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

Write a program who return the current month.

The Rules

• The result needs to be correct even if the program is run in the future.
• It's code-golf so the shortest code wins!

---

Optional

Add an interpreter so the submission can be tested. It is allowed to write this interpreter yourself for a previously unimplemented language.

---

^{It's my first code-golf idea I'm fully open to improving it with more experienced users.}

code-golf date

Answer 2

Output Infinity (updated v2)

code-golf kolmogorov-complexity

Challenge

Output the following infinity symbol:

         ∞∞infinity                         ∞infinity                   
     infinity∞∞infinity                 infinity∞∞infinity              
   infinity∞∞∞∞∞∞∞infinity           infinity∞∞∞∞∞∞∞infinity            
  infinity        ∞∞infinity      ∞∞∞∞∞infinity        ∞∞∞∞∞∞∞          
 ∞∞∞∞∞                 ∞∞∞∞∞∞∞  ∞∞∞infinity               ∞∞∞∞∞         
 ∞∞∞                      ∞∞∞∞∞∞∞infinity                   ∞∞∞         
∞∞∞                         ∞∞infinity                       ∞∞∞        
∞∞∞                       ∞∞infinity                         ∞∞∞        
 ∞∞∞                    ∞∞∞∞∞∞infinity                      ∞∞∞         
 ∞∞∞∞∞               ∞∞∞infinity  ∞∞∞∞∞∞∞                 ∞∞∞∞∞         
  infinity       ∞∞∞∞∞infinity     ∞∞∞infinity        infinity          
    infinity∞∞∞∞∞∞∞infinity           infinity∞∞∞∞∞∞∞infinity           
      infinity∞∞infinity                infinity∞∞∞infinity             
           ∞infinity                        ∞∞∞infinity                 

Rules

• No input.
• Output can be given in any convenient format.
• Any number of trailing spaces at the end of each line is allowed.
• Any number of trailing new lines at the end of the shape is permitted.
• Either a full program or a function are acceptable. If a function, you can return the output rather than printing it.
• If possible, please include a link to an on-line testing environment so other people can try out your code!
• Standard loopholes are forbidden.
• This is code-golf so all usual golfing rules apply, and the shortest code (in bytes) wins.

Answer 3

Reverse Code Golf- Print out two by using variables a and b that both equal one and adding them without any extraneous lines.

Your task is very simple, display that 1+1=2, except you need as many commands and non extraneous lines as possible.

What counts as non-extraneous? If one cannot remove any kind of sequence or segment of commands, then the program is counted as non-extraneous. The variable names need to be only one byte each, without any kind of trailing zeroes or insignificant digits.

Input: nothing

Output: "2" or 2 or whatever, as long as the program runs 1+1.

Sample: Java- System.out.println( Integer.parseInt( "1" ) + Integer.parseInt( "1"));

Answer 4

Send the pairs

Write two program A and B. A takes 1024 pairs of integers (a,b), where 0≤a<2³², 0≤b<1024, and all as are different. Output a positive integer. B take the output of A and one a from the input pairs of A, and output its b.

Smallest output of A under a same random test data win.

Answer 5

Write a program that takes a list of strings as input and creates trees of prefixes as such:

Hi_there_how_are_you?
Hi_there_would_you_mind?
Hi_the_weather_is_nice
Hills_are_green
Many_of_us
May_has_11_days
May_has_11_days_left
IWillLearnTheTrombone
IWillLearnTheSaxophone
IWillLearnThePiano

Which would output:

Hi Hi_there Hi_there_how_are_you?
            Hi_there_would_you_mind?
   Hi_the_weather_is_nice
   Hills_are_green
Ma Many_of_us
   May_has_11_days May_has_11_days
                   May_has_11_days_left
IWillLearnThe IWillLearnTheTrombone
              IWillLearnTheSaxophone
              IWillLearnThePiano

The input strings shall contain no spaces and the output shall be separated by at least one space, any number of extra line breaks or spaces are allowed. The output above is formatted to explain the challenge, the following formatting is also valid:

Hi Hi_there Hi_there_how_are_you? Hi_there_would_you_mind? Hi_the_weather_is_nice Hills_are_green Ma Many_of_us May_has_11_days May_has_11_days May_has_11_days_left IWillLearnThe IWillLearnTheTrombone IWillLearnTheSaxophone IWillLearnThePiano

This question is a kind of reverse of this Prefix Tree Traversal. This is code golf, shortest code in bytes win.

Note: I'm struggling with the output? What would be the most 'fun'/ have high potential for cleverness? The one I have now just looks like a mess. Can i have output as a list of lists(of lists)? Or do that hinder people?

Answer 6

code-golf

I'm glad the sandbox exists because I have a few issues coming up with the right wording for this.

Background

Theoretically, any numeric pattern should exist somewhere in the decimal places of pi.

Challenge

Given any numeric input, find the index (location?) of the first occurrence of that input in the decimal place of pi

Example cases:

• 1 = 1
• 14 = 1
• 41 = 2
• 897 = 11

Rules:

any numeric input, can't see why it should be limited by any number of characters. I am not sure about limitations, but this could get computationally intense if it's a large sequence of numbers that occur very deep into pi. Do I need to add any restrictions to cater for computational complexity?

Answer 7

Tags:

Code-Bowling

Name: Two is an error, One runs fine!

The challenge is simple.

When one character is removed from the given program, it should not error, but when two are removed, it should error.

PENALTIES:

If you repeat one Unicode character in the program, then your score will be the number of bytes subtracted by the Unicode value of the character (0 for NUL, 10 for newline, 64 for A, etcetera).

Else, your score is the number of bytes.

As always, since this is code bowling, most bytes win!

Answer 8

Output a number \$n\$ such that:

1. \$n\text{mod}10=5\$
2. \$n^2\text{mod}10^{10000}=n\$

Shortest code win. You should be able to try it rather than purely know it work.

Sandbox mainly to check duplication

Answer 9

Integer or decimal to array and array to decimal or integer

Task

Write two functions

1) Convert an integer or decimal to array of integers that potentially includes a single decimal

2) Convert array including integers and potentially a single decimal to integer or decimal

Input

Integer or decimal to array

• An integer or decimal

Array to integer or decimal

• An array

Output

Integer or decimal to array

• An array containing each digit of the input at an individual index with the first decimal portion of input containing the decimal character.

Array to integer or decimal

• An integer or decimal equal to input

Specification

When the first digit of a decimal is a 0 , and a digit follows, that value includes all 0's up to and including the last digit of that decimal, else the decimal portion is spread or expanded to the remainder of the decimal portion for the remainder of indexes of the array, that is: -0.01 <-> [-0.01], 100.01 <-> [1,0,0,0.01], 100.0001 <-> [1,0,0,0.0001]

Test cases

Input <----------> Output

-123               [-1,-2,-3]
4.4                [4,0.4]
44.44              [4,4,0.4,4]
-0.01              [-0.01]
123                [1,2,3]
200                [2,0,0]
2.718281828459     [2,0.7,1,8,2,8,1,8,2,8,4,5,8,9]
321.7000000001     [3,2,1,0.7,0,0,0,0,0,0,0,0,1]
809.56             [8,0,9,0.5,6]
1.61803398874989   [1,0.6,1,8,0,3,3,9,8,8,7,4,9,8,9]
1.999              [1,0.9,9,9]
100.01             [1,0,0,0.01]
545454.45          [5,4,5,4,5,4,0.4,5]
-7                 [-7]
-83.782            [-8,-3,-0.7,-8,-2]
1.5                [1,0.5]
100.0001           [1,0,0,0.0001]

Winning criteria

Least amount of total (each of function or programs 1 and 2) bytes used.

code-golf

Answer 10

Introduction

The original creator of this meme has gone blind, lost his internet and accidentally deleted all his memes. Except this one. He has this one last meme on his desktop, and since he can't see, he wants to know what this meme is.

By hearing it.

Challenge

Your challenge is to write the shortest program that will produce a playable audio file that the meme creator will play to hear the text in this meme.

• The input is the meme below
• The output will be a audio file that reads the output text in English and has a slight pause after a colon or a new line. But don't read out 'colon'

Answer the following questions for your readers.

• You can use any programming language
• You can use any existing library
• Output audio must be playable by vlc
• Networking is not allowed, you cannot connect to any internet services
• Shortest answer wins

Input and Output

Input:

Output:

Me: spends 8 hours per day on the internet

Eyesight: gets worse

me:

Answer 11

Compress briefly

Compress and decompress the first chapter of Worm, beginning with the opening words "Class ended" and ending with the closing words "my best friend." (including the period). You do not need to include any of the formatting (copy and paste as plain text).

Rules

• You may not use any built-in or imported compression functions or procedures. You must implement the compression yourself.

• You may either write one program to compress and another to decompress, or one program that does both. If you wish, the second option can be a polyglot, where compiling as one language compresses and compiling as the other decompresses.

• Your program must be no more than 2000 bytes long. You may, at your option, compress your program with bzip2 or gzip before measuring its size for the purpose of meeting this limit.

• Your program does not need to work for any other text.

• Standard loopholes apply.

• Standard I/O rules apply.

Scoring

• The score is the sum of the total number of bytes of your program(s) and the total number of bytes in the compressed text.

• If you use a single program to compress and decompress, then you may have to pay a penalty. Specifically, you must pay a number of bytes equal to the Levenshtein distance between the shell command needed to (compile and) run your compression program and the one needed to run your decompression program. You can calculate this online. A special exception: if you choose to write a polyglot, then you can leave out the paths to the compilers/interpreters when you calculate the penalty.

Tags: code-challenge, compression

Answer 12

Output an alphabet suite

restricted-source kolmogorov-complexity code-golf code-challenge

A successor to the ŋarâþ crîþ alphabet challenge.

Outputting the alphabet song with as few letters as possible was too easy, but what about outputting many of them?

Your challenge is to write as many programs as you can, with no two programs sharing any Unicode codepoints, and each program outputting the names of the letters of the alphabet (or the glyphs of some other kind of phonetic script) used by a different language. For instance, one program can output

a bee cee dee e eff gee aitch i jay kay el em en o pee cue ar ess tee u vee double-u ex wye zed

and another program can output

a be ce de e efe ge hache i jota ka ele eme ene eñe o pe cu erre ese te u uve uve doble equis ye zeta

Notes:

• For a given language, there will probably be some leeway in what you can output.
• Unlike in the previous challenge, you don't need to worry about any particular punctuation. You should at least separate each letter name with whitespace.
• You must output the names of the letters, not the letters themselves (so A B C... is invalid), unless the letters are literally pronounced so in the language in question.
• If a language uses both capital and lowercase letters, then you may output the letter names in either case. If it uses only one of them, then you must output the alphabet in that case.
• You must use a different language's alphabet for each program, but you are allowed to use the same script in the context of different languages.
• Constructed languages are allowed, as long as they predate the challenge.
• You may use different programming languages for each program. Or the same.
• Standard loopholes are forbidden.

TODO:

• is the requirement against sharing any codepoints too strict?

Answer 13

add two numbers in string representation

Idea:

Given two strings representing non-negative integers in base 10, return the string corresponding to their sum - without any explicit arithmetic operations. This means you have to implement incrementing (probably with a lookup and indexing) and carrying (probably with iteration or recursion) on your own. Comparisons and boolean operations are allowed.

Examples:

"1" + "1" = "2"
"5" + "6" = "11"
"0" + "8" = "8"

I/O:

Write a function or program which takes the two strings in a way you want to.
Output, print or return the solution in whatever way you want.

Ah, and also don't forget that this is code-golf, so shortest answer in bytes will win. Also, all standard loophole rules and so on apply (you should know from all the other challenges!)

---

Sandbox

This challenge changed, evolved and got compressed during discussion with Adám starting from here (feel free to review the edits and chat of this post on how we got here)

Tags for cgcc post:

math addition code-golf restricted-source

Answer 14

The goal is to make a program that is compilable in as many languages as possible.

• The program must be compilable with a specific compiler version and compiler parameters without any errors.
• The program may result in an error when run.
• The source code must not be empty or whitespace.

Answer 15

Writing a WebCrawler

Challenge

Design a web crawler that recursively extracts all the hyperlinks from the HTML of the web page and does the same for every hyperlinked page it finds. The webcrawler must store the hyperlinks in a separate file

How The WebCrawler Works

First the webcrawler should download the HTML file of the URL the user inputted.

Second the webcrawler will copy every single hyperlink embedded in the hyperlink and paste it into an output text file. The best general way to do this based on my experience is to have the webcrawler iteratively search through the HTML file for an "a href" tag. Be careful about what kind of hyperlinks are embedded in those tags. Sometimes only the subdomain directories of a complete hyperlink are embedded in this

For example: https://en.wikipedia.org/wiki/Toyota may simply have an a href tag in the HTML file of a webpage as: "/wiki/Toyota"

After extracting all the hyperlinks of the first webpage, visit all the hyperlinks found on the base webpage starting from the the first hyperlink found and repeat all the steps above. The only exception to doing this is obviously if the hyperlink fails to lead to an HTML page.

Input

The program must accept only one URL as input.

Output

A text file that lists every hyperlink that it finds. Note:

Your webcrawler must avoid revisiting webpages it has already crawled. This can cause the crawler get trapped in a "circular link loop" where it continously visits the same pages endlessly.

Note:

Special consideration will be given to submissions that prove they are capable of crawling deep web websites, including those with the .onion sites.

Answer 16

Create a "Transpiler"

for the purpose of this challenge, a transpiler is any program that takes valid source code from one language as input and produces a program valid in another language that performs the same actions. Calling the original languages interpreter is not banned.

Posts should start with "SRCLANG to DSTLANG in LANG; X bytes" as a heading.

Here's an example post:

Shell to Ruby in Ruby; 41 bytes

puts'`bash #{Data}`
__END__
'+STDIN.read

Here we use the somewhat obscure Data constant to embed arbitrary data in the program. this has the advantage of never having to escape anything.

Each "triple" of source, destination, and working language represents its own category, as this challenge varies greatly in difficulty depending on the languages used.

Answer 17

I have the following code. Help me make it code shorter.

new Promise(r=>r(URL.createObjectURL(new Blob(['<h1>Example</h1>'],{type:'text/html'})))).then(u=>open(u)&&setTimeout(t=>URL.revokeObjectURL(u),2e3))

The Catch:

• This has to be in JavaScript
• It cannot contain semicolons
• It must be a "one-liner"
• It must have the same steps as the code above:
  1. Create a blob URL from a blob
  2. Open a browser window of the blob URL
  3. Revoke the blob URL

Extras

• The winner will be decided by the shortest amount of bytes
• If you try this in another language, you will still get an upvote

Answer 18

pi optimized-output

Most digits of Pi in a hundred bytes

Answer 19

Reinvent math

The task is simple. Define the basic operators (+, -, *, /) without using them directly.

Also banned:

• any add-assign (+=) and its equivalents
• basically anything intended to be used as a basic arithmetic operation

Program should consist of at least 4 binary functions, one for each operation. they may call other functions defined in your program, including each other. The types of the arguments to the function may be any types that the basic arithmetic operators work on, except for types that are less than 3 bits in size.

Shortest code wins

Answer 20

Enumerate all possible IPv4 addresses

Title might make the challenge hard, but it's easy.

You have to print all the possible IPv4 addresses from 0.0.0.0 to 255.255.255.255

Standard loopholes apply, no internet usage for this

Tags: code-golf,kolmogorov-complexity,string

Answer 21

Google search

Challenge is very simple, you have to get a string as input and then launch the default web browser, and search for that string in Google.

Input string will have only characters a-zA-Z

Google search URL is google.com/search?q=querystring

Standard loopholes apply, Internet connection allowed, but only to google.com domain

Tags: code-golf,internet

---

Author note: challenge title sucks, please improve it!

Answer 22

Reverse error quine

code-golf,quine

Based on this

Write a quine that prints it own source code in reverse, but to STDERR.

Penalties

• +200 using other files I.E. reverse.txt
• +150 internet usage
• +100 reading own source code

Rules

• Minimum length of source is 2 bytes

• Standard loopholes apply

code-golf, shortest code wins

Answer 23

“Simple” Programming Homework

code-golf restricted-source

---

Your friend has been caught sleeping in class again! As punishment, his computer science teacher has assigned him homework, knowing that he will not be able to solve it due to not having paid any attention.

The assignment seems deceiving simple at first; all that is required is to output the string:

John Doe

Unfortunately, the teacher is intent on making the simple assignment much more difficult. Since your friend was not listening when the teacher explained the concept of strings and numbers, the teacher forbids him from using any number character (0-9) or the quotes (", ', `).

Can you help your friend solve this problem with the shortest code possible, and save his computer science grade in the process?

Try to find the shortest code in each language!

_{Note: it is encouraged to try to solve this problem in languages where string/character literals exist but cannot be used due to the restrictions (most mainstream languages are like this, e.g. C++).}

Answer 24

Geometry Dash Clone in a weird Way?

code-challenge cloning-games

Try to make a functional clone of Geometry Dash in the shortest time.

How GD Works.

• You have a cube. In the clone, it can be as small as you want, but no bigger than 2x2.
• You have to jump over spikes. The key to do this is (preferably) the up arrow key, but can be any option you want (simply tell me in your answer what key is it.
• If you touch the spikes, the screen says "Game Over." and exits in 3 seconds.
• There are blocks! You can jump on them, but touching them from the left side results in the same thing that happens if you touch the spikes.
• A song plays in the background. How you do this is up to you.

Rules:

1. 3 Extra points for working forwards and backwards.
2. Must have the letter a 5-7 times and no q at all!
3. Allows ascii art type output and text input (standard input)!

Sandbox Questions

How is this even going to work?

Answer 25

Get Floor of N ^ (3 / 2)

Your task is very simple:

Get The Floor of N ^ (3 / 2)

OEIS

This is Code Golf so the winner wins

Test Cases

0 => 0
1 => 1
2 => 2
3 => 5
4 => 8
5 => 11
10 => 31
13 => 46
27 => 140
33 => 189
49 => 343
68 => 560
89 => 839
98 => 970
100 => 1000
136 => 1586
256 => 4096
500 => 11180
147385 => 56582212

Meta

• Any feedback?

Answer 26

Who Loses The number guessing game?

You are playing a number guessing game. You know everyone's guesses, and who won, and want to figure out who was in last place.

Task

Your task is to take a dictionary of guesses as input, along with the name of the winner. You should then return the name of the player whose guess was the farthest from the winner's, or if there are multiple, the lowest.

A input:

[{"Joe": 800, "Mama": 1000, "Biden": 1200}, "Joe"]

Means that the aproxximate score winner is Joe, The next is Mama, Mama is greater than Joe and Mama is greater than Biden.

So the loser is Biden.

All guesses are guaranteed to be unique

Test cases

[{"A": 100, "B": 200, "C": 300}, "A"] => "C"
[{"Hello": 200, "World": 201}, "World"] => "Hello"
[{"Blah": 210, "Bruh": 984, "Boo": 314}, "Boo"] => "Bruh"
[{"A": 6, "B": 7, "C": 666, "D": 1000}, "C"] => "A"
[{"AC": 100, "BE": 200, "CE": 300}, "B"] => "CE"

Meta

• Any feedback?

• Dupe?

Answer 27

Convert decimal to unary in fewest regex codes code-challengeregular-expression

Your task is to Convert decimal to undary in fewest regex codes

Every regex code is substitution mode.

The regex code counts the regex code, without test string and Substitution code

A example

^2, |11
^3, |111
^4, |1111
...
\|, <empty>

This scores infinity, But don't try this.

Rules

• Your score is always non-infinity

• Any flavor is allowed.

• Your score is the number of regex codes

• every length of regex code is non-infinite

Meta

• Any feedback?

Answer 28

Nth Eights Challenge

Inputs:

There are 2 inputs: The amount of eights to be used in the calculation, and the number to solve for.

What to solve:

The program needs to insert operators in between each eight, so when the newly created equation is calculated, the answer is the number that was trying to be solved for. When the equation is calculated, there is no operator priority.

Rules:

The only operators allowed are:

+
-
*
/
(And parentheses)

You may insert multiple operators between each number. No extra numbers are allowed. There must be an operator inserted in between each 8. The answer must be displayed when the program finishes.

Examples:

#User inputs
Amount of eights: 4
Solve for: 15

#Answer
8+8-8/8

#User inputs
Amount of eights: 4
Solve for: 10

#Answer
(8+8)/8+8

Winning Criteria:

The winning criteria is for the program written in the least amount of characters.

Answer 29

Get the Nth line

Challenge

Let's have a file f and a number n. Your task is to get the nth line from the file.

Constrains

• file f exists and has at least n lines
• you can index lines from 0 or 1, whichever you prefer

Example

• input: n = 2 (indexing from 1) and content of file f is:

foo
bar
baz

• output: bar

Rules

• this is code-golf challenge, so the shortest code wins
• standard rules apply for your answer with default I/O rules, so you are allowed to use stdin/stdout, functions/method with the proper parameters and return-type, full programs
• default Loopholes are forbidden.

Answer 30

Knight mover

Your task is to move a chess knight between the points B and E.

A chess knight moves in an L shaped pattern, like so:

.X.X.
X...X
..B..
X...X
.X.X.

The Xs mark where the knight in position B can move.

There may be other chess pieces on the board, blocking the knight's movement, but for clarity, you will only be notified of where you cannot go by # characters. You cannot land on these marked spaces, but you can go over them. You also cannot go outside of the board.

Your goal is to find how many turns N are needed to go from B to E, or return -1 if it can't be done.

Input & Output

• You are given 2 integers W and H giving the width and height of the board
• For the next H lines, you are given a row of the board, containing the characters B, E, . and #
• You are allowed to take in the input as a WxH board as a list of strings or a character matrix

Test case

3 2
..E
B..
->
1


5 5
B...E
..#..
.....
.....
.....
->
4


7 5
B..###.
####.##
...###E
..#.#.#
.#..#..
->
4


8 8
....#...
....##..
..E..#..
#...##..
.###....
........
........
.....B..
->
6

This is code-golf, so shortest code wins!

Credits to this puzzle