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

This was heavily inspired by the donut.c program

---

Challenge:

You have to come up with a program that prints (in console) a shape that looks exactly like the shape of your code.

For example, if your code's shape looks like this:

    2343
3kf5
     3o*/f
   3%kt^7

then the output's shape should look like this:

    9I8b
&yt^
     )ph67
   {}fgh]

(the byte don't need to match, just the shape)

Rules

• Empty programs/whitespace-only programs are not allowed.

• Your program should have more than 2 lines/statements of code.

• Each line should not be identical to every other line.

• All whitespace characters (space, tab,...) don't have to be identical.

• Whitespaces characters don't count towards the minimum bytes count.

• Your program's source code and the output should not be identical. It should be at least has one different character.

• The output should have at least two different bytes on one line.

• You should not use comments.

Scoring criteria

• Longest code (in bytes) wins!

• If two same programs have the same byte count, the one with the most unique characters in the output wins!

• If two same programs have the same unique characters, the one with the most different characters in output compared to source code wins!

---

Meta

• Does this question have any duplicates?

• My wording is bad, can you improve it?

• Is this question interesting? Fit within the rules of the site?

Answer 2

Get all binary between a binary number and its reverse

Answer 3

Challenge

You should write a program that has one in (your code in bytes) chance to output a 4 (could be a function that returns a 4). So if your code has 10 bytes, your code should have 1 in an 10 chance to print out a 4. Otherwise, output "finding my dice".

Rules

• You can use whitespaces, comments or any unnecessary code to get to the number of bytes that you want.
• You shouldn't use any loopholes.

Winning criteria

This is code-golf, so shortest code in bytes wín!

Answer 4

Find duplicates, quickly

In this challenge, you'll be given a list of positive integers or non-empty alphabetical strings (your choice), and must return a list containing all duplicates. You must do this with the minimum time complexity you can, and as few bytes as possible.

Task:

Given a list of either positive integers or non-empty alphabetical (lower or uppercase, your choice) strings, return a list containing all duplicates. You may contain a duplicate value any number of times, so for the input [a, b, b, c, d, d, d, d], any of [b, d], [b, d, d, d], [b, b, d, d, d, d], or even [b, b, b, b, d] would be fine.

Scoring:

Scoring is by both average time complexity and bytes. A better time complexity will always beat an answer with a lower one, and byte count is a tie breaker. E.g., if there are two \$O(n^2)\$ answers, at 10 and 20 bytes, and an \$O(n\log{n})\$ answer at 140 bytes, it would rank higher than either of the others (until either a shorter \$n\log{n}\$ answer or an answer faster than \$n\log{n}\$ showed up).

As in code-golf, this is per-language, so Vyxal and Vim, Charcoal and C, or Japt and Java are not competing.

Answer 5

Check if the string is reshaped.

Answer 6

Dumbo octopus flashing time code-challenge

Day 11 of this year's AoC was about a grid of bioluminescent dumbo octopi. I'll try to explain how this works, click on the link for a better explanation.

You have a 10x10 grid of octopi which slowly gain energy and flash when fully charged. Each octopus has an energy level from 0 to 9:

5483143223
2745854711
5264556173
6141336146
6357385478
4167524645
2176841721
6882881134
4846848554
5283751526

The flashes and energy amounts can be modelled with steps. At each step:

• All octopi have their energy level increase by 1
• Then, any octopus with an energy level greater than 9 flash. When an octopus flashes, it increments the energy levels of all octopi adjacent (orthogonally or diagonally) to it.
• The flashing repeats until no more octopi can flash. Then, all octopi that flashed during this step have their energy level reset to 0.

For example (stolen from AoC):

Before any steps:
11111
19991
19191
19991
11111

After step 1:
34543
40004
50005
40004
34543

After step 2:
45654
51115
61116
51115
45654

In step 1, the octopi with energy level 9 are all incremented to 10 and flash, all incrementing the octopus with energy level 1 (initially incremented to 2) in the center and causing it to flash as well.

The second part of the puzzle asks how long a configuration will take to have all octopi simultaneously flash in the same step. However, not all configurations will do this - some will fall into other cycles. Eventually, all of the configurations will repeat themselves, as there's only \$10^{10 \cdot 10 } = 10^{100}\$ possible configurations - still a huge amount, but finite.

Your challenge is to find a configuration that takes as many steps as possible to return to a configuration it's reached before, with more steps being better.

People on reddit have been investigating this, and the number to beat is 372886.

Meta

Is the explanation good, and should I bother with it?

Better examples?

Answer 7

Kolmogorov-simple numbers

Answer 8

Return all letter counts as an integer

Answer 9

Repeat average

Answer 10

Event scheduler

Answer 11

Identify basic building blocks for new natural and programming language

(Based on Invent new programming language and write Hello world in it, but re-phrased to gain more focus on answers).

There exists variety of different programming languages, also variety of natural languages.

If we could create new programming language, which in a turn would possess structure of natural language - what basic structures you would choose ?

one example of artificially constructed language is Toki Pona:

• https://simple.wikipedia.org/wiki/Toki_Pona
• https://omniglot.com/language/phrases/tokipona.htm

It can be used as natural language, but not as a programming language.

One example of programming language is for loop - for example in C#:

for(int i = 0; i < 10; i++) { ... }

If you want to express this kind of sentence in natural language - then you can use 'equals' for '=', 'less than' for '<' - but scope begins ('{') and scope ends ('}') is relatively long and difficult to express / pronounce.

What basic language structures you would propose for new language ?

Answer 12

Identify a "reverse checkers" position

Answer 13

High throughput prime numbers

Answer 14

Find out what type of adjective it is

There are 3 types of adjectives: absolute, comparative, and superlative adjectives. Your program should print what type of adjective it is. The program is supposed to work on finite lost of words.

Notes

• Input will be a string, (not always 1 word), it'll be an adjective (the number of words will be finite)
• Output must be anything that represents absolute, comparative and superlative.
• The 15 adjectives below should be used as test cases and your program should be at least 90% accurate.

This is code-golf, so the shortest code wins!

Test cases:

pushiest => superlative
homeliest => superlative
most miserly => superlative
outgoing => absolute
most feline => superlative
roasted => absolute
frightening => absolute
fairer => comparative
more uncomfortable => comparative
more classic => comparative
smarter => comparative
muffled => absolute
scratchier => comparative
meager => absolute
tartest => superlative

Answer 15

Is it a mathy-county-number

So I recently reinvented some boring type of number. Reinvented because I'm sure somebody else invented it before, but 'till figure out who invented it, let's call these numbers mathy-county-numbers.

So what is a mathy-county-number?

A mathy-county-number number is a number whose count of each digit also appears in the number.
It's a number like 332222410.
The number 3 occurs 2 times, so there must be a 2. The number 2 occurs 4 times, so there must be a 4. 4 occurs once, and some other numbers occur 0 times.

The task is simple: Write a program to check if a number (received by the input) is a mathy-county-number.

Rules

• Default loopholes apply
• Default I/O rules apply
• Output must be a truthy or falsy value
• No digit will appear more than 9 times

Examples

332222410
> True

33222241
> False

1
> False

33222
> False

1122233334444455555566666667777777788888888890
> True

112223333444445555556666666777777778888888889
> True

122334444456789
> False

Answer 16

Wordle

The game Wordle is quickly becoming popular.

The way the game works is as follows:

1. Players are trying to guess a 5 letter word
2. Players have six attempts to guess the word
3. After each attempt, the player is told:
   a. which letters are in the right place (index)
   b. which letters are in the word, but in the wrong place
   c. which letters are not in the word at all

The aim of this challenge is to create a Wordle application, as follows:

1. On startup, the application reads from a dictionary of 5-letter words and selects one at random
2. The application then prompts for user input
3. On input:
   a. The application checks the input to ensure it is also a 5-letter word and in the dictionary. If it is not, the application returns any failure message and exits
   b. If the input matches the chosen word, the application returns any success message and exits
   c. Otherwise, the application checks the letters of the input against the letters of the word, and returns to the user an indicator for each letter of whether it is correct, misplaced, or incorrect. If a letter is repeated in the input, only the first occurrence is marked as correct/misplaced; the remaining occurrences are marked as incorrect [sandbox qn: what happens if the actual word has repeated letters?]
4. Steps 2 and 3 are repeated until the application aborts in step 3a or 3b; or the user has failed to guess the word a total of 6 times; at which point the application exits

Sandbox

I am thinking of this as a code-golf challenge, but I wonder if there's another approach where people create the bot that's trying to solve the challenge, as well as the bot that's providing the challenge? Or something else? I'm not familiar with the other types of challenges to suggest something.

Answer 17

Universal Command Sequence

Posted

Answer 18

Generate Fmbalbuena Numbers

Answer 19

Generate Matching Regexes

Write a program that takes two lists of strings and generates a javascript regex that fully matches all the strings in the first list and matches none of the strings in the second list.

To be specific when for all stings in the first list str.match(\[your-output]\) must produce a match for the full string and for all strings in the second list str.match(\[your-output]\) must produce no matches.

Scoring

Your score is the average length of the regexes you produce not the length of your program. Your regexes should be tested against this file: https://pastebin.com/9iNZvGJC. Take the file in blocks of 20 lines and run your program with the first ten lines to match and the second ten to not match. Average the lengths of your program's output for all of the blocks in the file. This is your score.

Rules

• Do not output the \ for the regex

Answer 20

Help Bob split his apples

Bob has a lot of apples, and he wants to split his apples with his friends evenly. (Including Bob.) However, every \$k\$th friend already has a lot of apples and does not need apples. Bob, however, is kind so he gives each \$k\$th friend the number of apples the friend already gives floor divided by three.

Given the input format below, a number \$k\$, and a number \$a\$ for the number of apples, output the number of apples that each person receives.

Test Cases

[0, 0, 80, 0, 0, 45, 0, 0, 12] 3 100 => [10, 9, 26, 9, 9, 15, 9, 9, 4]

Answer 21

Move the next greater number, with fewest fails to take everything

Your task is to move the next greater number, with fewest fails to take everything

A fail counts if a step is the lower number (not counting equal)

The starting point is the top left corner

Example:

1234

Can do like this

>>>

Because moves to right, the next number is greater than previous

But

124
435

Is impossible so the fewest fails are:

>>v<<

1 > 2 > 4 > 5 < 3 > 4

So this has 1 fail

Test cases:

The output is not exact, there are multiple possible solutions

Input:

123
245
175

Output:

>>vv<<^>

Input:

123456789

Output:

>>>>>>>>

Input:

987654321

Output:

>>>>>>>>

Input:

123
456
789

Output:

>>vv<<^>

Input:

123456789
987654321
123456789

Output:

>>>>>>>>v<<<<<<<<v>>>>>>>>

Meta:

• Any feedback?

Answer 22

Euler Irregular Primes

Your challenge is to find all Euler Irregular Primes (A prime p is Euler-irregular if it divides an Euler number E(2n) with 0<2n<p−1) under n.

Scoring

Your goal is to use the least amount of bytes.

Answer 23

Approximate Euler's Number

Euler's number (e) is one of the most well-known mathematical constants, with a simple way to approximate it. All you have to do is repeatedly generate a random number between 0 and 1, and add it to an accumulator. Record how many times you have to do this for the accumulator to exceed 1. If you do this over and over again, the average of all the times it takes will approximate Euler's number.

Your task

Write a program that, given a number of iterations as input, approximates Euler's number using the above method and prints the result.

Scoring

This is code-golf, so shortest answer wins. However, if the language you are using does not include a random number builtin, you may exclude from your byte count the code required to import it. For example, if you're writing a Python program to do this, you may assume the random module is already imported.

Example implementation (ungolfed)

import random
acc = 0
res = []
for x in range(int(input())):
    while acc < 1:
        acc += random.random()
    res.append(acc)
    acc = 0
total = 0
for x in res:
    total += x
print(total / len(res))

Answer 24

Count the ways to transform (3)

Your input is an infinite matrix (2d array) of nonneagtive integers where a finite area of the matrix contains nonzero integers. For example:

\begin{matrix} \ddots & \vdots & \vdots & \vdots & \vdots & \vdots & \vdots & \cdot^{\cdot^\cdot} \\ \cdots & 0 & 0 & 0 & 0 & 0 & 0 & \cdots \\ \cdots & 0 & 1 & 0 & 0 & 6 & 0 & \cdots \\ \cdots & 0 & 3 & 5 & 4 & 3 & 0 & \cdots \\ \cdots & 0 & 2 & 0 & 0 & 0 & 0 & \cdots \\ \cdots & 0 & 0 & 0 & 0 & 0 & 0 & \cdots \\ \cdot^{\cdot^\cdot} & \vdots & \vdots & \vdots & \vdots & \vdots & \vdots & \ddots \end{matrix}

A semi-continuous transformation of this matrix is a rearranging of elements that preserves immediate neighbors. For example, we can swap the \$2\$ in the bottom left, and the \$1\$ in the top left corner.

\begin{matrix} \ddots & \vdots & \vdots & \vdots & \vdots & \vdots & \vdots & \cdot^{\cdot^\cdot} \\ \cdots & 0 & 0 & 0 & 0 & 0 & 0 & \cdots \\ \cdots & 0 & 2 & 0 & 0 & 6 & 0 & \cdots \\ \cdots & 0 & 3 & 5 & 4 & 3 & 0 & \cdots \\ \cdots & 0 & 1 & 0 & 0 & 0 & 0 & \cdots \\ \cdots & 0 & 0 & 0 & 0 & 0 & 0 & \cdots \\ \cdot^{\cdot^\cdot} & \vdots & \vdots & \vdots & \vdots & \vdots & \vdots & \ddots \end{matrix}

This is fine, because every number has the same neighborhood counts. That is, we can make a sorted list of numbers and their neighbors, and verify the they are the same:

\begin{matrix} \text{Number} & \text{Neighbors} \\ 0 & 0,0,0,1 \\ 0 & 0,0,0,1 \\ 0 & 0,0,0,2 \\ 0 & 0,0,0,2 \\ 0 & 0,0,0,3 \\ 0 & 0,0,0,3 \\ 0 & 0,0,0,3 \\ 0 & 0,0,0,4 \\ 0 & 0,0,0,6 \\ 0 & 0,0,0,6 \\ 0 & 0,0,1,4 \\ 0 & 0,0,2,5 \\ 0 & 0,0,4,6 \\ 1 & 0,0,0,3 \\ 2 & 0,0,0,3 \\ 3 & 0,0,3,6 \\ 3 & 0,1,2,5 \\ 4 & 0,0,3,5 \\ 5 & 0,0,3,4 \\ 6 & 0,0,0,3 \\ \end{matrix}

(we ignore zeros that have 4 zeros next them, since there are always infinitely many)

TODO: Add example where non-semi-continuous transformation changes the neighborhood counts.

To clarify, semi-continuity is a property of a transformation on some specific matrix.

Your code will take an infinite matrix as input and output the number of (unique) semi-continuous transformations. Two transformations are different if the output is different. So for example swapping two identical numbers is the same as the identity transform (doing nothing). Also, since it's an infinite grid, simply translating the pattern is the same as doing nothing. You can assume the output number will always be finite.

Or in other words: Your code will take an infinite matrix and return the number of matrices with those dimensions that have the same neighbor-list.

Input can be in any reasonable format. You can decide if your input has to have some amount zero-padding or if you always take a square matrix, etc.

Meta

Is this more interesting than version 2?

Answer 25

Alternate indexing

Task

(To do.)

Test Cases

[[1, 2, 3], [4, 5, 6]] => [[1, 4], [[1, 2, 3], [4, 5, 6], [3, 2, 1], [6, 5, 4]]
[[1, 1, 1]] => [[1, 1, 1], [1, 1, 1]]
[[]] => [[]]

Answer 26

Ragged Matrix

A ragged matrix, is a matrix that has a different number of elements in each row. Your challenge is to write a program in any favorable language to find the indices of all occurrences of target in the ragged matrix.

Input:

A list of ragged lists (can be empty) of positive integers and a target range e.g. 56-26. The target range, given 2 positive integers. For languages that do not support this type of list, you can input it as a string representation

You may assume that a<=b

Output:

If a number in the ragged list is within the range or equal to a or equal to b, output the index of the ragged list then the index of the number in that ragged list e.g. 0 4 - The 0 is the first ragged list in the input and the 4 is the index of the number in the first ragged list

Test cases:

[[[1,3,2,32,19],[19,2,48,19],[],[9,35,4],[3,19]],19-53]
->
[[0,3],[0,4],[1,0],[1,2],[1,3],[3,1],[4,1]]

[[[1,2,3,2],[],[7,9,2,1,4]],2-2]
->
[[0,1],[0,3],[2,2]]

You can choose to follow the output format above or output it in the following as well:

[[[1,3,2,32,19],[19,2,48,19],[],[9,35,4],[3,19]],19-53]
->
0 3 0 4 1 0 1 2 1 3 3 1 4 1

0-based and 1-based indexing is allowed

You can output your answers in any way as long as it is distinguishable what the indexes of the number and matrix are

Tags:

code-golf

matrix

ragged-list

Answer 27

Truncatable Primes

A left-truncatable prime is a prime number and when the first digit is removed continuously, the result is always prime.

A right-truncatable prime is a prime number and when the last digit is removed continuously, the result is always prime.

If the integer is only a left-truncatable prime, return left

If the integer is only a right-truncatable prime, return right

Otherwise, return False

Test cases

9137 -> left
9137, 137, 37 and 7 are all prime

5939 -> right
5939, 593, 59 and 5 are all prime

139 -> False
1 and 9 are non-prime, so 139 cannot be truncatable from either way

103 -> False
It contains a 0 digit, which is not prime(even though 103 and 3 are primes)

You may assume that the input will never be both left and right truncatable, so an integer such as 5 will not appear in the input (it is prime and single digit so it is counted as both)

You are allowed to print False as 0 and left as 2 and right as 1

OR

left as 1 and right as 2

Otherwise, you are allowed to use any 3 distinct 3 values/string representation of left, right and False

Tags:

primes

classification

Answer 28

D'Hondt method

the D'Hondt method is a method for allocating seats in parliaments.

Given the Amount of representatives the district you're calculating for is given, and the total amount of voters, and a map or dictionary of every party alongside all the votes they got, you will be asked to give the amount of representatives each party will get from that electoral district as a map or dictionary depending on your language, or as a list/array of whose first index will contain of the party name as a string or char[], then the second the number of representatives as a number (the type is all fine as long as it doesn't have any decimals and is not negative, and their string conversions are something like this: f123 -> "123")

the algorithm: https://plus.maths.org/content/maths-minute-dhondt-method another link: https://en.wikipedia.org/wiki/D%27Hondt_method#Procedure

like as output those are all fine:

return mapOf(
    "Party A" to 4
    "Party B" to 3
)

or

return arrayOf(
    "Party A",  "1",
    "Party B",  "2"
)

you can even give Array as an output as long as you clarify how to get proper values from it somewhere in the answer (in easy terms of course) like:

arrayOf(
    "Party A" to 4
    "Party B" to 8
)

and you can post a snippet like

for(value in output)
{
    if(value::class == Int::class) println(value as Int)
    if(value::class == String::class) println(value as String)
}

The Input will be similiar as such:

• mutableMap<String, Int>
• • "Partyname": Amount of votes it got
• Amount of Voters in that district
• Amount of representatives to be assigned to the parliament from that district

The Output will be something like:

• mutableMap<String, Int>
• • "Partyname": Amount of representatives it got or
• mutableList<String, String>
• • "Partyname": amount of representatives it got in a comprehensible form
• • • Like: [PartyA, 5, PartyB, 10, PartyC, 15] or
• List<List<String, String>
• • Like: [ [PartyA, 5], [PartyB, 10], [PartyC, 15] ]

Those are not strict rules and just a general remind that as long as the input/output is comprehensible it is fine

Answer 29

Tips for golfing in Seriously

I am looking for tips to code in this golfing language Seriously, and was wondering what some of the best/subtle ways for golfing this language is. Thx in advance!

Answer 30

Where is the line

Given a grid consisting of + and a constant \$m\$, change all the + to x, where the center of the + is above the graph \$y=mx\$.
Considering:

• The origin is the bottom-left corner of bottom-left +.
• One unit is the width=height of a plus
• The center of the bottom-left plus is located in \$(0.5, 0.5)\$

Rules

• Input can be given as an iterable, string or a binary matrix.
• Instead of a grid, input can also be the \$height\$ and the \$width\$ of the matrix.
• Output must consist of + and x
• Standard Loopholes apply

Example

[In]:
++
++
0

[Out]:
xx
xx

[In]:
++
++
1

[Out]:
xx
x+

[In]:
+++++
+++++
+++++
+++++
2

[Out]:
xx+++
xx+++
x++++
x++++
+++++

Meta

Did I explain it good enough?