# What is the Sandbox?

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

See the Sandbox FAQ for more information on how to use the Sandbox.

## Get the Sandbox Viewer to view the sandbox more easily

To add an inline tag to a proposal use shortcut link syntax with a prefix: [tag:king-of-the-hill]

# 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 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. – John Dvorak 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" – Lause 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. – John Dvorak 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. – John Dvorak 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. – Lause 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 – John Dvorak 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? – Lause 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. – John Dvorak 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. – John Dvorak 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. – Lause 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? – Peter Taylor 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 – Lause 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. – Peter Taylor 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? – Peter Taylor 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? – Fund Monica's Lawsuit 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. – Nathan Merrill 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? – Zgarb May 10 '16 at 21:36 • i will see what cops and robbers is – Abr001am May 10 '16 at 21:39 • @NathanMerrill this is not a code golf so i dont see the point of introducing esolangs here – Abr001am 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. – Nathan Merrill 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. – Peter Taylor 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? – Peter Taylor 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. – Abr001am 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. – Abr001am 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. – Patrick Roberts 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? – Patrick Roberts Jun 17 '16 at 20:41 • Yes, yes it is. – weatherman115 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. – Patrick Roberts 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. – Fatalize Jun 23 '16 at 13:01 • Really? Anything to suggest instead? Just "best" is usually no good for Stack Exchange... – hippietrail 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. – Martin Ender Jun 23 '16 at 13:30 • Hmm well OK whatever. – hippietrail 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. – Peter Taylor 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. – user2428118 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. – Peter Taylor 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 99 101 adf 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. – Peter Taylor Jul 13 '16 at 16:14 • Hi Peter, thanks for this. I've edited accordingly – cianius Jul 13 '16 at 16:16 • – Peter Taylor 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. – cianius Jul 14 '16 at 7:30 • i edited example to clarify this Peter :) – cianius 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. – Rohan Jhunjhunwala 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? – Martin Ender 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? – AdmBorkBork 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. – Martin Ender 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... – TuxCrafting Aug 3 '16 at 11:31 • @TùxCräftîñg no – Shaun Wild Aug 3 '16 at 11:32 • Disallowing language are a thing to avoid when writing challenges – TuxCrafting 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! – Shaun Wild 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. – Peter Taylor 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? – trichoplax 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? – trichoplax 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 There you go, your first "Hello world" is displayed on your terminal. You think about your next step into becoming a wizard. 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. – Rɪᴋᴇʀ May 4 '16 at 14:06 • Pyth: \H (Guess what the second language is) – Leaky Nun 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? – Rɪᴋᴇʀ May 4 '16 at 14:09 • Then the submission above would score 0. – Leaky Nun May 4 '16 at 14:09 • (To OP) Maybe you would need to add some more rules – Leaky Nun May 4 '16 at 14:11 • @KennyLau no? 2/2 = 1 – Rɪᴋᴇʀ May 4 '16 at 14:11 • @EᴀsᴛᴇʀʟʏIʀᴋ It can be fed into itself for one more pass... – Leaky Nun 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. – nobe4 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. – Fatalize 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... – nobe4 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. – AdmBorkBork May 4 '16 at 14:22 • Also this one, which is practically a duplicate, just with numbers instead of "Hello, world." – AdmBorkBork May 4 '16 at 14:26 • Yeah, I haven't seen all this, I guess I'll start searching for another idea instead ;) – nobe4 May 4 '16 at 14:29 • Also, welcome to PPCG! (I forgot to mention that earlier). Hope you enjoy yourself here! – AdmBorkBork 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. – Alex A. 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 Say they need an upgrade Reinstall the software Ask for a dump 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? – Peter Taylor Aug 8 '16 at 21:41 • whoops should have tagged it as such @PeterTaylor – Rohan Jhunjhunwala 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?) – FryAmTheEggman 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 – Rohan Jhunjhunwala 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 – Peter Taylor Aug 16 '16 at 7:10 • @PeterTaylor FYI there's something wrong with that link's formatting – tbodt Aug 16 '16 at 18:07 • There isn't any formatting. I just pasted the link directly. And it works for me. – Peter Taylor Aug 16 '16 at 19:11 • @PeterTaylor hmm, seems to have fixed itself... – tbodt 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. – Nathan Merrill 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. – Peter Taylor 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 – Destructible Lemon Aug 19 '16 at 1:45 # Щoгкeгs of tиe щoгld, цпite! # 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. – FryAmTheEggman Aug 20 '16 at 22:03 • Your code is also stylized. Does your code run properly? – Buffer Over Read Aug 20 '16 at 22:34 • @ColdGolf And do you think I'd stylize my post by hand? – gaazkam 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. – gaazkam Aug 21 '16 at 2:14 • Nothing is pointless: now you you know more and can come up with a better challenge! :) – FryAmTheEggman Aug 21 '16 at 2:17 • @ColdGolf OK you were right, I messed up the stylization. {'b', 'и'} - here is a bug. Sorry. – gaazkam Aug 21 '16 at 2:22 • @gaazkam Does your code, with the stylized цsiпg Sчstem;, run properly? – Buffer Over Read Aug 21 '16 at 2:39 • @ColdGolf I regard people of CodeGolf intelligent enough to find out they'd have to unstylize this code ^^ :) – gaazkam Aug 22 '16 at 7:11 • @gaazkam I see. – Buffer Over Read Aug 22 '16 at 17:34 ### Alphabet ripple You must print out this exact text: abcdefghijklmnopqrstuvwxyzzyxwvutsrqponmlkjihgfedcba abcdefghijklmnopqrstuvwxyyyyxwvutsrqponmlkjihgfedcba abcdefghijklmnopqrstuvwxxxxxxwvutsrqponmlkjihgfedcba abcdefghijklmnopqrstuvwwwwwwwwvutsrqponmlkjihgfedcba abcdefghijklmnopqrstuvvvvvvvvvvutsrqponmlkjihgfedcba abcdefghijklmnopqrstuuuuuuuuuuuutsrqponmlkjihgfedcba abcdefghijklmnopqrsttttttttttttttsrqponmlkjihgfedcba abcdefghijklmnopqrssssssssssssssssrqponmlkjihgfedcba 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 ._. – TuxCrafting Aug 21 '16 at 14:23 • Duplicate, too lazy to find. – Leaky Nun Aug 21 '16 at 14:27 • @LeakyNun you're too lazy to search through your own challenges...? – trichoplax Aug 21 '16 at 20:49 • @trichoplax I don't feel like wasting my time to search for the duplicate. – Leaky Nun 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... – trichoplax Aug 21 '16 at 21:15 • @LeakyNun, this Show tree rings age? – manatwork Aug 23 '16 at 10:50 • @LeakyNun what exactly is the duplicate? I'd like to know. – Conor O'Brien Aug 27 '16 at 16:39 • @ConorO'Brien this – Leaky Nun 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 – Rohan Jhunjhunwala 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. – Peter Taylor Aug 31 '16 at 7:52 • Golfing in ABBYY FineReader Engine has never been so exciting. – Andreï Kostyrka Aug 31 '16 at 14:45 # Print the name of the language The goal of this challenge, as implied in the title, is to print the name of the language with a program in said language, in as few bytes as possible. But that would be too easy, right ? So to add a litle bit of challenge, you are not allowed to use any characters included in the language's name. # Rules • Each submission must be a full program. • The program must take no input, and print the name of the language to STDOUT plus an optional trailing newline, and nothing else. • The program must not write anything to STDERR. • Usual loophole rules apply • Submissions are scored in bytes, in an appropriate encoding, usually (but not necessarily) UTF-8. • This is , so the shortest program (in bytes) wins. # Sandbox After checking, I don't think this question is a dupe. Are there any grammatical mistakes ? (English isn't my first language) Are there any rules that should be added (like banning languages created after the challenge ?) Should I add any further specification ? • Do X without Y is discouraged. We're talking about your question in Code Golf Chat right now. (And now the conversation's moved on...) – wizzwizz4 Sep 1 '16 at 8:39 • @wizzwizz4 Would removing the "not use characters in the program name" rule make it better ? I didn't want the challenge to become "who has the shortest printf command" – Lamedonyx Sep 1 '16 at 8:45 • At the moment it's "who has the shortest program name". – wizzwizz4 Sep 1 '16 at 8:48 • If the challenge is in danger of becoming "who has the shortest printf command" then rather than trying to fix it you should consider throwing it away and looking for an interesting challenge. – Peter Taylor Sep 1 '16 at 11:42 # Make a dummy C program We all know the feeling. You have written a short, efficient and readable one-liner that's the perfect solution to the problem. Then your code-illiterate boss looks over your shoulder and is not very happy that you've spent an entire paid hour producing "nothing". You could politely explain the situation to your boss, complete with a demonstration that your code does what it should. Or, because talking to people is Hard Work™, you could fake it. Your task is to write a program that takes a list of keywords as input, and outputs dummy C code that looks like it does something to do with those words. Sandbox note: not happy with the wording in final bit here. For example, if the inputs were integral, formula, math, proof, fit and square, the output might be: #include <math.h> #include <setjmp.h> double* squarefit(int integral, float* mathproof) { char **integralb={{0}}; double square[integral]; int i=0; //integral math formula fit for(integralb[0][0]=(char)erff(*mathproof);isnan((double)++integral);i++) { return hypot(sqrt(square[integral]),integral)?square:square; printf(*integralb,integral,*mathproof); } setjmp((struct __jmp_buf_tag*)mathproof+(int)(abs(--integral)-expm1l(integral))); longjmp(0,0); return square; }  Although it doesn't have to do anything, or even run successfully properly, the source code produced by your program must compile in gcc (no additional options) without fatal errors. You do not need to provide a main function; if you don't, expect the line int main(void){} to be appended to the output file before it is compiled. This is a , so the best-liked answer will win. However, voters should keep these questions in mind when assessing the submissions: • Does the produced source code look like it does the expected task? Yes. • Does the produced source code look like it has taken a long time to produce? Yes. • Do different inputs result in the same program, just with different variable names? No. • Does the produced source code look like the same code repeated over and over? No. • Do your parents, grand-parents, co-workers or other "not computer people" think the produced source code was something to do with the input keywords (optional)? Yes. • Would you think the produced source code was written by a person with knowledge of the C language, if you did not know that it was just dummy code (optional)? Yes. • Does the code look readable (e.g. ungolfed)? Yes. Not all of the standard loopholes apply for this challenge. For example, you mignt use external resources, such as library files or an indexable website. However, voters should use their discretion as to what is reasonable and what is not (such as expecting the "keywords" to be in a format that includes a high-quality, valid C program). Sandbox note: how to finish challenge body? • Is this a language-specific challenge? – user56309 Sep 29 '16 at 17:05 • @tuskiomi No, it's open to all languages. – wizzwizz4 Sep 29 '16 at 17:06 • Generally it's a good Idea to separate your challenge into five sections: the intro, summary, input, output, and examples. I'd recommend you do so here as well. – user56309 Sep 29 '16 at 17:07 • @tuskiomi Thanks, will do. Give me 6 to 8 weeks... – wizzwizz4 Sep 29 '16 at 17:11 • @tuskiomi I disagree. There are plenty of ways to organize a challenge effectively. However, this challenge looks like it might suffer a bit from the "art contest" issue, so be wary wizz. – Calvin's Hobbies Sep 29 '16 at 17:31 • @HelkaHomba I never said that it's the ONLY way to organize challenges to be effective, I said that generally it's a good idea to do that format. – user56309 Sep 29 '16 at 17:34 • @HelkaHomba That's the format I often use, and I plan to split it into headings. What do you mean by "art contest issue"? – wizzwizz4 Sep 30 '16 at 6:28 • I mean the judging is up to the whim of the voters own opinions and knowledge of how C code should look. We've had issues before with challenges like "draw the prettiest picture" which is plainly an art, not programming contest, and those kind of thing rarely go over well, often close voted as "primarily opinion based". This challenge (and all pop-cons really) suffer from similar issues. I'm not personally against this challenge or art contests, but it's just an issue you may need to face. – Calvin's Hobbies Sep 30 '16 at 6:35 • @HelkaHomba Do you have suggestions as to which questions to change / remove / reword to stop it being bad subjective? – wizzwizz4 Sep 30 '16 at 6:45 • I kind of like this, but I bet it would be closed as too broad. Anything from the program you provided to main(){integral+formula+square+proof+fit==math?return 0:return 1;} would be allowed. – MD XF May 26 '17 at 20:13 • @MDXF That wouldn't be valid if the inputs foo, bar, baz, fizz, buzz, fred would result in main(){foo+bar+baz+fizz+buzz==fred?return 0:return 1;}. Also, gcc gets very cross that none of those names are defined, so it won't compile. So actually that wouldn't be allowed. Also note that that is a boring submission to a popularity-contest. – wizzwizz4 May 27 '17 at 8:06 # Three-way meta-quine polyglot code-golf Produce a program A such that running it in language A produces Program B, and running program A in language B produces program C. Program B, when run in language B produces Program A, and running program B in language A produces program C. Program C, when run in language A or language B, prints "Wrong language!". Program | Language | Result --------|----------|---------- A | A | Program B B | B | Program A A | B | Program C B | A | Program C C | A | "Wrong language!" C | B | "Wrong language!"  Your answer should use this template: # Language A/Language B, {a bytes} + {b bytes} = {total bytes} bytes Language A: a code  Language B: b code  Source: # Language A/Language B, <a bytes> + <b bytes> = <total bytes> bytes Language A: a code Language B: b code  • None of these programs should take input. • Different versions of the same language count DO NOT as different languages. - Languages A and B must be distinct. • You must not read your own source code from a file. Programs may not be empty • Standard loopholes apply. This is , the smallest sum of the byte counts Program A and B wins. • Downvote reason? – noɥʇʎԀʎzɐɹƆ Nov 8 '16 at 20:23 • It's probably not possible. I'll revert my downvote if you can find a solution within 24 hours of this comment. – MD XF Jun 7 '17 at 21:39 # Urinal Discomfort! This question springboards off of Positional Bathroom Etiquette, while adding an extra twist. ### Background I'm going to take @Nick Frev 's formulae for the total discomfort of a urinal spot dist(x,y) = linear distance between person x and person y in Urinal Units discomfort(x) = sum(1/(dist(x,y)*dist(x,y))) for all persons y excluding person x total_Discomfort = sum(discomfort(x)) for all x short_urinal_discomfort = discomfort_from_surroundings + 1/9 (inherent_discomfort)  Your task is to put a person into the spot with the least total discomfort. However, now you have big and small urinals. The small ones, obviously, cause a little inherent discomfort, so we prefer to not use those if we have a choice. ## The Challenge ### Input/Output Your program will take in a string of 1,0,i,o to represent the row of urinals. 1 represents a person in a tall urinal, 0 is an empty tall urinal, i is a full short urinal, and o is an empty short urinal. Using the above formulae, build a program that will replace an empty urinal with the correct placement of the next person(0->1 or o->i). • The short urinals have an inherent discomfort of 1/9 which will be added onto the discomfort provided by the surroundings. • The door is to the right of the row, so the urinals fill up right to left, because you have to pee really bad and can't walk further than you have to. Input Output 000 001 101 111 1000001 1001001 101010101 101010111 000o 001o 100o 100i oo0oooo oo1oooo 11000ii 11010ii ## Any tips would be super helpful More test cases maybe? Or more clarification? # Stump the OEIS! The OEIS is a wonderful database of integer sequences, but occasionally, there are code golf problems that generate integer sequences not found in the OEIS. Your challenge is to write some code that generates a sequence that meets all of the following criteria: 1. Sequence must not exist in the OEIS. Prove this by providing a link to the search for your sequence showing 0 results, such as this: 1,2,6,81,35246. In the spirit of good faith, please do not generate a sequence that is merely an existing sequence offset or multiplied by some constant. 2. The sequence must be non-repeating, non-oscillating, etc. Formally, there must not exist a subsequence S with finite length L, that begins at index I such that the subsequence from [I+kL] to [I+(k+1)L-1] for every k is identical to S. Such an invalid sequence would be 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, ... because the subsequence 1, 2, 3 beginning at index 1 with length 3 also exists as the subsequence from 4 to 6, from 7 to 9, from 10 to 12, etc. 3. The sequence must contain a minimum of 3 distinct integers. 4. The sequence must be deterministic, e.g. there must not be any element of randomness in the generation of your sequence. Every time your program is run, it must provide the same exact sequence. Please write code that provides as many integers in your sequence as feasible. At least 20 is recommended, though sequences that grow incredibly fast can provide fewer, provided you also give a proof that your code would produce that number if given enough time. This will be a problem, so the entry with the fewest number of bytes wins. A bonus of -20% can be applied to your score if, in addition to your sequence, you can also provide some mathematical justification for your sequence being included in the OEIS in the future. Standard loopholes are disallowed, as well as sequences that are simply "this sequence is just the handful of numbers I came up with to fit this problem." • You say "must contain an infinite number of entries not 0 or 1", then go on to talk about finite sequences, so I'm not sure what you're looking for here. – Geobits Nov 17 '16 at 17:44 • Changed it to "The sequence, if infinite, must contain" blah blah blah – Gabriel Benamy Nov 17 '16 at 17:45 • This is definitely going to be closed as "Too broad" - if it isn't closed first as "Unclear what you're asking" because of the impossibility of testing whether "this sequence is just the handful of numbers I came up with to fit this problem." – Peter Taylor Nov 17 '16 at 17:52 • @PeterTaylor If I removed the possibility of finite sequences, then IMO that second possibility goes away. As for being closed for too broad, there have been problems that don't have a single goal that have done well, such as Does this code terminate? that inspired a lot of very creative answers. – Gabriel Benamy Nov 17 '16 at 17:59 • Its pretty easy to fill most of the requirements you've listed here: all you need to do is combine two different OEIS sequences (multiply or add). Restriction 3 should be changed to "Your sequence must contain at least 3 distinct terms". I'd also definitely recommend disallowing finite sequences, as well as the 20% bonus (which is very ambiguous) – Nathan Merrill Nov 17 '16 at 18:33 • @NathanMerrill That's a good idea for a change to #3, but as for being able to simply combine existing sequences, there's plenty of existing sequences like that are already in the OEIS even without necessarily being important. – Gabriel Benamy Nov 17 '16 at 18:44 • @GabrielBenamy right, its not necessarily a bad thing, its just that most sequences generated aren't going to be that interesting. Also, what's to stop me from simply adding a random "9" number to the beginning of the sequence, or replacing the first term with "9"? – Nathan Merrill Nov 17 '16 at 18:45 • Consider the family of sequences parameterised by x where S(x, n) = n >= x ? n+1 : n. Only a finite number of those sequences are either in OEIS or a linear transform of a sequence in OEIS. Are they caught by "just the handful of numbers I came up with to fit this problem"? IMO it's ambiguous. – Peter Taylor Nov 17 '16 at 19:22 • That's a good point. Is there any way to salvage this concept? – Gabriel Benamy Nov 17 '16 at 19:24 • This is similar to the question "print something with no results on google". It got closed for being a question about Google's database, not about code-golf, so this one will probably be closed too. – FlipTack Nov 19 '16 at 13:37 # Golf + Polyglot + Circle = ? In the original challenge, we asked you to do this: Program | Language | Result --------|----------|---------- A | A | Program B B | B | Program A A | B | Program C B | A | Program C C | A | "Wrong language!" C | B | "Wrong language!"  Now we're asking you to do this*: Program | Language | Result --------|----------|---------- 1 | 1 | Program 2 2 | 2 | Program 3 3 | 3 | Program 4 | ... | X | X | Program 1 --------|----------|---------- 1 | Any but 1| Any member of Set % 2 | Any but 2| Any member of Set % | ... | X | Any but X| Any member of Set % ------------------------------ Set % | Any lang | "Wrong language!"  (see original challenge for clarification) ## Rules • Do not grab source off of internet, or read own code from file • Programs don't have to be distinct - you can make a polyglot quine • Don't take input for any of the programs • Different versions of the same language count do as different languages. (although this is discouraged because it leads to boring solutions) • Standard loopholes apply ## Scoring Score is byte_count_of_program_one/2.75**languages_supported, the submission with the lowest score wins. ## Template Because of its length, the answer template is here. *not that I'm expecting X to be so large • +1 this comment if you think the title should be "Polyglot-Quine-Codegolf Returns!" – noɥʇʎԀʎzɐɹƆ Nov 23 '16 at 23:38 • +1 this comment if you think the title should stay the same – noɥʇʎԀʎzɐɹƆ Nov 23 '16 at 23:38 • Reply to this question if you have a better title – noɥʇʎԀʎzɐɹƆ Nov 23 '16 at 23:38 • I personally think the title is way too descriptive, but "polyglot-quine-codegolf" isn't really descriptive enough. The problem is, I don't currently have a better idea... – ETHproductions Nov 24 '16 at 0:12 # Signs in Permutations ### Introduction Let's take the permutations of 123. 123 132 213 231 312 321  We can insert signs in between the numbers and count how many > signs there are: 1 < 2 < 3 # 0 1 < 3 > 2 # 1 2 > 1 < 3 # 1 2 < 3 > 1 # 1 3 > 1 < 2 # 1 3 > 2 > 1 # 2  We can arrange this in a table with n corresponding to the number (in this case 3) and k corresponding to the number of > signs, you get this: ┌───┬───┬────┬─────┬─────┬────┬───┐ │n\k│ 0 │ 1 │ 2 │ 3 │ 4 │ 5 │ ├───┼───┼────┼─────┼─────┼────┼───┤ │ 1 │ 1 │ │ │ │ │ │ │ 2 │ 1 │ 1 │ │ │ │ │ │ 3 │ 1 │ 4 │ 1 │ │ │ │ │ 4 │ 1 │ 11 │ 11 │ 1 │ │ │ │ 5 | 1 │ 26 │ 66 │ 26 │ 1 │ │ │ 6 │ 1 │ 57 │ 302 │ 302 │ 57 │ 1 │ └───┴───┴────┴─────┴─────┴────┴───┘  ### Task Given an n and k, print the number in the table corresponding to that n and k. Remember, this is , so the code with the fewest bytes wins. Related OEIS sequence I want to post the question here to make sure it is suitable. # Question: Word Equations Given a word equation, the solution must output the answer. My definition of a 'word equation' is an equation where the operators are words. The operators will be spelt as add minus times divide The solution must take one input The solution must give one output ### Examples: Input: 7 add 8 Output: 15 Input: 9 times -2 Output: -18 Input: 24 divide 2 Output: 12 Input: 4 minus 5 Ouput: -1 You are not required to deal with divide by zero errors. Fewest characters will win Feedback is welcomed • What is the winning criterion? – acrolith Dec 2 '16 at 22:14 • @daHugLenny fewest characters, should have known to include that – george Dec 2 '16 at 22:59 • Be aware that you will receive many answers in the form: substitute words with corresponding char (+-*/), then evaluate the string you got. Non necessarily a bad thing, just pointing this out in case you expect people to build a calculator from scratch. – Leo Dec 3 '16 at 18:41 • @Leo the way I expected to solve it was by char substituting. However building a calculator from scratch only using + and - could be an interesting challenge – george Dec 3 '16 at 18:55 ## GoL flooding Considering a 1000x1000 grid (no wrapping, borders dead), your task is to grow the maximum "stable" population from the fewer individuals. For the purpose of this challenge, the definition of stable is a configuration who repeat with a period of less than hundred(100) generations. # Scoring Your score is lowest number of live cells in your stable population divided by the number of initialy live cells, highest score win meta post about on topicness • How many generations does the simulation run before the score is tabulated? – AdmBorkBork Dec 8 '16 at 13:48 • @TimmyD I would say 10.000 but feel free to suggest a better number if you think it could improve – Sefa Dec 8 '16 at 14:07 # Convenient Palindromic quine golf, Cops cops-and-robbers This is the cops thread, the robber's thread is here. ## Cop's Challenge A program is conveniently palindromic if it is equal to the string derived when its reverse has all its parentheses (()), brackets ([]), and braces ({}) flipped. No other characters are special and require flipping. (<> are sometimes paired but often not so they are left out.) copied from this challenge. Write a conveniently palindromic program that prints its own source. This is the robber's goal: • Remove byte(s) from the cop's program so that the resulting program: • prints the original source, or • prints the new modified source • Resulting program need not be a convenient palindrome ## A counterexample ### JavaScript (function$(){console.log('('+$+'())')}())//((){('(()'+$+')')gol.elosnoc}()\$ niotcnuf)


is easily cracked because the robber can remove all the characters past the comment and it will still print its own source.

## Rules

• Program must be longer than one character
• No reading from a file or grabbing from an external resource
• Submissions that aren't cracked for 7 days are marked as "safe", and cannot be cracked anymore
• Cop's submissions after XX/XX/XX are non-competing (can be pushed back depending on popularity), so there are still robbers around to crack it
• The shortest safe solution in bytes wins.
• Robbers won't have a chosen winner

• This is basically just a "comment-free palindromic quine" challenge, right? When those challenges have been run elsewhere, the comment-freedom has been verified via brute forcing rather than via a robber, and I suspect that the robbers might not have much to do here. (That said, some languages are slow enough that brute-forcing their correctness would be difficult.) In other news, you should probably require proper quine rules, even if we can't quite define them; under your current rules, 1 is a valid palindromic quine in PHP. – user62131 Dec 9 '16 at 22:41
• I would possibly change the palindrome restriction to convenient palindromes, as these are way easier to implement in most common languages such as JS and Python. – ETHproductions Dec 9 '16 at 23:01
• @ais523 1. Yas. That was my aim! 2. It's difficult to implement a brute-force solution for a longer submission, how would that work? 3. Program must be longer than one character 4. Thanks. – noɥʇʎԀʎzɐɹƆ Dec 10 '16 at 14:27
• 11 then :-P. Also, in a way I think this might be more interesting with true palindromes, as it forces you to hide the backwards string somehow, but I agree that it would disqualify a lot of languages. – user62131 Dec 10 '16 at 14:40
• @ais523 I'll do a true palindrome one then a convenient palindrome one later, perhaps? (also 11 then means ?) – noɥʇʎԀʎzɐɹƆ Dec 10 '16 at 14:44
• @ais523 When those challenges have been run elsewhere, they have? – noɥʇʎԀʎzɐɹƆ Dec 10 '16 at 14:51
• Neither this challenge nor this challenge has the same task as yours, but they both disallowed comments in much the same way as this one (i.e. by ensuring that deleting from the program breaks it). – user62131 Dec 10 '16 at 15:27

# Prelude:

Joke languages are allowed.
Submissions' scores will vary depending on whether they'll be made in a joke language, golfing language or a Turing complete language, don't worry if your score is high just because you chose a TC language.
That being said, let's get right into the challenge...

# Challenge:

Make a program as close as possible to the language name and document what it does in the description.

# Scoring/rules:

(will assume a simple language I made up, called Printr that has only a print() command that can take a argument to print but doesn't have to)

• Submissions that contain more than a 1/2 of whole language name in a string (ex. print("Printr")) are banned.
• Submissions must not throw any errors/exceptions/warnings (writing to an error stream is okay though).
• +1 for every char away from language's name (ex. print("r") is 4 chars away, (""), +4 points)
• Submissions need to contain (at least once) the language name "in a row" excluding nonalphanumeric characters and ignoring case (ex. print(" *@)!R") is okay, print("lolz R") is not okay)
• Duplicates of the name will be counted as other characters (ex. print("r") print("r") is still 4+1 [space]+10=15).

By looking as close as the language I mean having the least score (since scoring is based on other characters than the language name itself.

# Example:

## Printr, score 4:

print("r")

This program prints "r" then quits.

• is it allowed to throw an error? – FlipTack Dec 18 '16 at 14:00
• @Flp.Tkc, good question, errors shouldn't be allowed (syntax error be like). – n4melyh4xor Dec 18 '16 at 14:07
• What about a warning to STDERR? Stray error output is allowed by default on meta... – FlipTack Dec 18 '16 at 14:19
• @Flp.Tkc, should be okay. – n4melyh4xor Dec 18 '16 at 14:24
• ><>, in ><>, score 0, infinite loops. – redstarcoder Dec 18 '16 at 15:56
• or actually if we're excluding non-alphanumeric characters, this could also be golfed down to > or empty depending on if outputting "something smells fishy..." is a valid program. – redstarcoder Dec 18 '16 at 16:00
• in brainfuck you can just write brainfuck and it won't do anything... – FlipTack Dec 19 '16 at 17:31

# Print number of possible values of X if:

• Code 1: X is dividable by 3, X contains the number 3 and input() < X < 10000
• Code 2: X is dividable by 7, X contains the number 2, X doesn't contain the number 3 and input() < X < 5000

Sub-Challenge:

Do the same but instead of printing the number, print the values

Disclaimer: This is my first code golf challenge, and it's very simple, but could bring up some really short answers and cool languages

• First thing: Sub-challenges are not a good idea. People will write the shortest code they can and just disregard the sub-challenge. – Stewie Griffin Jan 16 '17 at 19:49
• Should you output the sum of the numbers from both two bullet points, in one? I don't think it benefits the challenge to have two different upper limits. I can see why you want it there, but I personally don't think it's a good thing. This needs some good test cases. – Stewie Griffin Jan 16 '17 at 19:52
• Those were actually different puzzles, sorry! – endriklos977 Jan 17 '17 at 12:10
• Two different independent puzzles in one challenge is not a very good idea either I'm afraid. I think it would be better to use the same upper limit and require the numbers from both 1 and 2 together, I.e. the union of the two sets. – Stewie Griffin Jan 17 '17 at 12:23