Sandbox for Proposed Challenges

Question

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

Sandbox FAQ

Posting

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

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

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

Discussion

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

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

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

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

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

Other

Search the sandbox / Browse your pending proposals

The sandbox works best if you sort posts by active.

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

Answer 1

RGB to Hexadecimal

Answer 2

LS, Part 2: Sebald Code code-golfstring

WARNING: You still not gonna answer a challenge about ponies?

---

Sebald code is a code developed by Dr. Gustav Sebald purely for communication through movies. It is decoded like this:

1. We look for an instance of "ring" case-insensitive
2. Starting from the word just after the "ring" we add this to an empty string
3. We jump 11 words and add the next word after that
4. Repeat 2 and 3 until we pass one of the words "ring"
5. The string we've been adding to is the plaintext.

Note that if the string doesn't contain "ring", just return an empty string ''.

Testcases (TODO)

This is code-golf, so shortest answer wins!

Answer 3

Output your Votes code-golf internet

The challenge is simple: Print to stdout the current total score (upvotes minus downvotes) of your answer.

For obvious reasons, you do not have to include the ID of your answer in the program; you may take it from stdin or specify a place in the code where the ID must be inserted. Your program may assume that the computer it is running on has internet access and isn't restricted by SE API ratelimiting. Your program does not need to use the SE API to get the vote count, but that's probably the easiest way to do it.

This is code-golf, so shortest code wins.

Meta

Is this a dupe? I wouldn't be surprised if it is.

Answer 4

Help Santa Rest

Santa has finally delivered presents to everyone at the stroke of midnight in a day, and now he wants some well-deserved rest. He is just about to sit down when the present managing computer suddenly calls out: "ME NEED REST." Now he is asking you to write him a program that does... nothing.

You will be given command line args, you will be given STDIN input. You must swallow/ignore the input and after some length of time, quit the program. You may have no externally visible effects (other than RAM/CPU usage obviously), and the program must not hang.

Testcases

NullPointerException

Scoring

Santa wants to type this in as quickly as possible so he can rest, so this challenge is scored in bytes, as standard code-golf.

Answer 5

Print my Country

This challenge is simple: Your program must output the two-character country code of the computer it is currently being run on, according to the computer's locale settings. (Capitalization doesn't matter.) For example, were I to run your program on a computer with a location set to the United States, your program should output US. You may assume that your program is running on the latest version (Bullseye, if I'm not mistaken) of Debian Linux. This does not need to be accurate; I could easily set the locale to Antartica while being in Britain.

This is code-golf, so shortest program wins!

Answer 6

Generate 3d Christmas tree using "3d pixel art"

Imagine you are building Christmas tree from 1x1x1 sized cubes that can be attached just by sharing a side. At least one input - size, but can be more granular (height, bottom_width, etc.).

Any kind of algorithm you like, data representation should be set of 3d int vectors containing positions of each cube.

The more natural looking, the better.

If you want to visualize it too, even better. But it's not essential (I may try to visualize some of your creations).

Answer 7

Halting detector (Archived)

Choose a Turing complete language and write a program in this language that, given a program in 1TB, decide whether it halts.

Your program would likely be more than 1TB, which results in transferring difficulty¹. Therefore, you only need to show your construction and prove your code length.

Shortest code in each language win. A Turing complete language which write 2TB of program to do a loop would make short submission but that won't be fun (and I don't think such language exist now)

¹ Yeah it isn't the main point

Answer 8

Character Values Quine

Write a program that prints out a sequence of integer values corresponding to the character codes in the source code.

For example, the program:

print("Hello, World!")

has a valid corresponding integer sequence of:

112 114 105 110 116 40 34 72 101 108 108 111 44 32 87 111 114 108 100 33 34 41

Rules

• You may use a non-numerical sequence delimiter of your choice.
• The order of values in the sequence must be maintained for this challenge.
• The integers may be in any numerical base with a radix of 2 or larger. (binary or up). All the integers must have the same base.
• Code comments are permitted.
• The program may not read from its own source code.
• Standard loopholes apply.
• This is code-golf, so the shortest-length solution wins.

__

My first question, so please let me know what could/should be changed. Thanks!

Answer 9

Generate a random halting Brainfuck code

Generate a random valid halting brainfuck program using []+-<>. Every halting program should be possibly outputted.

Sandbox Notes:

• What should I add?
• Is it a duplicate?

Answer 10

Sum of numbers of arbitrary length

Answer 11

Route Planning for a delivery driver

There is a town that consists of a single long road with evenly spaced houses. Each house either needs rice, represented with a negative number, or can provide rice, represented with a positive number.

[-1, 50, -1, -1, -1, -50, 3, 1]

Here, the first house needs one grain of rice, the second can provide 50 etc.

Your delivery truck starts at the very left edge of the town, and must end on the very right edge. It has a infinite capacity, but you can't deliver if it's empty.

The sum of the input list is guaranteed to be 0.

Given a list of requirements, output the shortest possible path that can deliver to every address.

Test cases

Test Case	Output
5, -5	3
-5, 5	5
2, -5, 3	6
-1, -1, 1, 1, 1, -1	12

Answer 12

Paint you a Picture for Piet Perfection

popularity-contest

Make a Piet program that does whatever you want—but make it pretty.

Your goal is to paint a beautiful picture with an interesting function.

Your program may do anything, but your submission is much more likely to gain upvotes if it is interesting or related to the content of the picture. Likewise, your program could be incredibly interesting but look very ugly and thus receive few upvotes.

This is a popularity-contest, so the submission with the highest score wins.

---

Meta sandboxing: This might be too vague, should the program guidelines be more specific?

Answer 13

My prefix is food, my suffix is rude

My prefix is food.
My suffix is rude.
My infix comes in rounds.
I keep you off the ground.

What am I?

This is the first "Riley riddle", created by Riley. Riddles of this sort has become a trend in the Puzzling SE. Let us do a code-golf challenge equivalent of it.

The challenge is to write a program/function that expects the input to be one of three distinct values of your choice, and output what the code's prefix/suffix/infix of your choice would output, respectively.

To be more specific, the affixes shall have no input or have the input ignored, and have a constant output. For sake of preventing trivial solutions, their outputs shall be all different.

As for the full code, any input that matches none of the three values falls into don't care situation. Standard loopholes apply.

This is a code-golf, so the submission whose full code is the shortest in length wins. The lengths of the affixes won't compromise the score.

If possible, please include a poem describing what your code does, just like the original riddle! ;-)

Answer 14

Play turn-less chess

king-of-the-hill chess

---

In this challenge, you'll write a chess bot...but with a twist. Your bot can move at any time, so the faster you can think, the faster you can move. You'll write code for a custom CPU (so that precise timing is possible), and try to checkmate your opponent's king.

Rules:

• White doesn't necessarily move first; both bots get the opportunity to start moving immediately. If both bots move in the same CPU cycle, white moves first
• If a bot tries to make an impossible move (pushing a pawn into an occupied square, castling with a moved rook, etc.), the move fails, and the bot is penalized by losing a certain amount of time (or possibly the number of cycles the opponent spent on their last move)
• Instructions will cost 1 CPU cycle, with the exception of moving, which will cost a fairly large number of cycles to make rapidly moving pieces to overwhelm smart bots less overpowered
• Bots will play each other round-robin style, both as white and black. Bots will be scored using a modified Elo system (designed such that the order in which the games are played doesn't matter)

Answer 15

Minimum Buttons on a calculator to get from one number to another code-golf

My calculator looks like this:

·   ·   ·   ·   ·
  1   2   3   +
·   ·   ·   ·   ·
  4   5   6   -
·   ·   ·   ·   ·
  7   8   9   * 
·   ·   ·   ·   ·
  =       0   /  
·   ·   ·   ·   · 

Given a starting number and a ending number, calculate the minimum sequence of button presses required to get from the starting number to the ending number.

Notes:

• / is integer division, no need to handle floats
• Simple calculators always calculate from left to right, no complex order of operations
• A = is needed at the end to display the final number if the start and ending number are different

Test Cases

A	B	Result
1	1
2	3	+1=
49	33	-16=
120	1081	*9+1=

More test cases TBD

Answer 16

What is the shortest python code which implements a string-to-float function?

---

Goal

Write the shortest variadic to_float, str2float, or standardizing function you can write subject to the constraint that the code is written in python.

---

Rules and Examples

The variadic str2float shall be some callable which accepts any one of the following inputs:

Input Data-type	Example Input	Output float
string	"4.992"	float 4.992
float s	4.992	float 4.992
int	9021	float 9021.0
a shallow iterable of strings	["4", ".", "9", "9", "2"]	float 4.992
a string with zeros padded on the right and/or white-space padding on left	"1234.650000\n"	float 1234.65
a string with zeros padded on the left	"016"	float 16.0
a deeply nested iterable of strigs	[["4", [[".", "9"]], ("9", "2")], ((((("1")), "0"), "1"), "0")]	float 4.992101
a deeply nested iterable of a mix of floats, int, and strings	[[4.0, [[".", 9]], (9, "2")], (((("1")), "0"), "10")]	float 4.992101

The main assumptions about the variadic *args parameter are that there is a correctly-working method named __iter__ defined and that if you recursively search until isinstance(obj, str) returns True or not hasattr('__iter__', obj), then the object which is not a string has a __repr__ method which returns a string representation of a decimal point, integer, or floating point number.

Scoring

The scoring will be something in between code-golf and popularity contest:

Score = (upvotes - downvotes) - floor((bytes in code that outputs question) / 3)

The highest score wins.

(You can use http://mothereff.in/byte-counter as a byte counter.)

Answer 17

Infinitely spew corporate B.S.

^{(Throwing a touch of shade at some recent decisions made by StackExchange over on Mother Meta)}

If you've ever read a company's announcement blog post or press release, you've likely thought to yourself "Wow, I couldn't understand a word of that!" This is the effect of a marketing technique often referred to as "spewing corporate B.S." which, while often frustrating to read, can help you and your business dodge a lot of bullets in the P.R. department (or at least, buy yourself some time).

After recent actions made by the company you work at, you've realized that your company doesn't have time to formulate a good response to its customers' concerns—but you know just how to deal with the problem.

In this challenge, your task is to write a program or function that, given no input (or a seed), infinitely writes randomized company-speak.

How to write it

SANDBOXING: TODO - spec out how this will work. I'm thinking that it will just choose random words from a word bank, but I should specify how grammar can work, or maybe it would make sense for the word list to be taken as input (leaning towards this)f? Please comment any suggestions.

Here are some example corporate sentences your program may write, according to the above criteria:

We are revisiting a broader approach to improving the user-experience of our new experiment concerning recent concern.

We are excited to share a more holistic initiative to produce positive results from our new experiment.

We are committed to hearing your feedback in a more positive exploration of the product.

Rules

• Your submission can be a full- program or a function
• You may return a generator that can generate sentences infinitely rather than printing.
• Your “randomness” doesn’t have to be evenly distributed, but there must be a non-zero chance that any possible sentence might be outputted by your submission.
• SANDBOXING: more rules

Answer 18

Detect sloppy randomness

code-golfdecision-problem

The C rand() function is often implemented like so:

static unsigned long int next = 1;

int rand(void) // RAND_MAX assumed to be 32767
{
    next = next * 1103515245 + 12345;
    return (unsigned int)(next/65536) % 32768;
}

void srand(unsigned int seed)
{
    next = seed;
}

However this is not a very good rng and definitely not a cryptographically secure one. Your task is to write code that detects this rng.

Specifically your code takes as input a sequence of 100 (or fewer if you so wish) numbers between 0 and 32767 inclusive.

For a random input the code should output "random" with at least 99.9999% probability and "not random" with at most 0.0001% probability (one in a million).

However if the input is generated using (successive calls to) rand then your code must output "not random" always.

Also, your code must be fast. Specifically it should run in under a second. Output as per standard decision-problem rules.

Meta

Should I use a 64-bit rng? Solutions in fast languages can probably just brute force the 31-bit state. This would also allow to relax the time requirements.

Answer 19

Inspired, maybe copy background from there

Given a map, output a shortest possible input.

Test cases:

Start here _ /  => / \
             \

               /
              /
Start here _ /\/ => /// /\/ \/\
             \/\

                /
               /
              /\
Start here _ /\/\ => //// //\\ /\/ \/\/
             \/\/

                   /\/
                /\/\/
Start here _ /\/\/\/\/ => /\//\//\/ \/\//\// /\/\/\/\/ \\\
             \/\/\  /\    \/\/\\//\
              \   \/
               \

Answer 20

Python: *args or **kwargs?

Is it a regular argument or a keyword argument?

---

In Python, there are two types of specifying arguments to a function:

Regular argument (arg): f("regular argument")

Keyword argument (kwarg): f(keywordarg="keyword argument")

Keyword arguments in Python always are in the form of variable assignments and regular arguments are anything else. If you want to learn more about *args and **kwargs, click here.

---

Task

Given an input string consisting of only ascii characters that is a valid argument (regular or keyword), you must output one of two constant, distinct values representing whether it is an arg or a kwarg. Shortest code wins!

---

Test cases

3              -> arg
num = 3        -> kwarg
num=3          -> kwarg
a=b            -> kwarg
a==b           -> arg
False          -> arg
"kwarg"        -> arg
arg="arg"      -> kwarg
"kwarg=kwarg"  -> arg
a=b==c         -> kwarg
b==c           -> arg
[1,2,3,4]      -> arg
dict={1:2,3:4} -> kwarg
[1,2][i:=0]    -> arg

"""more than
one line!"""   -> arg

mstring='''
indeed more
than one line
'''            -> kwarg

---

Tags

code-golfdecision-problempython

---

Meta

• Is this a duplicate?
• Is this too focused on Python?
• Do I need more test cases?
• Any other feedback?

Answer 21

Decimal to fraction

In the pool of questions on CGCC, I have not found a question with this task.

---

Given a float in base 10, output a fraction in simplified form, improper or mixed. The output format can be any reasonable one. In code-golf, the shortest answer wins!

Test cases

3.5 -> 7/2 or 3 1/2
0.25 -> 1/4 or 0 1/4

---

Meta

• Did I miss a duplicate?
• Any more test cases?
• Anything else?

Answer 22

JSON Data? ASCII is better!

Write a function that prints JSON data using ASCII art, and takes a dictionary/object as input.

Example

Input:
{
    "columns": ["firstname", "lastname"],
    "data": [
        {"firstname": "John", "lastname": "Doe"},
        {"firstname": "Jack", "lastname": "Barrock"},
        {"firstname": "John", "lastname": "Skeet"},
        ....
    ]
}

Output:

+---------------------------+
|  firstname  |  lastname   |
+---------------------------+
|     John    |     Doe     |
|     Jack    |   Barrock   |
| ...                       |
+---------------------------+

This is code-golf, so fewest bytes win.

Note: The input will always have a column attribute, and will always have a data attribute. Think of it as SQL.

Answer 23

Worst algorithm for anything

Now, any coder worth their salt will know how to sort an array in-place in nlogntime. Most can probably figure out a way to do it in n!n time and factorial memory usage. Let's see an algorithm that tops those numbers; can you come up with a way to sort an array in up-arrow time? Can you come up with an algorithm whose O-notation contains the Graham's number series?

Rules:

• The algorithm must solve a problem that isn't just an obfuscation of 'do a ridiculous amount of NOPs".
• Highest O-notation in either memory usage or time wins, tie broken by the other one and then by a golfed implementation.

Discussion

I'm not sure whether I should limit this to solving a specific problem. For that matter, I don't know if this would be an interesting challenge.

Answer 24

Catouterr

A cat that writes to two streams? I’m in!

---

Write a full program with these properties:

• If the input string ends in outerr, remove that part and write the rest to STDOUT and STDERR.
• If the input string ends in err but not outerr, remove that part and write the rest to STDERR only.
• If the input string ends in out, remove that part and print the rest to STDOUT.
• Otherwise, print it to STDOUT unchanged.

STDOUT and STDERR can be replaced by a reasonable alternative. Also, STDERR is not ignored. However, insuppressible messages are ignored.

This is code-golf, so shortest code wins!

---

Meta

• Ask away!

Answer 25

Underhand Bejewled

Help me to write a game of bejewled, which cannot be lost!

Bejewled game rules

If you ever played bejewled, you can skip this, but for those who did not see it ever:

• Playing field of 8*8 grid is filled in with gems of 7 different types randomly
• By swapping two adjective stones, your goal is to create a line of at least three same type of stones in the either vertical or horizontal line
• If did so, the gems will dissappear, points are added (say 20 points for a matching) and new gems are provided randomly from the top
• image related:

Your challenge

Provide me a game which cannot be lost. In other words, the gems falling from the top are not random at all, but are falling in order that there is always at least one possibility to match three gems

But, from looking at the code at level of newbie programmer, it should look like that game acts as if it was random

Output

Playable game. As long as it is the grid of 8*8 filled in with 7 different types of "gems" the game is ok. It does not to have killer graphics, neither it does not need to be playable by mouse. (But in that case please make sure you show which "gem" is hovered and then selected)

Winning criteria

This is popularity contest. So highest rated game wins

Answer 26

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.

Answer 27

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.

popularity-contest

Answer 28

Winning Tic-Tac-Toe lines

fastest-code

For a given tic-tac-toe board of size N**D (for example, a normal tic-tac-toe game is 3**2), the number of winning lines of length N is given by the expression:

$$ 2^{D-1} + \sum_{S=1}^{D-1}2^{S-1}DN^{D-S} $$

(Basically, you are summing the number of lines in each S-dimensional slice of the board.)

The challenge:

Given N and D, your answer should output a list of D-dimensional coordinates for each winning line. Input and output are any reasonable format. You can assume that both N and D are positive integers, with N > 1. (Degenerate cases of N=1, D>1 not included.)

Since this is fastest-code, fastest answer wins. Please explain your algorithm!

Answer 29

Ayn Random number generator

---

Inspired by xkcd 1277:

Write a random number generator that takes no input and generates a random integer between 1 and 100. When run less than 200 times, the frequency of all numbers needs to be between 0 and 2, but when it's ran 50 000 times, the number 42 (obviously) should have a frequence that's more than 4 standard deviations higher than the mean.

Format is code-golf. Your score is the bytecount of your code.

Answer 30

Please nitpick this. If there's anything that wouldn't work or would be inconvenient, however small of an issue it is, tell me about it!
Also, suggestions for [adjective] are more than welcome.

---

Determine how [adjective] a number is (code-golf)

A number would be considered [adjective] if 0 is the result of multiplying its digits together, then multiplying the digits of the resulting number, then repeating until a single-digit number is produced. The more steps it takes to reach 0, the more [adjective] the number is; if the resulting number is not 0, though, the number is not [adjective] regardless of how long it took to finish.
The formula used to determine [adjective]-ness is 10-10/T where T is however many numbers it took to reach 0 (including 0 and the initial input)

Your goal is, as the title says, to write a program or function that determines how [adjective] a number is, and prints every iteration along the way. Here are some example inputs/ouputs:

in: 879
out: 879    <-       (T=1)
     504    <- 8*7*9 (T=2)
     0      <- 5*0*4 (T=3)
            <- optional newline
     6.6... <- 10-10/3 (repeating decimals can be expressed in any way you want)

in: 2468
out: 2468   <-  T=1
     96     <- (T=2) 2*4*6*8
     54     <- (T=3) 9*6
     20     <- (T=4) 5*4
     0      <- (T=5) 2*0

     8      <- 10-10/5

in: -888
out: -888  
     -512   <- -8*-8*-8
     -10    <- -5*-1*-2
     0      <- -1*0

     6.6... <- 10-10/3

in: 1344
out: 1344
     48
     32
     6

     0    <- did not produce 0, so the prog/func returns 0

Your program must follow these rules:

-Takes input from STDIN.
-Throws an "error" (printed to STDOUT) and halts immediately after input if the input has one or more 0s in it or if it's less than three digits in length. The error must be a string, and as it's supposed to be printed to stdout, cannot be one generated by the language itself (eg 1/int(min(input())) to check if it's zero). Lastly, the error message has to clearly define what the error is; ERR:0 and ERR:LEN, for example, would suffice.

Bonuses/Penalties:

-25 if it properly handles decimals. For instance, an input of 99.22 would first turn into 9*9 + 0.(2*2), or 9*9 + 0.4, and so on.

---

This is code-golf, so the shortest answer in bytes wins.