# 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".

Get the Sandbox Viewer to view the sandbox more easily!

# What day is it today? atomic-code-golf

Given a date y4y3y2y1-m2m1-d2d1, output the day in the week w. 0 as Sunday, 1 as Monday, and so on. You can assume the date is valid, and we use the current date rule and leap rule.

Each submission should be written in this specific programming language:

• A program consists of a mapping from string of digits to digits, and a sequence of instructions.
• Each instruction has the format: var=[var|dgt],[var|dgt],...,[var|dgt], which assigns the value of looking up the string constructed by concatenating the values of the right hand side elements ([var|dgt],[var|dgt],...,[var|dgt]) together in the table and put it into the var on the left.

A program is valid if:

• None of the lookup step fails for all valid input date.
• Given any valid date in the format mentioned above (initially assigned to the 8 variables y4 y3 y2 y1 m2 m1 d2 d1), after the program is run, the correct result is assigned to the variable w.

You can create as many variables as you like(though bounded by amount of instructions), each variable only containing a digit.

Solution win if there's no strictly better solution, aka. no solution that take less or same amount of items in mapping table, less or same amount of instrucions, and at least one of amounts of items and instructions is less.

For example, this is a solution that wins:

# 3652425 items 1 instruction

003000101 -> 6
003000102 -> 0
003000103 -> 1
...
993991231 -> 5
-------------
w=y4,y3,3,y2,y1,m2,m1,d2,d1

Here, the 3 on 3rd position can be used without any extra cost. This can be used to create multiple mappings, and sometimes save elements when there are more mapping instructions.

A checker is provided here.

• I completely don't understand the entire You can have a mapping table and some instructions, each instruction write var=[var|dgt],[var|dgt],...,[var|dgt], meaning search the element [var|dgt],[var|dgt],...,[var|dgt]from table and put i into the var on the left. Failure on searching is not allowed. You can create as many variables as you like(though bounded by amount of instructions), each variable only containing a digit. part. – the default. Jun 15 '20 at 8:32
• @Adám I'm requiring using only this language – l4m2 Jun 15 '20 at 8:40
• @mypronounismonicareinstate That mainly mean the only operation is lookup, there's nothing like plus, multiply or whatever – l4m2 Jun 15 '20 at 8:41
• @l4m2 I still do not understand a word. The whole proposal definitely requires a serious rewrite. – the default. Jun 15 '20 at 8:42
• @mypronounismonicareinstate If it hadn't needed some more time it isn't here – l4m2 Jun 15 '20 at 8:45
• "Solution win if there's no strictly better solution" is not a valid winning criterion because it allows multiple winners. – Bubbler Jun 15 '20 at 9:23
• @Bubbler Multiple winners is common – l4m2 Jun 15 '20 at 9:34
• @l4m2 Do you mean something like ties in code golf? IMO, code golf ties are fine because they can be seen as equally good, while your criterion is not because it allows potentially multiple answers that can't be compared to each other at all. – Bubbler Jun 15 '20 at 9:44
• @Bubbler I mean like multiple languages each only comparing to self – l4m2 Jun 15 '20 at 9:50
• @l4m2 The winning criterion is the guide to optimize one's solution in one direction. "Shortest solution in each language wins" does not harm this spirit. Yours don't give which one to optimize for: mapping table size or instruction size? – Bubbler Jun 15 '20 at 10:05
• @Bubbler Your link claims you wrong – l4m2 Jun 15 '20 at 11:59
• @l4m2 OK, let me say it in a different way. You already showed a "winning" solution with minimal instructions. Then there will be a "winning" solution with minimal table, and then there can be thousands of "winning" solutions in between. Given any "winning" solution, one can tweak a little to get another "winning" solution. Do you really think it is fun? – Bubbler Jun 15 '20 at 23:02
• @Bubbler Yea an exact bound of table size for each instruction count, if exist, makes its sense – l4m2 Jun 16 '20 at 5:06
• @Bubbler You don't like to see lots of winners because you think "win" is a big issue? – l4m2 Jun 16 '20 at 5:06

# Natural Language Identification Using Only Regular Expressions

For example:

const regex = /English(?=\w+ Hello World)|Spanish(?= Hola Mundo)/;

console.log('EnglishSpanish Hello World'.match(regex)); // English
console.log('EnglishSpanish Hola Mundo'.match(regex)); // Spanish

These wordlists are to be used, and words are to be rewritten entirely using the ASCII characters A-Z and a-z. Languages which use characters that cannot be easily transcribed into ASCII without special knowledge or firsthand experience in that language, are excluded.

For instance, the Albanian word is easily transcribed without special knowledge as te, so Albanian is allowed.

But the Arabic word من cannot be, so Arabic is excluded.

The regular expression must match the language exactly, so appending a list of all languages you are testing before each word is allowed. But however you organize this list, it must be the same for every word you test. See the example above for clarification.

## Sandbox Questions

Ideally, brevity of regex, accuracy of language identification, and number of languages taken into account by the regex should all be considered when determining the winner. But I have not decided on that yet, and am very open to suggestions.

In fact this is my first sandbox post and I hope someone can help me format this properly with good rules so that it makes for an interesting and fun challenge. I got this idea from some other contest somewhere where the goal was to identify languages with at least 60% accuracy. But I can't find it anymore.

• So only regex submissions are allowed? – user202729 Jul 22 '20 at 6:02
• Although there are options to "weight" the 3 scores differently, the easiest way is to require the other two scores to be larger than some limit (say, at least 2 languages and at least 60%) then compete for the shortest regex. – user202729 Jul 22 '20 at 6:04
• Also, are there any similar challenge before? – user202729 Jul 22 '20 at 6:05
• Yes, only regex is allowed. A very similar challenge I've found is this: codegolf.stackexchange.com/questions/49596/… – GirkovArpa Jul 22 '20 at 6:26
• Also this one, which is linked in the other: codegolf.stackexchange.com/questions/42206/… – GirkovArpa Jul 22 '20 at 6:27
• Pretty similar. But the huge size of the word list will make the solutions different. – user202729 Jul 22 '20 at 6:33
• you should specify a particular flavor of regex. – user202729 Jul 22 '20 at 6:34
• I would have said JavaScript but I thought there could be a winner for each programming language? – GirkovArpa Jul 22 '20 at 6:35
• If you decide to restrict to 2 languages, you may ask for a regex that matches words from list 1 and not match words from list 2. (it may (do anything|never matches) the words that are not in lists) – user202729 Jul 22 '20 at 6:37
• Good idea, I'll do that. – GirkovArpa Jul 22 '20 at 6:39

# Introduction

"Do not go gentle into that good night" is the title of a poem by 20th century English poet Dylan Thomas. If you've heard it before it was probably because you watched Interstellar, where it was quoted multiple times.

# Challenge

Your program (or function), if it chooses to not go gently, should take no input and print the following text, with an optional trailing newline:

Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.

Though wise men at their end know dark is right,
Because their words had forked no lightning they
Do not go gentle into that good night.

Good men, the last wave by, crying how bright
Their frail deeds might have danced in a green bay,
Rage, rage against the dying of the light.

Wild men who caught and sang the sun in flight,
And learn, too late, they grieved it on its way,
Do not go gentle into that good night.

Grave men, near death, who see with blinding sight
Blind eyes could blaze like meteors and be gay,
Rage, rage against the dying of the light.

And you, my father, there on the sad height,
Curse, bless, me now with your fierce tears, I pray.
Do not go gentle into that good night.
Rage, rage against the dying of the light.

This is , so smallest code in bytes wins.

# Sanbox

• Is this too bland/simple of a challenge? There's a lot of potential for compressing the poem, but it's not really complex.
• Just be careful it isn't marked as a duplicate of this – lyxal Aug 15 '20 at 3:09
• Is the string being different not enough? – nope Aug 15 '20 at 12:31
• I hope this one is different enough. Things like this are usually borderline since there are several lyrics question closed but some are still open. – null Aug 15 '20 at 14:51
• Despite some interesting repetition in this poem, I think the text compression methods used would be the same, making it a duplicate. – xnor Aug 16 '20 at 6:52

# Anti-codegolf, unique characters

## Objective

Write a program/method whose source code's characters are unique. You shall put as many characters as you can.

## Input

There is no input.

## Valid characters

All characters are identified by their Unicode code point. The following characters are invalid, and shall not appear in the source code nor the output:

• C0 and C1 control characters (U+0000 – U+001F and U+0080 – U+009F) except Character Tabulation (U+0009), Line Feed (U+000A), Line Tabulation (U+000B), Form Feed (U+000C), Carriage Return (U+000D), and Next Line (U+0085)

• Outputting these characters are banned, even if they have special effect on an output stream.
• Low and High surrogates (U+D800 – U+DFFF)

• Noncharacters (U+FDD0 – U+FDEF, and U+xxFFFE and U+xxFFFF for xx = 00 – 10)

• Code points that are outside of U+0000 – U+10FFFF

A character is valid otherwise. In particular, whitespaces, combining characters, and private uses, and even reserved characters are valid.

## Restrictions and output

The output shall be a string. This includes string returned by a function, or string printed to stdout, stderr, a file, or a dialog box.

The set of the characters in the source code shall be a subset of the set of the characters in the output. Note that the output doesn't need to consist of unique characters.

The output may be arbitrarily many strings, for which their concateration will be considered for the restriction above.

## Scoring

This is an anti-codegolf. The submission with the longest source code wins.

• Can we output though an error message? – Adám Aug 24 '20 at 4:37
• @Adám I'd permit it. – Dannyu NDos Aug 24 '20 at 4:45
• Explicitly stating the range of valid codepoints would be useful. – Bubbler Aug 24 '20 at 4:45
• So then any expression that generates an error message containing the offending line, followed by a comment symbol and all the unneeded characters, would be the perfect solution? – Adám Aug 24 '20 at 4:47
• @Adám Welp. Then I should add a restriction. – Dannyu NDos Aug 24 '20 at 4:48
• Be careful about that restriction. Putting restrictions on code is notoriously difficult to get right. – Adám Aug 24 '20 at 4:49
• Also, the languages whose inline comment starts with single char (say Python's # or APL's ), or any esolangs that ignore non-commands will likely get perfect score on any task solvable in that language. – Bubbler Aug 24 '20 at 4:53
• Not only that, many languages could probably just use an unfinished string (i.e. missing the closing quote) containing all the other necessary characters. – Adám Aug 24 '20 at 5:05
• @Adám What about now? – Dannyu NDos Aug 24 '20 at 5:08
• Did you intentionally remove the requirement that the output be longer than the input? – Adám Aug 24 '20 at 5:10
• What are "Reserved characters"? – Adám Aug 24 '20 at 5:10
• @Adám Yes. I tried to find a better restriction. – Dannyu NDos Aug 24 '20 at 5:10
• @Adám Reserved characters are code points that are not assigned a unicode character. – Dannyu NDos Aug 24 '20 at 5:11
• You've now banned line breaks. Lots of languages will have problems using only one-liners. – Adám Aug 24 '20 at 5:29
• [code-bowling]. – user202729 Aug 24 '20 at 5:36

# Gray codegolf

The gray code is a binary numeral system such that two successive values differ in only one bit.

Decimal Binary  Gray
0       0000    0000
1       0001    0001
2       0010    0011
3       0011    0010
4       0100    0110
5       0101    0111
6       0110    0101
7       0111    0100
8       1000    1100
9       1001    1101
10      1010    1111
11      1011    1110
12      1100    1010
13      1101    1011
14      1110    1001
15      1111    1000

# Challange

Print the first k Gray code numbers, starting from 0. The shortest code wins!

You may choose the output format as long as it's human-readable.

# Similar questions

• Why the strict output format, and why the arbitrary constant limit of 1000 (not taking an input number)? Also, possible dupe. – Bubbler Aug 28 '20 at 4:19
• When you say first 1000, is that decimal or binary? – Jo King Aug 28 '20 at 7:55
• The challenge I linked is code golf. – Bubbler Aug 28 '20 at 16:06
• @Bubbler nvm, it looks like I am banned from posting lol – Ilya Gazman Aug 28 '20 at 17:35
• printing a sequence and finding a number in a sequence tend to be very similar tasks. – Razetime Sep 1 '20 at 3:28

# B-a-NaN-a code-golfkolmogorov-complexityrestricted-source

Somewhat famously, 'B' + 'a' + + 'a' + 'a' returns BaNaNa in Javascript. You goal is to output precisely BaNaNa. However, to keep it more in the style of the original Javascript, you may not use:

• The bytes 78 or 110
• Whatever n or N are encoded as if your language uses a special encoding, or
• Any string literal containing the characters n or N

As a special note, I'd like your feedback as to if restricting numeric literals equal to 78 and 110 would be any good.

Additionally, this is my first question, and I'm aware that 'Do X without Y' is officially not super popular these days, but I frankly quite enjoy them, so I have no idea if this will be well-received or not. I'm hoping that the reference to the JS quirk is enough to make it interesting.

• Restricting numeric literals would just result in 77+1 or +"78" or whatever trivial workarounds, so I don't particularly think it's a good idea. For the challenge itself, I don't know if it'll be well-received either. (For the record, BaNaNa = Barium Sodium Sodium = atomic number 56 11 11.) – Bubbler Sep 7 '20 at 3:37
• Since this is such a short string composed only of letters, it's very, very simple to work around it. You need a better restriction method. See this, and the questions in restricted-source – Razetime Sep 7 '20 at 4:24
• Indexing into custom character sets will make this trivial. – Adám Sep 7 '20 at 5:03
• JS, 11 bytes: Ba\${+"a"}a – Redwolf Programs Sep 7 '20 at 14:44

# Find the nth positive integer m for which $$\\tan(m) > m\$$code-golfmath

Write a program/function that when given an integer $$\n\$$ as input outputs the $$\n\$$th positive integer $$\m\$$ for which $$\\tan(m) \gt m\$$.

Note: $$\m\$$ is in radians

## Scoring

This is so shortest bytes wins.

## Sample Testcases

# n -> m
1   -> 1
2   -> 260515
3   -> 37362253
5   -> 534483448
9   -> 214112296674652
10  -> 642336890023956
16  -> 4285797387061825747646013

Find more at A249836

Inspired by What is the biggest tangent of a prime?

• +1 for referencing a MegaFavNumbers video. – Razetime Aug 20 '20 at 3:24
• I don't understand the point. Are you asking us to find the nth number such that tan(x) > x? Is there any approach that will be shorter than iterating over all numbers until you find the nth number such that tan(x) > x? – the default. Aug 20 '20 at 3:33
• Where is n in the equation? I'm lost. – V. Courtois Aug 20 '20 at 9:07
• @Razetime On the channel Stand-up Maths, right? – Rosie F Aug 20 '20 at 18:49
• replace "nth" with "first" "second" etc -> "first/second/etc number m for which ..." i.e. n is not in the equation @V.Courtois – golf69 Aug 20 '20 at 20:30
• @Mukundan314 maybe indicate that n is the input? – golf69 Aug 20 '20 at 20:31
• @golf69 oh! So it has to be an integer, not a number. I see now :) And yes, indicating n is the input would be nice. – V. Courtois Aug 21 '20 at 6:50
• I don't really see this being solved any way that taking the generic golfiest code for "find the n'th number meeting [predicate]", of which there's plenty of challenges, and sticking in tan(m)>m for the predicate. – xnor Aug 22 '20 at 7:04
• Solutions relying on floating-point arithmetic will get the wrong answer starting around the 11th term. You’ll need to clarify whether that’s acceptable. – Anders Kaseorg Aug 22 '20 at 22:14

# Is it a Pythagorean triple? code-golfdecision-problemgeometrymathnumber-theory

Given three numbers, determine whether they form a primitive Pythagorean triple. Here is the definition:

• all three numbers are positive integers
• they represent the side lengths of a right-angled triangle, that is, $$\a^2 + b^2 = c^2\$$ for any ordering of $$\a\$$, $$\b\$$, and $$\c\$$
• no other primitive Pythagorean triple exists with the same ratio of side lengths, that is, they are coprime. For example, $$\[6, 8, 10]\$$ is not a primitive Pythagorean triple, even though it satisfies the above conditions, because the simper $$\[3, 4, 5]\$$ exists.

## Rules

• Unless your language doesn't support them, you must accept floating-point numbers (even though Pythagorean Triples use, by definition, integers)
• meta: Is this necessary? Is it too restrictive?
• You may be given negative numbers, $$\0\$$, or numbers that cannot form any triangle (right-angled or not, i.e. $$\a + b \le c\$$), in which cases you must return false.
• meta: Is this necessary? Does it make it too difficult?
• You can return any two distinct individual values, or any typical truthy/falsey values for your language.
• Standard I/O and loophole rules apply.
• This is , so shortest function or full program in bytes wins.

## Test Cases

[0, 3, 3] => false
[3, 4, 5] => true
[5, 3, 4] => true
[3, 4, 6] => false
[3, 4, 10] => false
[6, 8, 10] => false
[3.0, 4.0, 5.0] => true
[3.1, 4.0, 5.0] => false
[-3, -4, -5] => false
[3, 4, -5] => false
[4.5, 6, 7.5] => false
[91, 60, 109] => true
[264, 265, 23] => true
[81, 210, 184] => false
[140, 221, 83] => false

## Meta

• Are the first two rules necessary, or do they restrict it too much?
• Is it clear enough? Are there any additional rules I need to add? Are more test cases needed?
• Does this suit the and tags? It's kind of tangential to both areas.
• Is this too similar to the existing questions that want you to generate triples?
• possible duplicate of this challenge – Razetime Oct 18 '20 at 13:38
• @Razetime that challenge appeared on the front page today and inspired me to make this one. I thought it was different enough because of the coprime requirement and I added the extra rules about invalid values/floats to make it more interesting as well – pxeger Oct 18 '20 at 14:32
• Input validation tends to make for a challenge that is less fun. The coprime requirement is nice, but I'm not sure if it completely changes the challenge. – Razetime Oct 18 '20 at 15:04
• This seems to me to be too much a combination of two separate generic tasks, checking that a^2+b^2=c^2 when sorted, and that a and b are relatively prime. – xnor Oct 19 '20 at 9:40

# Am I A Perfect Two Integer?

A “perfect two integer” is an integer that works as x in the following equations:

Let i = integer, j = integer, x = perfect two integer:
2^i = x
j^2 = x

Example “perfect two integers”: 4, 16, 64, 256, 1024 (see a pattern here?)

Your answer should take a number from stdin or an argument. This should be relatively easy, but this is , so the shortest answer wins. (Note: there are ways to simplify these equations that aren’t listed here).

## Sandbox Questions:

1. Is this a duplicate?
2. Is this too easy?
3. Any other thoughts?
• My personal feeling is that this is too easy. There's not really much scope for golfing the answer once you find the pattern. – Sisyphus Oct 28 '20 at 0:25
• Yeah, you're probably right. It's kind of just like if it's a power of 4. I somehow didn't think about this while making the question. – nthnchu Oct 28 '20 at 0:34

Find out if a function returns its input.

# Input Format

Input is a math expression as a string with operators + - * /. Whitespace can be ignored. For more info, check the examples.

# Example Input/Output

Input: n /3 + 2*n/3 + 175 - 175x(n+ 1-n)
Output: true
Explain: Simplifies to "n".

Input: f
Output: true
Explain: Any variable is allowed.

Input: j*(j-3)/(j-   3)
Output: false
Explain: When j is 3, evaluates to an error.

Input: 1j
Output: anything or error
Explain: Use "1*j".

# Scoring

This is , so lowest amount of bytes wins!

## Sandbox Questions

I posted because of reputation limit, but was too unclear, any suggestions please?

• There's some inconsistency in the examples: the first one is being treated as if it's a maths expression whereas the third one is not. Suppose the input is n/2 + n/2. Should the output be true? In some languages the output will not necessarily be the same as the input: / might get you floor division or conversion to a float. You can avoid these issues by treating the input as maths. But in that case, example 3 should simplify to j. – Dingus Jan 5 at 9:38

# Undecidable halting set

Write a program such that the set of natural numbers on which it halts is not recursive.

Shorter is better.

You may assume natural numbers in your language are unbounded.

## Example: Python 3 (52 chars)

lambda n:eval(n.to_bytes(n.bit_length()//8+1,'big'))
• This boils down to "emulate a Turing-complete language", which is the same as eval in any Turing-complete language that supports the feature (as you already showed in the example). I don't think it's an interesting challenge. – Bubbler Jan 19 at 6:37
• @Bubbler Eval is only half the battle (assuming the language has eval in the first place). You still need to handle the fact that the inputs are natural numbers, not arbitrary strings. That is, you need to surject the natural numbers onto a set of strings sufficient to get the undecidable behavior under eval. – user76284 Jan 19 at 7:08
• @Bubbler I'd consider an eval-free version of the challenge though, if you have any suggestions. Not sure how that restriction is usually phrased/enforced. – user76284 Jan 19 at 7:09
• Eval is half of the battle, but the other half is converting a natural number to a string, which is just a matter of base conversion (which gives ALL strings, maybe except strings starting with null bytes, which doesn't matter in most languages). Unfortunately, banning built-ins is discouraged, and we already had a challenge about simulating a different Turing-complete language, so I don't think banning eval will make the challenge better. – Bubbler Jan 19 at 7:36
• @Bubbler Is banning eval not an objective restricted-source criterion, as opposed to “no built-ins”? – user76284 Jan 19 at 19:28
• Banning built-ins means banning a specific feature of a language, like some old challenge banned exponentiation. It is different from restricted source, which is about restrictions in the source code as text, not looking at the features it uses. There are various classes of eval, e.g. interpret the whole language (Python's exec), interpret the subset of the language (Python's eval and ast.literal_eval), interpret a different language (you can't even count how many Turing-complete mini languages are out there; if Perl regex is Turing-complete, would you ban it?), etc. – Bubbler Jan 21 at 0:53

Here is the problem, for which I can only think of an iterative solution and have not found a closed formula.

This problem was found on : https://www.codingame.com/ in the shortest codemode.

You need to paint a house with R rooms.

For each room there are four walls and one ceiling, which all have the same dimensions and need C coats of paint.

You can't paint the next coat until the previous one has dried. You're finished when every wall is dry. Time taken to move between walls, ceilings, rooms is negligible.

It takes you M1 minutes to paint each coat, and M2 minutes for the paint to dry on each. You must finish in the least possible time, otherwise they will not pay you.

NOTE DON'T FORGET, THE PAINT MUST ALL BE DRY BEFORE YOU CAN RECEIVE YOUR PAYMENT!

In :

Line 1: R, C, M1, M2 separated by spaces.
R: Number of rooms in the house
C: Coats of paint needed for each wall/ceiling
M1: Minutes taken to paint each coat
M2: Minutes taken for paint to dry on each coat (measured from when you've finished the entire coat)

Out :

The time taken to paint the entire house in the format H:MM

Contraints

1 ≤ R ≤ 10
1 ≤ C ≤ 20
1 ≤ M1 ≤ 10000
1 ≤ M2 ≤ 10000

Dataset:

input: 1 1 12 0

output: 60

input: 5 2 5 30

output: 280

input: 1 5 5 200

output: 1045

• Is this a problem from another site? If so, you need to state where the problem comes from. Also, unlike other online judge sites, we tend to allow submissions to be functions or full programs, and allow a wide range of I/O methods for both. Having to convert the minutes to hours/minutes and format as h:mm is not so related to the core (and requiring such formatting is discouraged on our site), so I suggest to simply output a number in minutes. – Bubbler Jan 28 at 0:16
• @Bubbler I have taken your remarks into consideration. I hope it's what you expected. – Simon Rochwerg Jan 28 at 9:31
• Do you have permission to repost this challenge? CodinGame's rules state (Article 9): 'The reproduction, representation or use of all or part of the components proposed in the CodinGame Contests is strictly prohibited.' – Dingus Jan 28 at 12:15
• Posting a challenge from elsewhere so that you can be shown an answer is engaging with this community in bad faith. You can ask for programming help in places such as SO, but this isn't intended to be one of them. – xnor Jan 28 at 17:05
• @xnor I am not acting in bad faith or such. I found this problem interesting and I wanted to share with the community to find an optimal answser. There is nothing for me it this except extending my own knowledge as well as community knowledge – Simon Rochwerg Jan 29 at 9:00

# Hello World! - Generation 3392

Your job is to create a genetic algorithm that slowly evolves and mutates its string until the output is equivalent to "Hello World!".

The genetic algorithm should start with a random string generated, and continue for generations, making random mutations to its code, like this:

Gen 3393 - Hemmo World!

To:

Gen 3394 - Hemko World!

# Heres how the randomization algorithm works:

1. Create a function named randint(n), import the time module.
# Written in Python 3.8
import time # imports time
def randint(n): # create function
1. Get the current time since Jan 1. 1970, multiply by n and assign it as var "t". Make t an integer not a float.
t=int(time.time()*n) # Set time, and multiply by n.
1. Use the "%" operation on var "t" (var t is the first argument), with var n as the second argument, assign it as "rand". Code in python should look like this:
rand=t%n #setup a psuedorandom number, since you already have a counter, use n as the limit number, and reset the counter once the counter reaches the limit number. This generates a psuedorandom number within n.
1. Return rand.
return int(rand) #return results as integer.

• A randomized start string (using the rand_int algorithm)
• A point it reaches "Hello World!"
• Mutation, using "parents". You are not allowed to completely change a string, only modify 1 character each generation.
• Mutations are not allowed to be repeated twice/No mutation backtracking.
• Once a genetic algorithm has a correct letter in its correct position (such as "e" in "reJ" and "Hes"). It is forced to stay as that letter in that position and the genetic algorithm is forced with that string forever, this repeats for all other positions. This way the time increases additionally instead of exponentially. So you cannot do this: ["Hlllr" -> "Hellr" -> "Hfllr"]

So I can do this:

Herlo Wcrld
Herlo Wrrld

But you cannot change >1 character/byte at a time:

Herto Wcrld
Heflo World

You can do whatever else you want with it if it satisfies those requirements.

# Scoring:

This is , so the answer with the least amount of bytes wins.

• For code golf to work, the rules must be very clearly defined. At the current state people will do do (s:=randomString()); while(s!="Hello world!"); print(s); (pseudocode): (you can make this a popularity contest, but that's even harder to get right. I don't know why) – user202729 Feb 6 at 13:46
• @user202729 I want the person to make a genetic algorithm, where it starts with a random string. mutates the previous string randomly by 1 character during each generation, and eventually outputs "Hello World!" – fr4cew Feb 6 at 13:55
• Besides being poorly-defined, it is also an non-observable behavior. – user202729 Feb 6 at 14:02
• No, (hey, that's a link. Read it.) – user202729 Feb 6 at 14:09
• Wait, that's not what I mean. I'll explain it later. – user202729 Feb 6 at 14:47
• @user202729 Right... – fr4cew Feb 6 at 14:53
• But if the mutations between generations are random, there's no guarantee that the program will ever generate a specific string. You have to add a constraint like "the program should not generate a given string twice" – Sheik Yerbouti Feb 6 at 17:11
• @Davide I think that rule already existed in the "A point it reaches 'Hello World!'" but I'll add that anyway. – fr4cew Feb 6 at 19:26
• A few things that I find missing from the rules: How long is the string? How do you mutate space/punctuation marks? I agree that is has non-observable behavior, because you can't see it mutating the string. Does the code have to be in python? Why should it randomize its input and why should it be random during the process? Wouldn't it be better if you get a string from user input (defined length) and then transform it to "Hello World!" (because that would allow bf and other languages to work) – Deadbeef Feb 7 at 6:37
• @Deadbeef 1. The length of hello world, 2. It works with base 64, 3. No, 4. Because I liked it that way. 5. I do not know. – fr4cew Feb 7 at 15:22
• Okay, about the unobservable behavior, what I mean is... – user202729 Feb 7 at 15:59
• It's relatively hard to define what exactly "having a string stored internally" means (what if the string is stored as a list of int values (char codes)? What about encoded in the exponent like in FRACTRAN?) Instead, you can require the programs to output the generations (i.e., print the random strings, each subsequent string has one character changed, etc.) [please review other sandbox posts] – user202729 Feb 7 at 16:02

# Return all elements around an index forming sun

Define a function that takes in a 2D array and a 2D index, and return all the elements of the 2D array that are directly vertical to, horizontal to, and diagonal to the given index, and the returned list must omit the index itself.

External modules, like numpy, as allowed. The most efficient program wins.

• ... while we do have [fastest-code] on this site, there are specific requirements; restricting allowed programming languages is another problematic thing; – user202729 Feb 8 at 14:38
• besides, this definitely sounds like that you're outsourcing your homework to this site. – user202729 Feb 8 at 14:38
• @user202729 I already have a numpy solution... this is definitely not homework XD – Accept one day later Feb 8 at 15:34
• @user202729 Okay, removed language restriction. – Accept one day later Feb 8 at 15:35
• Okay, the other problem is with "most efficient code win". Code golf is popular around here because it's easy to measure, but with this you have to install all sort of weird programming languages on a test machine. – user202729 Feb 9 at 2:07
• I don't think this is very interesting to do fastest code anyway, because it can be done in linear time anyway (with the array given); besides the general consensus is to allow "full program or function" [please review other sandbox posts] – user202729 Feb 9 at 2:11
• @user202729 Okey. – Accept one day later Feb 9 at 2:27

# Create a Screw

There are a variety of code cad languages, as well as other 3d API's that allow you to define shapes with code. Some of these are limited, while others are Turing complete and/or use a popular programming language such as Python or JavaScript.

# The Challenge

Output a 3d model of a screw. Acceptable formats include .stl files and .obj files. A screw is defined as a shorter, wider cylinder on top of a taller, thinner cylinder, which should be threaded at least 5 times. Winner is whoever has the shortest code by two weeks after this question is posted. Standard rules and loopholes apply, with the exception that anything that allows you to programmatically define a 3d object is treated as a program language.

# Changes

Should I add a spot for the screw driver to my definition of a screw? On the one hand, that would be more realistic, but on the other, it might just add bloat to answers, since I don't think there's anything interesting you can do with it.

I plan to include an example of a minimal screw under whatever definition I end up using, with pictures and outputs in every allowed format.

For the purpose of sorting and answer headers, should each langauge/framework combo be treated as a separate language? I'm leaning towards this, since It would be cool to have an easily searchable set of code for a bunch of different frameworks.

• While the challenge is probably clearly defined enough, it might not allow solutions more interesting than hardcoding compressed output. – user202729 Feb 15 at 2:04
• How could I make sure that it does without fundamentally changing it? Or do you think that's not possible? I feel like there might be some potential for interesting ways of doing the threading, but I haven't used very many of these languages.. – import huh Feb 15 at 2:40
• No idea... I think that (1) if there's a lot of boilerplate in the file format, using a library might be shorter (2) if the structure of the output file is not very repetitive, computing the coordinates might be shorter than hard coding + compressing it. I'm not familiar with either file format so I can't tell. -- -- nevertheless the challenge is on-topic; what I've said only concerns whether it's interesting [please review other sandbox posts] – user202729 Feb 15 at 2:46
• I think both formats basically just contain the points for every triangle used to represent the 3d object. To be honest I didn't really think about directly creating the file. Compared to using a library, it seems incredibly inefficient. That could make for an interesting challenge on it's own, though... – import huh Feb 15 at 2:58
• You should probably add a specific diagram with the proportions for the screw, or maybe ask the program to take it as input – Razetime Feb 15 at 2:58
• @Razetime There's no specific proportion, just "larger" and "smaller". – user202729 Feb 15 at 3:06

This is a graphical output question.

Standard loopholes apply, connections only allowed to codegolf.stackexchange.com

One language can be only used once, but a user can post multiple answers in different language

• This is probably a dupe of this. Finding the avatar instead of the id wouldn't affect most of the code. Your final line is odd, do you mean that if I answered in a language it would prevent anyone else from using that language? That seems like a bad rule - what if I started on my answer and someone posted while I was working? I can't see any benefit, but perhaps I am not understanding. – FryAmTheEggman Feb 20 at 18:10
• I think it would be interesting if you have to print the ascii representation of the user before you , without scraping. With a standard way to produce the ascii image so people can't differ. i.e. img to ascii – Alex bries Feb 20 at 21:13

See who can write the longest code in order to print "Hello World!". The rule is that if you remove any single character from the code, it should NOT run.

• I think we have a similar challenge already. It's pretty easy to get an infinite score with these rules. – Redwolf Programs Feb 25 at 1:23
• It is a weaker version of Programming in a Pristine World and a different variant of Biggest Irreducible Hello World. But note that, in many languages, it is possible to add arbitrarily long no-op code that breaks when exactly one char is removed. For example, Python's ''+''+''+... causes syntax error when any of ' or + or a newline surrounding it is removed. – Bubbler Feb 25 at 1:41

# Output function from one to another

I tried to post this twice and I gained negative feedback, so I will put what I have in mind here if anyone is interested.

Get a certain output function from one programming language and transfer to another. You'll be recreating an output function that came from a different programming language. There is a certain criteria in order for the answer to be valid:

1. It should function the same way as the original function. All things that function can do should be applied to the recreated one. For example, Python's print() has certain keywords like end.
2. Syntax doesn't matter. Example, if you can't use the << for cout, don't use it. Use what's available.
3. The function should be able to output the same errors like the original. Replicate the same errors from the original function. If impossible, leave it out.

An answer example would be making printf() from C using Python or making Console.WriteLine() (or just WriteLine() if incapable) from C# using Ruby. Any output functions that are already similar to 2 languages don't need to be replicated in any of them.

• "Get a certain output function from one programming language and transfer to another." To clarify, is the challenge to write source code which works in two different languages and does the same thing? What's the winning condition because this sounds very trivial. For example, print does the same thing in many languages. – 79037662 Feb 24 at 20:25
• Actually that doesn't mesh with "syntax doesn't matter". The point of this challenge is completely unclear, could you please clarify it? – 79037662 Feb 24 at 20:26
• I see you edited this post but the point of the challenge is still completely unclear. What exactly would a valid submission look like? – 79037662 Feb 25 at 20:56
• I don't really get the point of this task. Sure, someone could write code that does this, it might take some work to get exactly right, but is there a challenge underneath it? Is it code golf? – xnor Feb 26 at 3:08
• @xnor It isn't code golf, nor king of the hill. It's an ordinary coding challenge if they can replicate a function from one language to another. – Mark Giraffe Feb 26 at 5:53
• @MarkGiraffe That's not really a thing on this site -- challenges need to have an objective winning criterion. From the close reason: "Questions without an objective primary winning criterion are off-topic, as they make it impossible to indisputably decide which entry should win." – xnor Feb 26 at 8:13

# Random Roman Numerals

Printing a random number is easy, but what about roman numerals? Your task is to output a random roman numeral from 1 to 1000, both inclusive.

Requirements:

• Each number has to have the same chance of appearing
• The program should use the language's random module or other random algorithm

Remember, I is 1, II is 2, III is 3. V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. Also note that IV is 4, IX is 9, XL is 40, XC is 90, CD is 400, and CM is 900. For more information see the Wikipedia page.

This challenge is , so try to have the shortest program possible!

• I'd really recommend loosening the restrictions for the random numbers. What if the language's random module doesn't guarantee exactly equal chances? Can we assume it does? What about an implementation of an algorithm typically used by language's random modules, like xorshiro or the mersenne twister? A much better restriction in my opinion would be requiring that every result is possible, and it's unlikely people will deviate too far from a uniform distribution anyway. – Redwolf Programs Mar 10 at 5:43
• Sounds like you're combining two or more unrelated core challenges into one ― consider splitting the challenge up into separate challenges ― or dropping unnecessary parts. Just watch out for duplicate challenges: random number generation and Roman numeral conversion are popular tasks. – Adám Mar 10 at 6:01

# Is this an one-one function?

Two sets given as input, one is the domain of a function, and other one is the co-domain of a function. As an example

$$\{1,2,3,4\}$$ $$\{5,6,7,8,9\}$$

Now if the range set of the function, i.e. set of each element in the co-domain set which maps to the domain set (1 -> 5, 2 -> 6, ......) is equal to the co-domain set, then it is a one-one function.

For the above example, the range set is

$$\{5,6,7,8\}$$

So the range set is not equal to co-domain set, the function is not a one-one function.

# Challenge

Inputted two domain and co-domain set of function, output a truthy value if the function is one-one or falsey if not.

# Test cases

{1,2,3,4} {5,6,7,8,9} -> Falsey
{a,b,c} {b,c,d} -> Truthy
{4,8,2} {3,4} -> Falsey

Standard loopholes apply, , so shortest code wins

Pre-defining the input sets in the header section of TIO is not allowed.

• Is this challenge simply asking if the two sets have equal length? If not, can you include counterexamples? – water_ghosts Mar 21 at 18:03
• @water_ghosts yes i feel it is like that – Wasif Mar 22 at 5:14
• not particularly interesting – rak1507 Mar 22 at 12:11

# Remaking Kernel code-golf

I made a program as a final project in the main CS50 Harvard course, and it was named Kernel, written in C alsongside CS50's library.

## Functions

It has 7 functions: 4 main (talk, count, calculate, build) and 3 advice functions (error, feedback, help).

What each function does:

• Talk asks for a prompt to the user and outputs the same thing.
• Count asks for a number to count from 1 to there. If the number is bigger than 50, it will lead to an error.
• Calculate asks for 2 numbers and an operator (must be either +, -, * or /) then will calculate the value. If the result is a number is greater or equal to 999999999, it leads to an error. However, 0 / 0 = 0 and other division rules still apply.
• Build asks for a size and something that it can build, which could be either a line, tower, wall, or pyramid. If the size is more than 20, it leads to an error. It would then ask for the character you want to use to build it, then it will be used to build the final product. There are multiple errors here, which is explained at the Error function.
Disappointed that I can't make a proper pyramid.
• Error is a library that shows all 14 errors, which is listed in the Error page of this post.
• Feedback asks for feedback from the user and they can type whatever they want. The input will then be transferred in a new file called Feedback.list.

Inside Feedback.list:

• Help displays the info of the entire app.

## Errors

There are 14 written errors to prevent writing the real errors.

1. NO_FUNCTION_ADDED: When asking for which function to use, entering a non-existent one will result to this error.
2. ERROR_CLASS_NONE: In Error, entering a number which doesn't have its error will pop this up.
3. COUNT_MAX: Well, typing a number greater than 50 won't put up the error, but counting up to 50 will.
4. INVALID_DIVIDE: Anything divided by 0 in Calculate (except 0 / 0) will put up this error.
5. ExTREME_VALUE: In Calculate, earning a final number of 999,999,999 or more will result to this error.
6. OVERSIZE_CHUNK: Entering a size larger than 20 in Build will result to this error.
7. UNKNOWN_STRUCTURE: Also in Build, inputting a structure unavailable will pop this up.
8. UNCLEAR_INSTRUCT: If the input for Build's line is not vertical, horizontal or diagonal, they wouldn't know what it is.
9. OVERWIDTH_COUNT: Building a tower with a width of 20 or more is invalid.
10. INVALID_PYRAMID: Similar to Build's line, inputting a pyramid unavailable pops this up.
11. OPERATE_BAD: Inputting an operator unavailable in Calculate is invalid.
12. MORE_NAMES: If you didn't know, to run Kernel, you need to add your name alongside running it. Me, I use ./Kernel MarkGiraffe. If I use Mark Giraffe instead, it is invalid.
13. SECRET_USER: Even NOT putting a name is not allowed.
14. BAD_ALIGNMENT: Not choosing left or right for a diagonal line in Build is invalid.

For this challenge, I want you to remake the program the most designed way, while still keeping low bytes.

In case you are interested, I will post the source code somewhere where you can view it.

• This has LOTS of quality issues. 1) Being a multipart challenge with unrelated subtasks. 2) Rigid I/O (command line arguments AND interactive stdin/stdout AND file output). 3) Input validation and error handling in arbitrary ways. 4) Lack of specification in certain cases. 5) Putting I/O examples in images instead of code blocks. – Bubbler Mar 23 at 4:10
• I think the outstanding question is, why would people want to code and golf here? Like, it's cool that you wrote a thing, but it seems like a lot of work for someone to re-do on a recreational programming site without a really compelling reason. – xnor Mar 26 at 3:29

Given a program as input. If the program ever output a '1', output a truthy value and halt; if it halts without ever outputting a '1', output a falsy value and halt; if it falls into infinite loop without outputting a '1', fall into infinite loop.

• This is unclear, for example: what language will the program be in? Do we take it as a string? And for a turing-complete language, this is impossible (at least if it can take input). – Wzl Apr 2 at 15:45
• @Wezl Why not?? – l4m2 Apr 2 at 16:09
• You didn't specify the above ^ points, which are important. – Wzl Apr 2 at 16:17

# Poly-functional Polyglots

I don't have a ton of time to work on this, so I decided to remove it temporarily while I rework the scoring.

• I think the scoring system is too convoluted. Optimizing for the bonuses seems like more of a challenge than completing the core task. And if number of languages is the denominator, it’s hard to know how to calculate that upfront. How many shells does echo “Hello World” work in? If I later learn about another one, does that retroactively lower my score? – water_ghosts Apr 2 at 16:53
• @water_ghosts thanks for saying so. I was worried that that would be the case, especially after reading the discussion on things to avoid in questions. I'm going to try and rework this. – Aaron Miller Apr 8 at 19:26

# Generate a Printing Program In Some Language

Given some rules:

1: Hello
2: World
4: Code
7: Golf
9: Whatever

Your program should output a program or a function (the output), which should be a valid program (or function) in some language. When the output is run, it should

1. Ask for some input (i),
2. Then output the string in the ith index in rules. (If there are none, don't output anything - even an error.)

### Example:

Rules:

1: Hello
5: World
19: Code

One possible output (python):

while True:
i = int(input())
if i == 1:
print("Hello")
if i == 5:
print("World")
if i == 19:
print("Code")

## Scoring

Obviously this question should be clarified.

• Can we take input as an array of rules (2d, like [[1, "hello"], [2, "weijfiwef"]])? If the index is not in the rules list, can we output an empty string? – Recursive Co. May 16 at 7:42
• Well I thought about that, but some strong-type languages don't allow different types in a same array. If the index is not in the rules list, you can't output anything (as said in step 2). – SketchySketch May 16 at 8:33
• Is my output required to be a full program or it is allowed to be a function? – tsh May 17 at 7:21
• Yes @tsh, can be either full program or function. – SketchySketch May 17 at 14:09
• Why downvotes? Could you please explain why? I'll improve – SketchySketch May 17 at 14:19
• @SketchySketch Not a downvoter, but it seems to be a boring challenge. – Xwtek May 20 at 9:18

Given two reals $$\a\$$ and $$\b\$$, output some reals $$\r_i\$$, such that $$\\sum r_i=a\$$ and $$\\prod\left(r_i+1\right)=b\$$. You can assume that it's possible. You can also assume that your float type have infinite precision.

Test cases:

2,3 => 2 or etc.
2,4 => 1,1 or 1/2,(sqrt(57)+9)/12,(9-sqrt(57))/12 or etc.
2,5 => 1/3,1/2,2/3,1/2,0 or etc.
2,8 => sqrt(17)+2,2-sqrt(17),-2 or etc.
2,2 => sqrt(2)+1,1-sqrt(2) or etc.
e,2e => 1,e-1 or etc. (e is natural base, though any number>1 work)
-4,9 => -2,-2 or etc.
0,-1 => sqrt(2),-sqrt(2) or etc.

Shortest code wins.

# Notes

• Though I only removed two positives from the existing question, it's a huge change to the result.
• I decide to keep the assume possible part just to make the note above correct. It can actually be proven that it's always possible.

# Breaking BogoBogoSort (In Badness) code-golfmatharray-manipulationcombinatoricsrandom

The title says it all - make a sorting algorithm with a time complexity of $$\O(n!^{n!})\$$ or higher in the fewest bytes possible - as far as I can tell, that will require you to make a double exponentiatial formula or worse: that is, $$\O(a^{b^n})\$$, where $$\a, b > 1\$$.

# Rules (since there must be some)

The list must be returned sorted in a finite time. This can be as high or as low as you want.

The algorithm must work for any real numbers (-30% if you can sort any single type given it's non-mixed).

The algorithm must work of any list length, and must eventually outpace ALL $$\O(n!^{n!})\$$ formulas, not just BogoBogoSort, and you must state the exact $$\O\$$ growth rate (for example, $$\O(2^{3^n})\$$). It may start off slow, but must eventually outpace all other expo-factorial functions (as I now name this growth rate).

Shortest code wins.

• What prevents someone from doing a loop just to make it slower (or calculating $n!!!!$, etc.), and then just sorting the array with quicksort? – Command Master Jun 5 at 8:00
• Logic. Logic prevents them from doing something that the question didn't mean you to do. Standart loopholes are forbidden by default – LeopardL GD Jun 7 at 8:25

# I am not a dad!

Given a non-empty string. Check if it starts with "I am"/"I'm" (case-insensitive) and if it is, output the dad joke. Otherwise, terminate
P.S. There must be nothing in the STDERR.

# Examples:

"I am an idiot" -> "Hi an idiot, I am Dad"
"I am rewuytheruty" -> "Hi rewuytheruty, I am Dad"
"i Am case insensitive" -> "Hi case insensitive, I am Dad"
"I'm A" -> "Hi A, I am Dad"
"i'M B" -> "Hi B, I am Dad"
"Iam together" -> terminated
"Nothing here!" -> terminated

# Rules

• This is , so the answer with shortest bytes wins.
• These loopholes are, obviously, forbidden.
• Standard code-golf rules apply.
• Please specify the language you are using and the amount of bytes.
• It would be great if you would put a link to a sandbox where your code can be ran in action, such as TIO.
• Explaining your code is very welcomed.
New contributor
LeopardL GD is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
• I don't think the exceptions add anything to this challenge to be honest. And if you do keep them, they need to be better specified. – pxeger Jun 13 at 19:38
• Input validation is frowned upon (validation to check if any of the exceptions appear). As well as that, I observed that there are virtually no patterns or magic bitwise operations that can handle them, just hard-coding a few extra strings and some ternary operators. Doesn't really add anything to the other dad joke challenge to be honest. – Recursive Co. Jun 14 at 12:19
• And if I would remove the exceptions, will the challenge become better? Will it be worthy publishing? – LeopardL GD Jun 14 at 12:52

# Every number is interesting

We know that every number is interesting but how?

You should write a program or function which:

• takes a list of N positive integers (>0 and <2^31)
• outputs N lines each of them showing how the corresponding input number is interesting
• is not longer than 1024 bytes
• uses no more than 1 second per number
• doesn't use external sources

## Examples

172: 444 in base6
5776: 76*76
9801: 9 * 1089 (reverse)
68101: no 11 in base2 (10000101000000101)
491033: 317 * 1549 (product of 2 big primes)
467808816: no digit 5 from base6 to base10

## Inputs

You should include the output for the following input in your post:

58 92 120 224 358 490 912 1578 7812 222008 1645060 19796411 550453633

If you care to run your program on a bigger sample and share the result with us use this input data (2500 numbers). (You can upload your output to e.g. pastebin.)

This is a popularity-contest so highest voted answer wins.

Tags: popularity-contest, number

• What sort of criteria are necessary for defining a number as 'interesting'? I see things like square numbers, other bases, etc. But are there any specifics? I'm interested in this challenge (but worried it might be closed as too broad). – ASCIIThenANSI Apr 7 '15 at 13:18
• @ASCIIThenANSI There wasn't a clear definition. That's part of the reason why I abandoned the challenge. – randomra Apr 8 '15 at 1:55
• Would you mind if I tried taking it up? I would have to post as a new answer, because I can't directly edit. – ASCIIThenANSI Apr 8 '15 at 2:00
• @ASCIIThenANSI Not at all. – randomra Apr 8 '15 at 2:01
• @ASCIIThenANSI Where did you post it? – wizzwizz4 Jul 24 '19 at 13:33
• @ASCIIThenANSI I am also curious – MilkyWay90 Aug 27 '19 at 23:41

# Create a Drawing Guide for a Polygram

Poor old Jim, he's just terrible at drawing polygrams, and he's asked you to create a "drawing guide" for him - an ascii polygram with numbered edges, so he can follow the instructions.

## Challenge

Write a program to produce an ascii polygram with P <= 10; each edge of the polygram should be made of a single digit 0-9, showing the order in which the edges should be drawn.

## Input

Your program should receive (via STDIN, as function arguments, or some other language-appropriate method): P, the number of edges/vertices of the polygram, and Q, the spacing. In the notation as per the Wikipedia link, you'll be drawing a {p/q} polygram.

## Output

Either print to STDOUT or return (or something else language-appropriate) a multiline string showing the drawing guide for the given polygram. The string can be any size you like, as long as it's large enough to display a clear polygram.

## Notes

Your code should be able to handle compound regular polygons as well as regular regular polygons, and also inputs of q > p/2 (poor old Jim doesn't realize that the polygram for {p/q} is the same as for {p/p-q}).

## Example Output for {10,3}

5
5 4
4
21     5        888
2 11115     8888  7
2    5111888 4    7
2     888111  4   7
2  888      111   7
8885           4117
8882               4 711
8   2 5               7  111
25               47
9   5                 7    0
9  2                 74  0
52                 7  0
9 2                 7 4
5 92                 7 04
9                 70  4
5   2                 7
5    29                7    4
6666 2 9              07   33
666              0 7333
2 696           337
2   9666     333  7
2    9  66633 0   7
2      333 666    7
2   339       666 7
2333   9    0    67
9  0
0

## Scoring

This is code-golf, so shortest in bytes wins. Tiebreaker goes to the most votes.

• I have a python solution to this which is ~600 bytes, so it's definitely doable, and it's not easy... – sirpercival Apr 27 '15 at 4:31
• I think the spec needs to be more prescriptive for this to make a good question, especially since the example seems to indicate that you're not currently even prohibiting the lines from having gaps. At a minimum I would say that you should require the lines to be equivalent to those produced by Bresenham's algorithm, and specify how overlaps should be handled; at the extreme, you could tie it down so tightly that it becomes a parameterised kolmogorov-complexity. – Peter Taylor Apr 27 '15 at 9:34

# Pointer to pointers to pointers to pointers

You should choose a language supporting pointers like C. And your task is simple: demonstrate a legitimate use of the most level of pointers.

You should justify your code by describing an algorithm that:

• Has only plain text, number or an array of those as input and output.
• You think it will make things easier to write those code as a part of the implementation of this algorithm.
• This implementation would have optimum memory usage (only declared variables and parameters, explicitly allocated space, and the return addresses for recursive functions count).

Other rules:

• They must be pointers to pointers directly, i.e. a pointer to an object containing a pointer doesn't count. It's better if nobody using this code will want to extend some pointer to an object later.
• Each pointer must have a different type (if your language can somehow make them the same type).
• You should create at least one pointer, and either dereference or compare two non-null pointers once in each level.
• Using pointers as arrays is only half as interesting.
• Iterators, etc, are considered in essence pointers and allowed in this challenge. But you can't define new types implementing iterators for this purpose.

• Could you specify "legitimate"? This sounds a bit like code bowling (and seems to have the same issues). With enough imagination I'm sure I can justify any depth of pointers. – Martin Ender Apr 30 '15 at 17:43
• @MartinBüttner Edited but, basically, it is subjective. – jimmy23013 Apr 30 '15 at 17:57
• @MartinBüttner Added a restriction to have optimum memory usage. I'm not sure whether it works. – jimmy23013 Apr 30 '15 at 18:19