses. It must be displayed to 11 decimal places, floored. ## Criterial Shortest code wins ## Example Input file: 3 5 10 1024 1024 20 100  Output 0.56666666666  Explanation ((5/10) + (1024/1024) + (20/100)) / 3 = 17/30  ## Example2 Input file: 1 2 10  Output 0.2  ## Example3 2 Long.MAX_VALUE Long.MAX_VALUE 5 10  Explanation In this example Long.MAX_VALUE represent the maximum 64 bit value, so if you use 64 bit value for storing the sum of the averages it will not work in this case. Output 0.66666666666  • 1. It's not clear from your specification how the result should be computed. The "total progress" implies to me that I should figure out how many bytes have been downloaded of the total, i.e. sum(B)/sum(T). However, your first example suggests, that we should actually compute the arithmetic mean/average of the individual progresses. If so, please state this clearly. 2. By requiring 11 digits of accuracy, you require 64-bit floats (double precision), because 32-bit floats only have 7.something decimal digits. Is this intentional? (seeing your input is only 32 bits) Apr 1 '15 at 20:39 • @MartinBüttner how about now? I do want the high precision Apr 1 '15 at 21:24 • My first point still stands. It's not clear from the specification how the result should be computed. Apr 1 '15 at 21:27 • @MartinBüttner I expect you to process all the progresses and find the average one, not sure how to say it right. Apr 1 '15 at 21:28 • Just like that, but as far as I can see your challenge currently doesn't mention "average" or "arithmetic mean" anywhere. Apr 1 '15 at 21:32 • @MartinBüttner Anything else? Apr 1 '15 at 21:40 • Why did you remove it again? And what's the purpose of the hint? Apr 1 '15 at 21:43 • @MartinBüttner sorry had 2 windows opened. The hint helps you to understand that you cannot store the sum of all the progresses in 64 bit value. Apr 1 '15 at 21:45 • What does "up to 11 digits of accuracy mean"? That I can supply only 3 digits, but I may not supply 12? And what counts as a "digit of accuracy", anyway: are you talking decimal places or significant figures? And if significant figures, what is the correct output if the average progress is exactly 0? Apr 1 '15 at 22:37 • @PeterTaylor I want an 11 digits after the dot of accuracy in the output. So 3/10 will produce 0.33333333333 and 0/10 will produce 0. Maybe you can suggest a better way of writing it down. Apr 1 '15 at 22:40 • I've edited in some changes. I would suggest also deleting the hint and replacing it with a test case. It would also be good to describe a test case (it will probably be too long to post) which demonstrates that it's not sufficient to use IEEE754 double-precision. Apr 2 '15 at 7:35 • @PeterTaylor is it ready now? Apr 2 '15 at 14:09 • It would also be good to describe a test case (it will probably be too long to post) which demonstrates that it's not sufficient to use IEEE754 double-precision. Apr 2 '15 at 19:28 • @PeterTaylor I don't understand what you are saying, can you please explain it a little bit more Apr 2 '15 at 20:15 • Since you're requiring programs to support averaging 2^31 numbers and you want output to a precision of about 35 bits, a naïve solution with 64-bit floating point will be incorrect, but that might not be obvious to everyone who would attempt an answer. Apr 2 '15 at 20:23 Write a polyglot (a program that works on several languages) that produces the // this is a comment output. ## Example (JS + Plain PHP + Plain HTML) (74 / 3 = 24.66 points) // this is a comment<?php ob_start();?><!-- alert("// this is a comment");  ## Another Example (CoffeeScript + CJam + brainfuck) () e###-[----->+<]>----..+[--->++<]>.---[->++++<]>.------------.+.++++++++++.+[---->+<]>+++.-[--->++<]>-.++++++++++.+[---->+<]>+++.[->+++<]>+.-[->+++ <]>.+[->+++<]>.++++++++++++.--..--------.+++++++++.++++++. "// this is a comment" e### alert "// this is a comment"  ## Scoring Your score will be code byte length / num langs The smallest score wins! • Is there anything that makes this significantly different than polyglot Hello World? Feb 1 '16 at 14:03 • @Geobits this is more easy, really Feb 1 '16 at 14:37 # Linear Time Sorting It was another slow day at Initech Inc. when a feature request came in: New Feature: Ability to sort by cash value in the transaction form. But make it a fast one!  Well it looks simple.. but what do the requester mean by fast one? Let's call Jim, from sales he probably knows what's going on. Jim: Well you know , our Business Inc. contact is very passionate about programming and computer science! In fact he had this idea that we should do sorting in how that was called.. linear time? You: Well you know that's impossible? Jim: But it was already approved by their cto and all! You need to do something  You and Jim came up with a plan.. nobody will notice if that big of a list isn't sorted enough, right? # Your task Your task is to write a linear time sorting program. It will be scored on accuracy of the sort as compared to list sorted by regular sorting algorithm but it must work on O(N) time in the worst case, where N is length of the input. Input will be in the form of list of string-double tuples, e.g: [("aaaa",2.0) , ("aaba",1.0)]  The program should sort on the number value of the tuple, i.e. in the above case the order should be reversed. There may be multiple inputs with the same double values, but no string value is repeated. In the event that two inputs have the same integer value the perfect solution is to keep the order as it is. The double value may be any floating-point value that fits in 8 byte double precision variable. NaNs should be placed at the end of the list. The score is calculated as number of "bubble sort operations" (switch an element with the next/previous element) needed to achieve perfect output from the output of your algorithm. # Sandbox Worries Well I don't know how clear my explanation of challenge was and if it is interesting to the PPCG crowd. Obviously there is a need for testing program and test cases. • How big will the test cases be? If you pick a fixed size, the response will be "n passes of bubble sort where n is the size of the largest test". Bam, linear with perfect score. Apr 11 '16 at 10:12 • @JanDvorak I rephrased the scoring sentence to more reflect what I meant. In that case the score wouldn't be perfect as after just n switches the list wouldn't be the most ordered. EDIT: I think I understood it now. Well I think you can somehow exclude answers like that with some caveats in the rules, like "Your algorithm cannot make any assumtions about length of the input" Apr 11 '16 at 10:17 • I don't make any assumptions. It sorts every array up until the largest test case correctly and all other arrays partially. Apr 11 '16 at 10:28 • An algorithm that fares better than n-pass bubble sort is to do a level-n mergesort. If the length exceeds 2^n, sort each [k::len/2^n] subarray separately. Apr 11 '16 at 10:32 • But then you're making assumptions based on the size of the test cases - if somehow the test cases were changed (but still fitting the rules) to test cases which are much longer (for example you prepared for max 10 element list and you get 100000 element list) your program isn't linear. Apr 11 '16 at 10:41 • The problem with a spec is that it cannot change once you've posted the challenge, and you can't define "making assumptions based on the size of the test cases". You can't even ban all magic numbers - I can simply use functions merge1 .. merge20 Apr 11 '16 at 10:47 • It isn't the spec - the way the test cases used to grade the result are constructed is described but do I have to post the test cases (but those used to score) themselves? Apr 11 '16 at 10:50 • You need to define the test cases, and you can't change them based on the answers (if only because updating the score of every answer would be a nuisance). Maybe you could ask for asymptotic behavior, but that can be surprisingly hard to measure. Apr 11 '16 at 10:53 • Hidden test cases are a problem as well, because then we can't test the submissions after you're gone. Apr 11 '16 at 10:55 • The idea was to pregenerate some test cases (undisclosed) and some test cases that are disclosed (for testing purposes during the coding) and then do a cutoff time for the challenge where all the solutions are tested against the undisclosed challenges. Also obviously after the cutoff time the test cases would be disclosed. Apr 11 '16 at 10:56 • 1. Most real-life data types can be sorted in linear time, so the premise of the question seems badly flawed. 2. "Input will be in the form of list of string-double tuples ... There may be multiple inputs with the same integer values" Huh? Where do the integer values come from? 3. "The double value may be any floating-point value" Where do NaNs sort? Apr 11 '16 at 16:00 • 1. The idea is that the data may be the worst case for any algorithm that can achieve linear sorting time 2. It was a typo 3. At the end - I will put it into the question Apr 11 '16 at 18:36 • Why does the input being worst case make any difference? The solution will still be perfect, so you'll need a tie-breaker to separate every single answer. Apr 11 '16 at 21:27 # Make a quine without using string literals popularity-contest A quine is a computer program that prints out it's own source code to stdout. Your task is to make one that doesn't use string literals. You cannot: • Have any empty program • Read your source code directly or indirectly (i.e. form a file) • Use error messages to print out the source code • Rely on language features to print out the source • Relying on a REPL environment A string literal is a: • String type (obvious) • Number used to store the character (sorry BF!) • Other predefined constant You are encouraged to compute your own source code. • This hits two of the "things to avoid when writing challenges": do X without Y and popcons. (I assume it's an attempt to finesse a third: generalised quines). It also has some fairly bad phrasing: what language can print anything without using "language features"? In what way does BF use literals? How many languages can compute anything without using at least one constant? Apr 12 '16 at 7:27 ## Cops and robbers : Programmers/Hackers • This challenge is quite different from my previous challenges. This challenge is an endless competition between robbers and cops, which are respectively hackers and programmers. One of them will ever win!!! • This will evolve to code de/obfuscating when it gets to the higher stages: a skillful programmer who is struggling to save his program from a sourcecode-mangling attempted by a cunning "robber" who tries to impose his existence by patching his name instead of the name of the "programmer" in the output console without changing anything else in the code. The story begins this way: • Programmer is at the point of executing his recently made C code, so he included this trivial line to show off: C (1)  printf("[Programmer's username]")  After executing this program programmer saw this on the screen: [Robber's username]  which indicates the presence of some evil code at the compiler level that compromises his code, which follows: Matlab (2)/parser  a=findstr(code,'printf(''[Programmer's username]'')'); if a code(a:20)='printf(''[Robber's username]'')';end  The programmer cannot modify the counter-program in the compiler, so he must rather change the program content to escape the twiddling: PHP (3) $a='[programmer's username]';echo $a;  The score is now 3, which is the number of steps from the beginning. The current user would win only if the hacker did not figure out something like: PHP/Regex(pcre flavor) (4) $code=ereg_replace("(\$\w)\='programmer';(.*?);echo\s\1","\1\='robber';\2;echo\s\1",$code)


Since the solution above does not satisfy the rules (see the bottom of this question), the score stays unchanged, and the programmer can make a counter example, and take out the score from last submitter with a penalty on his score equivalent of how much he earned in the earlier level, where the counter example can be something as:

PHP (4)

      $a='programmer';$b=$a;$a='unrelated';echo $a;  Or he can adjust his program in higher scale to escape all the regex-trapping in a superior range, So the cycle goes on until no post can be added and the last submitter before the end of June is declared a potential winner meanwhile. The hacker can also fix his regex and regain his score, so the recent scoring will be abrogated from programmer. Perl/dynamic-regex (4) local @a=(''); sub check{ if (grep {$_ eq @_[1]} @a)
{push @a,@_[0]; }
elsif  (grep {$_ eq @_[0]} @a) { my @del_indexes = grep { @a[$_] eq @_[0] } 0..$#a; foreach$item (@del_indexes) {
splice (@a,$item,1); } } return 1; } sub actor{ if (grep {$_ eq @_[0]} @a)
{return "print robber";}
else
{return "print ".@_[0];}
}

sub initiate{
push(@a,@_[0]);
return 1;
}

$code =~ s/(((\w+)\="programmer"(??{initiate($3);}))|(print\s(\w+))|((\w+)\=(\w+)(?{check(($7),($8));})(?1)))/print($2);actor($5)/pegmx;


As you can see this Perl program prints b in the first case because the variable b is compromised after the first assignment, but in the second case the regex modifies the output because d receives the target-string transitively. Let's just stop here and not mess the fun (of course, if there will be some).

## Scoring and rules

How is the score counted ?

• Any hacker/programmer is scored for his code as the actual level L the game is on.
• A partial dynamic regex within the core of the program is scored L + (2^L)/log(length of program + length of characters which do not belong to the regex)), where the log is base 2. For the second example of level (4) the length of the compacted program is 480, and the length of regex is 136, so the score is 4+2^4/log2(480+480-136) ~= 4+16/9.6
• A fully functional regex as in the first example level (4) is scored L + (2^L)/log(length of regex), where the log is base 2, in that case S = 4 + 2^4 / log(91) ~= 4+16/6.5
• Scores are added progressively to submitters, and when a level is surpassed with no regex, it is still open for scores, while the actual winner remains unchanged.
• A penalty on a certain-leveled score when the regex/parser is revealed out of rules and the game is regressed to this stage until the issue is fixed, rules are cited below:

Rules:

• The main rule: the hacker-program must compromise an output to the console, which is the username of the programmer. Any other behavior is unaccepted simply because a string variable of [programmer's username] can be used in other order rather than printing, a counter-example is easy, converting the string to integer then use it for arithmetic calculations that harms the main program once intentionally modified.
• Also one of the following factors declared by any counter-example bans the targeted flawed regex/parser as non rule-complying:
• The regex/parser prints anything other than a chosen string preferably set as the username of the robber.
• The regex/parser generates a program which does not compile.
• The regex/parser does not print anything, or compromises a segment of code that is needed for tasks other than printing .
• The variable which stores the program is named code by default, also you may assume that is one-liner, and any non-significant spaces are omitted, and that it is fully working by default.
• The regex/parser deals with one variant of one code proportion in a comprehensive way, i.e. if a print function is used, that encompasses all printing functions in all languages puts,disp,..etc. Also, code separators can be unified to one characterL either , or ; or a significant space needlessly of enumerating all keywords/syntaxes, this is not a contest about a working code in a specific programming language.
• To prevent endless program/regex loops let's just not making a jokey sequence as a='programmer';print a / /(\w)\='programmer';print\s\1/ / a='programmer';b=a;print b / /(\w)\='programmer';(\w)\=\1;print\s\2/ because the first person who makes a regex/parser which palliates to a same replicated idea will take out all attributed scores to this idea from their owners, so any anaphoric sequences like this in addition that they are set to same level, they are unneeded.
• Any language that uses pointers/addresses/classes like C++ are welcome, as long as they help to evade the hacker.
• Please, for the love of god, spell things correctly. In the first bit alone I spotted a ton of spelling mistakes without even looking for them. Also, that whole first list is... basically impossible to understand, at least for me. Maybe use full sentences?
– Nic
May 10 '16 at 21:29
• Have you seen our cops-and-robbers challenges? It sounds like that is what you are trying to do here. That said, there are a couple of problems with the spec: Defining what parts of the language counts as a "partial regex" or "full regex" is really tough, especially when we get into esoteric languages. May 10 '16 at 21:36
• Could you add a short summary to the post? I don't understand what the actual task here is. Is this a cops-and-robbers or answer-chaining challenge, or something entirely different? May 10 '16 at 21:36
• i will see what cops and robbers is May 10 '16 at 21:39
• @NathanMerrill this is not a code golf so i dont see the point of introducing esolangs here May 10 '16 at 22:28
• @Agawa001 Esoteric languages are still useful outside of golfing. You can use them to make it tough for regexes to match. May 10 '16 at 23:06
• The introduction is very long and after reading it I have no idea what the task is. I would have to vote to close this as "Unclear what you're asking" in its current state. May 11 '16 at 7:45
• So what's the core mechanic? Is this an answer-chaining question where answers must alternate programmer and hacker? But if the programmer can change language at will, how can the hacker hope to win? May 12 '16 at 12:06
• @PeterTaylor yes it is answer chaining but the last submitter can post two consecutive answers and be the robber and cop themselves, the programmer change his code, hacker changes his regex taken consideration of all last regex/parsers. May 12 '16 at 16:13
• I have no idea what this challenge is supposed to be. The very little explanation of the concept is muddled by spelling and grammar issues. Please, learn English spelling and grammar before trying to write a challenge.
– user45941
May 13 '16 at 5:18
• @PeterTaylor refer at the 4th rule, procedures which accomplishes a specific task in different languages are dealt as one thing, this is not a challenge about checking language-syntaxes, when a programmer changes language, consider all previous regex/parsers changed to trap same functionnalities of previous code on the new language. May 28 '16 at 11:37

## Challenge

Write a program that takes an numerical input n and outputs the nth number that is not a perfect square.

## Rules

This is , so least bytes wins.

• What's the maximum expected input? Does it expect 0? How do we handle 0? Is there a requirement on the efficiency for large inputs? Also give some example inputs and outputs. Jun 17 '16 at 20:19
• Here's some test cases I just generated: 1->2,2->3,3->5,4->6,5->7,6->8,7->10,8->11,9->12,10->13,11->14,12->15,13->17,14->18,15->19,16->20,17->21,18->22,19->23,20->24,21->26,22->27,23->28,24->29,25->30,26->31,27->32,28->33,29->34,30->35,31->37,32->38,33->39,34->40,35->41,36->42,37->43,38->44,39->45,40->46,41->47,42->48,43->50,44->51,45->52,46->53,47->54,48->55,49->56,50->57,51->58,52->59,53->60,54->61,55->62,56->63,57->65,58->66,59->67,60->68,61->69,62->70,63->71,64->72,65->73,66->74,67->75,68->76,69->77,70->78,71->79,72->80 Is this the function you expect? Jun 17 '16 at 20:41
• Yes, yes it is. Jun 17 '16 at 20:42
• Can you address my other questions please? Namely, the largest expected input and how to handle input of 0. Jun 17 '16 at 20:43

# Generate all variations of a string with every combination of upper and lower case for each vowel but leaving consonants and order of letters unchanged.

This is a simplified analog of a problem I've thought about a few times over the years based around variant spellings in different spoken languages.

Input is a text string. Output is an array of all variations of the text string.

A "variation" means the same letters in the same order but for each vowel letter in the string we generate a version of that string with the vowel in uppercase and the vowel in lowercase.

No variation should be included more than once. No legal variation may be omitted.

# Example

## Input

codegolf

## Output

• codegolf
• codegOlf
• codEgolf
• codEgOlf
• cOdegolf
• cOdegOlf
• cOdEgolf
• cOdEgOlf

The winner shall be the most elegant as voted by the community.

"Elegant" includes that the algorithm should be optimal in terms of Big O notation, should be concise, should be idiomatic making good use of available features of the implementation language.

Length of code characters or bytes is not relevant.

Programming language is open.

• "most elegant as voted by the community." I doubt many answers to such a challenge will be deemed elegant. Jun 23 '16 at 13:01
• Really? Anything to suggest instead? Just "best" is usually no good for Stack Exchange... Jun 23 '16 at 13:22
• Code golf version of this challenge: codegolf.stackexchange.com/q/80995/8478. That said, I don't think "most elegant" makes a good popularity contest and is very likely to be downvoted and closed almost instantly. If you're looking for elegant solutions, this might not be the right community in the first place though. You could write your own solution and post it on Code Revew to ask for improvements. We generally require objective winning criteria for our challenges, and popularity contests are in a weird place where you need to come up with something really good for it to be accepted. Jun 23 '16 at 13:30
• Hmm well OK whatever. Jun 24 '16 at 11:55

# Oh noes! A site redesign is eating my privileges!

PPCG is graduating and will soon receive a new design. Unfortunately for everbody except some people, the new design will also mean losing privileges due to higher reputation requirements.

Now, losing some privileges is a small sacrifice for the Magnificent Glorious Site Redesign®©™, but… How much do we stand do lose?

## The challenge

Your program / function receives a reputation level (e.g. 535). Output the privileges that are currently available to it, but will not be available after the redesign.

### Output

Output can be either an array or a string that's separated by a delimiter. The delimiter may not be any of A-Za-z<space>. Multi-character delimiters may end in a space, though.

If there are no matches, your program should output either an empty array or a falsy value.

### Examples

Input
25000

Output
[]

Input
24999

Output
["access to site analytics"]

Input
2000

Output
["access to moderator tools","approve tag wiki edits","cast close and reopen votes","create tag synonyms"]

Input
535

Output
["cast close and reopen votes"]

Input
350

Output
["access review queues"]

Input
5

Output
[]

Input
4

Output
["participate in meta"]


Deliberately ignoring the facts in the last example.

### Available privileges

For convenience, here is a JSON array with available privileges and the required reputation before / after:

[[5000,25000,"access to site analytics"],[4000,20000,"trusted user"],[3500,15000,"protect questions"],[2000,10000,"access to moderator tools"],[1500,5000,"approve tag wiki edits"],[500,3000,"cast close and reopen votes"],[1250,2500,"create tag synonyms"],[1000,2000,"edit questions and answers"],[750,1000,"established user"],[1000,1000,"create gallery chat rooms"],[350,500,"access review queues"],[150,300,"create tags"],[250,250,"view close votes"],[125,125,"vote down"],[100,100,"edit community wiki"],[100,100,"create chat rooms"],[75,75,"set bounties"],[50,50,"comment everywhere"],[20,20,"talk in chat"],[15,15,"flag posts"],[15,15,"vote up"],[10,10,"remove new user restrictions"],[10,10,"create wiki posts"],[1,5,"participate in meta"],[1,1,"create posts"]]


At index 0 is the reputation before, at index 1 is the reputation after. (The privilege reduce ads (200 reputation) is not available to beta sites and therefore not included in this list.)

Standard I/O and loophole rules apply.

• Related. It's borderline whether this adds enough to not count as a duplicate: I would vote that it does, but I wouldn't cast my supervote. Jul 12 '16 at 16:21
• @PeterTaylor I'm thinking of changing the challenge to allow submissions to download the privilege page. I guess that would make it distinct enough. Jul 13 '16 at 10:53
• Turns it into a hybrid parse-HTML and merge data sources question. Yes, I think that's novel. You should make it very clear that the answers should keep working after the contents of the privilege page are updated to show the new rep levels; and possibly you should take a backup copy of the page in case of future addition of new privileges. Jul 13 '16 at 11:01

Plot Partial Node Network

I have a 440*3 matrix that looks like:

1   144 Title1
1   152 Title2
1   135 Title3
2   3 Title4
2   12 Title5
2   107 Title6
2   31 Title7
3   4 Title8
3   147 Title9
3   0 Title10
4   end Title11
4   0 Title12
4   0 Title13
5   6 Title14
5   7 Title15
5   10 Title16
5   9 Title17


The left column are the starting points eg in the app all the 1's on the left would be on the same page. They lead to three choices, pages 144,152,135. These pages can each then lead to another page, and so on until the middle column says 'end'.

challenge Each number has an associated title in column three. I would like to have a function whereby if you input a given title it will plot all the possible starting points and their associated paths that will lead there. This should be a lot smaller and therefore graph friendly.

Example e.g.

44  234  tes
186  187  Frac
187  154  Low
154  end  Coll
23   52   Med
52   11   Lip
11   42   AAA
42   154   BBB
154   end  Coll


EDIT - I added to the example. In the winning entry these new nodes will not be plotted as they do not lead to Coll.

I made this example to show how column 1 leads to a value in column 2 which then refers to a value in column 1 until you reach the end. Different starting points can ultimately lead to different length paths to same destination. so this would look sometigng like:

So here, I wanted to see how you could go from all start points to 'Coll'

Input A data.frame like that illustrated (with not relevant rows included) and a given title

Rules -any language is fine as long as it will easy work with tab separated data laid out as shown

Output A graph like the one included for a given title

Win Criteria Shortest Runtime to make a png with graph

• A question should have one challenge, not two. And a challenge should ideally have one goal, not two; and should certainly have a clear description not only of the input but also of the output. Jul 13 '16 at 16:14
• Hi Peter, thanks for this. I've edited accordingly Jul 13 '16 at 16:16
• Jul 13 '16 at 22:58
• they're similar but not the same. they dont solve the problem of just plotting the rows that lead to Coll. Jul 14 '16 at 7:30
• i edited example to clarify this Peter :) Jul 14 '16 at 7:45
• I do like this question, but I currently do not support it as a question, due to it being unclear as to exactly what the png can and can not look like. I do support graphical output questions. Jul 15 '16 at 1:47

# The Library Problem

Bob has a very annoying problem. His boss told him to write a cat program that redirects the standard input to the standard output. But he recently installed a virus on his computer which deleted every libraries on it.

Now he really need to create this program without using any library (even the language standard library). It need to run at least on one operating system with one architecture.

# Challenge

Write a program or that redirects the standard input to the standard output without using any library or external program/command to run to help Bob. You can use system calls and interrupts for example, but your program must not run in ring 0 mode (most operating systems like Microsoft Windows or GNU/Linux have kernels which prevent programs from doing anything, but MS-DOS for example let programs do everything).

• Input: anything (text, binary)
• Output: exactly the same as the input

This is , so shortest answer in bytes wins!

# Example Input and Output

First:

• Input: Hello, world!
• Output: Hello, world!

Second:

• Input: ...
• Output: ...
• That's just this challenge isn't it? Jul 21 '16 at 15:26
• @MartinEnder This challenge is about doing a cat program without using any library or external command/program even the standard library built with the language.
– user54187
Jul 21 '16 at 15:30
• So everything would need to be written in assembly or equivalent? Jul 21 '16 at 15:34
• @TimmyD Yes for example, but I think there are other lower-level languages which allow this.
– user54187
Jul 21 '16 at 15:34
• In that case it just seems like the same challenge limited to a small set of languages? In that case it would probably still be considered a duplicate and the usual course of action is to offer a bounty for the language you want to see a solution in. Jul 21 '16 at 15:38
• @MartinEnder You need a lower-level language but it doesn't mean that every program made using a lower-level language works with this challenge. See this answer for example which uses a function from the standard library codegolf.stackexchange.com/a/62309/54187.
– user54187
Jul 21 '16 at 15:46

# Alphabet Circle

This post got very negative feedback, so it's apparent that it needs tweaking in the sandbox before I attempt to repost it on PCG

With all the new alphabet xxx challenges, I've decided I'll give my own challenge.

Input

An Integer, (or your languages equivalent) r, such that 0 < r ≤ 26. (you don't need to validate this)

Output

An alphabet circle. Must meet the following criteria:

• Smoothly interpolated from A at the center and Z at the edge.
• Each point in the circle is the distance from the center offset so that 0 = A, 1 = B, 2 = C etc...
• Be printed to STDOUT

Examples

r=26

r=15

Boilerplate

Anonymous classes and functions are fine. General Code Golf rules apply. Shortest code in bytes wins!Except Jelly

• Please remove the Except Jelly part... Aug 3 '16 at 11:31
• @TùxCräftîñg no Aug 3 '16 at 11:32
• Disallowing language are a thing to avoid when writing challenges Aug 3 '16 at 11:35
• It's triple super scripted, it's a joke. I'm not removing it. Get a sense of humour! Aug 3 '16 at 11:49
• Since you mention negative feedback, my negative feedback would be that a glut of recent challenges on theme X (in this case alphabet layout) is a strong reason to avoid more challenges on theme X for a while, not to add to the pile. Variety is good. If I were you I'd hold this challenge for a month. Moving onto positive feedback, the spec needs to define the desired layout more clearly. I can't work out what the precise criterion is for which letter to place in each space. Aug 3 '16 at 14:51
• If a position is not an integer distance from the centre, should the distance be truncated, rounded up/down or something else? Aug 6 '16 at 12:11
• Could you specify whether leading/trailing spaces and newlines are permitted/required? Does the circle need to be framed in a square of matching size, or can it always be in a square of a fixed maximum size? Aug 6 '16 at 12:15
• I think this would work best as a kolmogorov-complexity just for the size 26 pattern. That'd avoid any issues with defining how to interpolate the circles (or, indeed, defining the pattern generally, as it would be defined via stating the intended output).
– user62131
Nov 24 '16 at 5:24

# 2 Pass Hello world

You've heard about this fancy new programming language, but you're not sure you understand it perfectly. So you want to go over a new "Hello world" tutorial again.

How boring!

Instead you have a good idea, using your knowledge of the first programming language to create a "Hello world" program in the second programming language.

Exemple:

console.log('print "Hello world"');


Evaluated in javascript output:

print "Hello world"


Which, evaluated in python 2.X output:

"Hello world"


Nice, but, can it be shorter?

• We have a tag for multi-language challenges, polyglot. May 4 '16 at 14:06
• Pyth: \H (Guess what the second language is) May 4 '16 at 14:08
• Maybe add a scoring mechanism by how many languages it works in? e.g. console.log('print("puts\'Hello, World!\'")') would score len(submission)/num_languages_it_works_in? May 4 '16 at 14:09
• Then the submission above would score 0. May 4 '16 at 14:09
• (To OP) Maybe you would need to add some more rules May 4 '16 at 14:11
• @KennyLau no? 2/2 = 1 May 4 '16 at 14:11
• @EᴀsᴛᴇʀʟʏIʀᴋ It can be fed into itself for one more pass... May 4 '16 at 14:12
• I didn't want to add any recursive mechanism, because the end goal should be to display "Hello world" but a more than 2 language is a great idea. May 4 '16 at 14:15
• I don't see how you will be able to come up with a good scoring system for this. Using two esolangs / two times the same esolang will result in 1/2 bytes answers right away. May 4 '16 at 14:16
• @KennyLau, what rules do you generally add to a incomplete challenge? we thought adding a time/memory limit for the execution, but seems irrelevant... May 4 '16 at 14:17
• This is really closely related to several other challenges we've had on the site, such as this one and this one. You'll need to be very careful to not make it a duplicate. May 4 '16 at 14:22
• Also this one, which is practically a duplicate, just with numbers instead of "Hello, world." May 4 '16 at 14:26
• Yeah, I haven't seen all this, I guess I'll start searching for another idea instead ;) May 4 '16 at 14:29
• Also, welcome to PPCG! (I forgot to mention that earlier). Hope you enjoy yourself here! May 4 '16 at 14:36

# Return True to Win - Counter javascriptcode-golf

Original credit goes to this site, which you should all check out

Write the shortest javascript code to pass as parameter f to function counter such that it returns true:

function counter(f) {
var a = f(), b = f();
return a() == 1 && a() == 2 && a() == 3
&& b() == 1 && b() == 2;
}


I'm considering also making this a series with all the rest of the challenges on the site, where each one gets harder

• Given the lack of a terms of use page on the site, the code on that site is copyrighted, with no provisions for reproduction. This is copyright violation.
– user45941
Aug 9 '16 at 6:00
• In addition to Mego's note regarding copyright, language-specific challenges are not typically well-received by the community. Aug 9 '16 at 18:18

# Nasty Nasty Bugs

Help the programmer provide detailed instructions to the team on how to deal with bug fixes.
The team's goto instructions for dealing with bugs goes like this.

For the twelfth bug of Christmas, my team leader said to me

Tell them it's a feature
Say it's not supported
Change the documentation
Blame it on the hardware
Find a way around it
Reinstall the software
Run with the debugger
Try to reproduce it
Ask them how they did it and
See if they can do it again.


The indentation must comply with the teams coding standards, so it may either be tabs or four spaces (since the team's editors expand tabs to spaces anyway). The team lead doesn't mind a leading or trailing newline, but there is no tolerance for the dreaded standard loopholes. Also the office is a bit cramped so the code needs to be as small as possible. These lyrics are moderately adapted from http://www.manbottle.com/humor/twelve_bugs_of_christmas

• What is the actual challenge? A kolmogorov-complexity to reproduce the quoted text verbatim? Aug 8 '16 at 21:41
• whoops should have tagged it as such @PeterTaylor Aug 8 '16 at 21:42
• There doesn't seem to be much of a pattern here. What does this add over other kgc questions? (And why isn't it a dupe of the Rickroll challenge?) Aug 9 '16 at 20:23
• @FryAmTheEggman I could put all 12 verses of the 12 bugs of christmas in. But then it could be a dupe of the 12 days of christmas challenge Aug 9 '16 at 20:24

# Crab Canon

A crab canon is a piece of music where the same tune is played backwards and forwards at the same time, and it somehow sounds nice. The most famous example is this one by Bach. In Godel, Escher, Bach, Douglas Hofstadter wrote a crab canon in dialog form, in which the characters of Achilles and the Tortoise alternate lines, with one set of lines being the same as the other set except backwards. Somehow, it makes sense.

The challenge is to write a program inspired by this art form. The only requirement is that there has to be some sort of reversal of the source code involved. For example, you could make a program that:

• Prints its own source code, but backwards
• Does the same thing when reversed
• Both of the above at the same time
• Or make up something creative and wow the voters!

The reversal can happen on pretty much whatever level you want: lines of code, characters, characters within lines, or whatever makes sense for your language. The Hofstadter Crab Canon has some small changes between the two sets of lines for the sake of coherence, you can do something similar if you feel it is necessary.

This is a popularity contest, the answer with the most votes wins.

• This is without a doubt too broad. See codegolf.stackexchange.com/tags/popularity-contest/info Aug 16 '16 at 7:10
• @PeterTaylor FYI there's something wrong with that link's formatting Aug 16 '16 at 18:07
• There isn't any formatting. I just pasted the link directly. And it works for me. Aug 16 '16 at 19:11
• @PeterTaylor hmm, seems to have fixed itself... Aug 16 '16 at 19:12

## Petals around the Roses

Given 5 numbers from 1 to 6, calculate the number of Roses, Petals and Roots. Try guessing the formulas yourself by visiting http://jetpackshark.com/RPS before reading anybody's answers. (The dice-like display is significant.)

This is , so the shortest program wins.

• If you're looking for a "solve-the-puzzle" challenge, the site for that is Puzzling. If you want it to be a code-golf, then please include a formula for how the roses, petals, and roots are calculated. Aug 16 '16 at 13:06
• Or at the very list a definition of roses, petals, and roots in this context. At present this question makes no more sense than the output of a Markov text generation process. Aug 16 '16 at 13:44

## Write a Brainfuck interpreter in Brainfuck

Since Brainfuck is known to be turing-complete, it is possible to write a Brainfuck interpreter in Brainfuck. This is what you're supposed to do.

You will get the input from the standard input and output to the standard output. This is a programming-puzzle, so the length is not top priority, however if there are multiple solutions, the shortest one wins!

• BF interpreter (non language specific) challenge has already been done, and language exclusive challenges generally aren't good Aug 19 '16 at 1:45

# Iпtгodцctioп

Iп tиe Iпteгпets, people sometimes liкe to stчlize tиeiг posts дs if tиeч щeгe щгitteп iп д diffeгeпt scгipt. Tидпкs to tиe пotoгietч of Soviet Яцssiд, tиe Cчгчlic scгipt seems to бe pдгticцlдгlч fдvoгed.

Бцt щидt cдп д пext-dooг tгoll do if tиeч'гe пot д pгogгдmmeг? Mдпцдllч гeplдciпg eдcи дпd eveгч letteг cдп бe qцite tedioцs...

# Cидlleпge

Чoц дгe to щгite д pгogгдm tидt щill дccept дп дгбitгдгilч loпg iпpцt of Lдtiп cидгдcteгs дпd sцбstitцte some letteгs щitи similдгlч looкiпg Cчгчlics cидгдcteгs. Tиe oцtpцt sиoцld бe ideпticдl to tиe oцtpцt pгodцced бч tиe folloщiпg цпgolfed C# scгipt:

цsiпg Sчstem;
цsiпg Sчstem.Collectioпs.Geпeгic;
цsiпg Sчstem.Liпq;

pцбlic clдss Test
{
pцбlic stдtic void Mдiп()
{
Dictioпдгч<cидг, cидг> tгдпs = пeщ Dictioпдгч<cидг, cидг>{
{'A', 'д'},
{'a', 'д'},
{'B', 'Б'},
{'b', 'б'},
{'N', 'И'},
{'b', 'и'},
{'K', 'К'},
{'k', 'к'},
{'N', 'П'},
{'n', 'п'},
{'R', 'Я'},
{'r', 'г'},
{'U', 'Ц'},
{'u', 'ц'},
{'W', 'Щ'},
{'w', 'щ'},
{'Y', 'Ч'},
{'y', 'ч'}
};

stгiпg s; щиile((s = Coпsole.ЯeдdLiпe()) != пцll) {
Coпsole.ЩгiteLiпe(
пeщ stгiпg(s.Select(c => tгдпs.CoпtдiпsКeч(c) ? tгдпs[c] : c).
Toдггдч()
)
);
}
}
}


Tиe sиoгtest code щiпs.

# Exдmple Iпpцt дпd Oцtpцt

Iпpцt:

As we know, the goal of every struggle is victory. But if the proletariat is to achieve victory, all the workers, irrespective of nationality, must be united. Clearly, the demolition of national barriers and close unity between the Russian, Georgian, Armenian, Polish, Jewish and other proletarians is a necessary condition for the victory of the proletariat of all Russia.

We are for the withering away of the state, and at the same time we stand for the strengthening of the dictatorship of the proletariat, which represents the most powerful and mighty of all forms of the state which have existed up to the present day. The highest development of the power of the state, with the object of preparing the conditions of the withering away of the state: that is the Marxist formula. Is it "contradictory"? Yes, it is "contradictory." But this contradiction is a living thing and wholly reflects the Marxist dialectic.

Oцtpцt:

дs щe кпoщ, tиe goдl of eveгч stгцggle is victoгч. Бцt if tиe pгoletдгiдt is to дcиieve victoгч, дll tиe щoгкeгs, iггespective of пдtioпдlitч, mцst бe цпited. Cleдгlч, tиe demolitioп of пдtioпдl бдггieгs дпd close цпitч бetщeeп tиe Яцssiдп, Geoгgiдп, дгmeпiдп, Polisи, Jeщisи дпd otиeг pгoletдгiдпs is д пecessдгч coпditioп foг tиe victoгч of tиe pгoletдгiдt of дll Яцssiд.

Щe дгe foг tиe щitиeгiпg дщдч of tиe stдte, дпd дt tиe sдme time щe stдпd foг tиe stгeпgtиeпiпg of tиe dictдtoгsиip of tиe pгoletдгiдt, щиicи гepгeseпts tиe most poщeгfцl дпd migиtч of дll foгms of tиe stдte щиicи идve existed цp to tиe pгeseпt dдч. Tиe иigиest developmeпt of tиe poщeг of tиe stдte, щitи tиe oбject of pгepдгiпg tиe coпditioпs of tиe щitиeгiпg дщдч of tиe stдte: tидt is tиe Mдгxist foгmцlд. Is it "coпtгдdictoгч"? Чes, it is "coпtгдdictoгч." Бцt tиis coпtгдdictioп is д liviпg tиiпg дпd щиollч гeflects tиe Mдгxist diдlectic.

• Welcome to PPCG and thanks for using the Sandbox! Unfortunately, this challenge is essentially the same as this question. Also, please don't write your specs in this "stylised" manner. It greatly hurts the searchability of your post. Aug 20 '16 at 22:03
• Your code is also stylized. Does your code run properly? Aug 20 '16 at 22:34
• @ColdGolf And do you think I'd stylize my post by hand? Aug 21 '16 at 2:13
• @FryAmTheEggman OK, thank you. I now see my challenge was pointless and won't post it to the main. Aug 21 '16 at 2:14
• Nothing is pointless: now you you know more and can come up with a better challenge! :) Aug 21 '16 at 2:17
• @ColdGolf OK you were right, I messed up the stylization. {'b', 'и'} - here is a bug. Sorry. Aug 21 '16 at 2:22
• @gaazkam Does your code, with the stylized цsiпg Sчstem;, run properly? Aug 21 '16 at 2:39
• @ColdGolf I regard people of CodeGolf intelligent enough to find out they'd have to unstylize this code ^^ :) Aug 22 '16 at 7:11
• @gaazkam I see. Aug 22 '16 at 17:34

### Alphabet ripple

You must print out this exact text:

abcdefghijklmnopqrstuvwxyzzyxwvutsrqponmlkjihgfedcba
abcdefghijklmnopqrstuvwxyyyyxwvutsrqponmlkjihgfedcba
abcdefghijklmnopqrstuvwxxxxxxwvutsrqponmlkjihgfedcba
abcdefghijklmnopqrstuvwwwwwwwwvutsrqponmlkjihgfedcba
abcdefghijklmnopqrstuvvvvvvvvvvutsrqponmlkjihgfedcba
abcdefghijklmnopqrstuuuuuuuuuuuutsrqponmlkjihgfedcba
abcdefghijklmnopqrsttttttttttttttsrqponmlkjihgfedcba
abcdefghijklmnopqrrrrrrrrrrrrrrrrrrqponmlkjihgfedcba
abcdefghijklmnopqqqqqqqqqqqqqqqqqqqqponmlkjihgfedcba
abcdefghijklmnopppppppppppppppppppppponmlkjihgfedcba
abcdefghijklmnoooooooooooooooooooooooonmlkjihgfedcba
abcdefghijklmnnnnnnnnnnnnnnnnnnnnnnnnnnmlkjihgfedcba
abcdefghijklmmmmmmmmmmmmmmmmmmmmmmmmmmmmlkjihgfedcba
abcdefghijkllllllllllllllllllllllllllllllkjihgfedcba
abcdefghijkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkjihgfedcba
abcdefghijjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjihgfedcba
abcdefghiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiihgfedcba
abcdefghhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhgfedcba
abcdefggggggggggggggggggggggggggggggggggggggggfedcba
abcdeffffffffffffffffffffffffffffffffffffffffffedcba
abcdeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeedcba
abcddddddddddddddddddddddddddddddddddddddddddddddcba
abccccccccccccccccccccccccccccccccccccccccccccccccba
abbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbba
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa


### Specs

• You may do it in all-uppercase instead of all-lowercase.
• A single leading and trailing newline are allowed
• You may not output an array of strings - the delimiter must be a newline

### Scoring

This is . Program with lowest byte-count wins.

• Seriously, another alphabet challenge ._. Aug 21 '16 at 14:23
• Duplicate, too lazy to find. Aug 21 '16 at 14:27
• @LeakyNun you're too lazy to search through your own challenges...? Aug 21 '16 at 20:49
• @trichoplax I don't feel like wasting my time to search for the duplicate. Aug 21 '16 at 20:57
• @LeakyNun I knew what you meant - I was just making a poor joke that you would only need to search your own challenges since you wrote every alphabet challenge... Aug 21 '16 at 21:15
• @LeakyNun, this Show tree rings age? Aug 23 '16 at 10:50
• @LeakyNun what exactly is the duplicate? I'd like to know. Aug 27 '16 at 16:39
• @ConorO'Brien this Aug 27 '16 at 16:46

# The Note-Takers Dream

## Meta

This challenge requires more than most challenges. Is it to much?

The goal here is simple. Turn my notes into text. To this end, any tool or web service may be employed.

## Specification

• Input
• An image of handwritten notes, stored an some data structure (this structure is flexible)
• This image will be a direct, over-head shot of a single page of graph paper
• Notes
• The notes are taken on graph paper with one character per box
• The characters will be printable ASCII
• An empty box should be considered as a single Space character
• There is an implicit New Line character between each row
• Output
• A string of the text represented in the image
• This image should be trimmed of leading white space
• Trailing white space is fine
• Score
• The score is the sum of the Levenshtein distances between required outputs and actual outputs
• Lowest score wins

## Test Cases

Coming soon. . .

• Mathematica will win, and everyone else will weep Aug 30 '16 at 22:42
• So basically codegolf.stackexchange.com/q/28207/194 with a larger character set and probably a smaller test set. It's effectively a dupe IMO. Aug 31 '16 at 7:52
• Golfing in ABBYY FineReader Engine has never been so exciting. Aug 31 '16 at 14:45