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

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Answer 1

Convert angle to clock time

Answer 2

How normal is this group?

Let \$(G, *)\$ be some group. That is, for all \$x, y, z \in G\$, the following axioms hold:

• \$x * y \in G\$
• \$x * (y * z) = (x * y) * z\$
• There exists some \$e \in G\$ such that \$x * e = e * x = x\$
• There exists some \$x^{-1} \in G\$ such that \$x * x^{-1} = x^{-1} * x = e\$

For some group \$(G, *)\$, we define a subgroup of this as a group \$(H, *)\$ for some subset \$H \subseteq G\$. The trivial subgroups of a group \$(G, *)\$ are when \$H = \{e\}\$ (the identity element of \$G\$) and when \$H = G\$.

For the sake of convenience, we will denote \$x * y\$ as \$xy\$. Let \$N\$ be a subgroup of \$G\$. We say that \$N\$ is normal if, for all \$g \in G\$ and \$x \in N\$, \$gxg^{-1} \in N\$. For any group, the trivial subgroups are normal, and so any group has at least 2 normal subgroups.

For example, let \$G = \{0,1,2,3\}\$ and \$x * y = x + y \bmod 4\$. The subgroups of \$G\$ are \$\{0\}\$, \$\{0, 2\}\$ and \$\{0,1,2,3\}\$, all of which are normal. Therefore, \$(G, *)\$ has 3 normal subgroups.

---

Given a finite group, output a positive integer \$n \ge 2\$ counting the number of normal subgroups of the input. You may take a group as input in any reasonable manner, including but not limited to:

• The set \$G\$ (as a set, list, etc.) along with a black-box function \$* : G \times G \to G\$
• A square matrix representing the Cayley table of the group. You may choose whether to take \$G\$ as a separate input
• A collection of triples \$(a, b, c)\$ where \$a, b, c \in G\$ and \$c = a * b\$ (the order of such a triple is irrelevant, but must be consistent for all triples)
• etc.

This is a code-golf challenge, so the shortest code in bytes in each language wins.

---

Test cases

G
∗ : G×G → G
output

{0,1,2,3}
a*b = a+b mod 4
3

Answer 3

Who needs 8 bits for one character?

Answer 4

Derivative of a product

Answer 5

King of the Cards

Answer 6

Answer 7

Whyte Notation Translator

Answer 8

Tell me how many there are, in Polish

Today, you're going to be writing Polish. No, not Polish notation—Polish, the actual language spoken in Poland.

Given a number and a noun, output a Polish sentence telling me that there are that many of that thing, using the appropriate template below.

The input consists of an integer in the range from 0 to 200, and a string of 1 to 10 lowercase ASCII letters (called the "noun"). You may accept these inputs in any reasonable format.

The output must consist of one of the below output templates, where the number in the template (if any) has been replaced with the input integer, and the word kot in the template has been replaced with the input noun.

Output templates

If the input number is 0, then use the output template

Nie ma żadnych kotów.

If the input number is 1, then use the output template

Jest 1 kot.

If the input number ends with 2, 3, or 4, but does not end with 12, 13, or 14, then use the output template

Są 4 koty.

In any other case, use the output template

Jest 8 kotów.

Note that the special characters used in these templates are:

• ż (in "żadnych") – U+017C Latin small letter Z with dot above
• ó (in the suffix "-ów") – U+00F3 Latin small letter O with acute
• ą (in "Są") – U+0105 Latin small letter A with ogonek

You may output these characters in any reasonably common character encoding (including HTML entities), and you may use combining characters instead of precomposed characters (or even a mixture of the two).

Test cases

0 pomidor -> Nie ma żadnych pomidorów.
1 kwiat -> Jest 1 kwiat.
2 dom -> Są 2 domy.
5 wilk -> Jest 5 wilków.
13 komputer -> Jest 13 komputerów.
24 but -> Są 24 buty.
101 kurczak -> Jest 101 kurczaków.

Do plurals in Polish really work that way?

No, the way it actually works is much more complicated.

This is code-golf, so the shortest program in each language wins.

code-golf string

Answer 9

Find the winning Mormon Bridge card

Mormon Bridge (also called Oh Heck, similar to Oh H***) is a card game played (at least by me) with a standard Rook deck. A standard Rook deck includes cards 1-14 in 4 suits, which are black, red, green, and yellow, and a Rook card. Each round, a card is taken from the deck. It's suit is chosen as "trump." Then, players take turns playing cards. We'll call the suit of the first players card "sub-trump". If the Rook card is played, it wins. If trump was played, the highest trump card wins. Otherwise, the highest sub-trump card wins.

Your Goal

Your goal is to take input for:

• Trump
• Sub-trump
• Cards played

and output the winning card. You may take input in any reasonable manner, swapping suit colors for numbers is fine, as is taking input for all cards played in order instead of separating the first card. code-golf, so shortest answer in bytes wins.

Test cases

(note that input can be taken in any reasonable format, these are written in a human-readable format.)

Trump: Red
Cards played: Red 4, Rook, Black 14, Yellow 7
Output: Rook

Trump: Green
Cards played: Red 14, Red 8, Green 2, Yellow 6
Output: Green 2

Trump: Yellow
Cards played: Red 5, Green 7, Red 12, Black 6
Output: Red 12

Meta

What tags should be on this? Are the rules clear enough?

Answer 10

Is it a valid list?

Answer 11

backwardS_hybriD-snakE_kebaB-cameL_case

Answer 12

Fix my FizzBuzz

Answer 13

Simplify Rubik's Cube Moves

Answer 14

Infinite quote escaping sequence

Posted

Answer 15

Shifted auto-sum

Answer 16

Runs of Ones (What Fun!)

Answer 17

Remove redundant parenthesis

Answer 18

A better Hexagony template

Answer 19

CGCC Rocket Biking

Answer 20

Polyglot Quiz (Cops' thread) Polyglot Quiz (Robber's thread)

Answer 21

Quantise a list code-golf array

In music production, quantisation is the process of "aligning" recorded notes to the beat, to remove the variability caused by imprecise human playing.

In this challenge, we will implement an abstract and approximate version of quantisation, representing notes as runs of positive integers, and using zeroes to represent gaps. The "beat" will be defined as every second note, starting with the first (even indices, 0-based).

Given a list of non-negative integers, insert or remove zeroes such that every run of non-zeroes begins on an even index (using 0-based indexing).

Runs of non-zeroes may not be split or joined together if they weren't already in the input. In other words, a zero cannot be inserted or removed if it only has non-zeroes next to it.

The minimal number of insertion/removal operations must be performed. If a removal is possible, it should be preferred over an insertion.

Test cases

todo

blah blah code golf rules

Answer 22

Zip two arrays

code-golf

Given a list of arrays of the same dimension, zip them at the lowest level. That is, you should output an array of the same dimension, for which the value at each index is a list of the corresponding elements in the input arrays.

For example, for two 3x3 arrays

[[123]  [[abc]    [[[1a][2b][3c]]
 [456] , [def]  →  [[4d][5e][6f]]
 [789]]  [ghi]]    [[7g][8h][9i]]]

and for the three 4x4 arrays

[[19  47  4   69 ]  [[103 67  17  28 ]  [[7   9   48  204]
 [156 120 54  104]   [167 80  99  62 ]   [26  125 230 212]
 [30  70  212 96 ] , [102 165 246 192] , [61  118 137 101]
 [62  80  152 205]]  [118 193 222 65 ]]  [125 247 209 31 ]]
 ↓
[[[19  103 7  ] [47  67  9  ] [4   17  48 ] [69  28  204]]
 [[156 167 26 ] [120 80  125] [54  99  230] [104 62  212]]
 [[30  102 61 ] [70  165 118] [212 246 137] [96  192 101]]
 [[62  118 125] [80  193 247] [152 222 209] [205 65  31 ]]]

Test cases

todo

Sandbox notes

• This feels like something that should've already been posted.
• Name/wording suggestions?

Answer 23

Solve a jigsaw puzzle

Answer 24

Compute the Fabius function

• \$f(x)\$ always takes on rational values at dyadic rationals (i.e. \$\frac m{2^n}\$ with \$m,n\in\mathbb Z\$). It could also be interesting to restrict input to such values, and ask for a rational output.

Answer 25

Convert integer to IEEE 754 float

The task is simple, given a 32 bit integer, convert it to its floating point value as defined by the IEEE 754 (32-bit) standard.

IEEE 754

Here is a converter for your reference.

Here is how the format looks:

The standard is similar to scientific notation.

The sign bit determines whether the output is negative or positive. If the bit is set, the number is negative otherwise it is positive.

The exponent bit determines the exponent (base 2), it's value is offset by 127. Therefore the exponent is \$2^{n-127}\$ where n is the integer representation of the exponent bits.

The mantissa defines a floating point number in the range \$[1,2)\$. The way it represents the number is like binary, the most significant bit is \$\frac 1 2\$, the one to the right is \$\frac 1 4\$, the next one is \$\frac 1 8\$ and so on... A one by default is added to the value.

Now the final number is: $$\text{sign}\cdot 2^{\text{exponent}-127}\cdot \text{mantissa}$$

Test cases

1078523331 ->   3.1400001049041748046875
1076719780 ->   2.71000003814697265625
1036831949 ->   0.100000001490116119384765625
3264511895 -> -74.24919891357421875
1056964608 ->   0.5
3205496832 ->  -0.5625

For this challenge assume that cases like NaN and inf are not going to be the inputs, and subnormals need not be handled, and you may output 0 for the case where the number represented is -0.

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

code-golf

Answer 26

Hexadecimal -> Binary Art

Answer 27

Find a word in the dictionary of all possible words

Answer 28

Generate QR code from string

code-golf binary-matrix

I'm surprised to have not seen anyone doing this particular challenge yet.

The challenge is simple: Take input as a string, your task is to turn it into a QR code.

This challenege originally requires outputting to an image (or any graphical output), but to relax the restrictions down, you only need to output the result as a matrix (or a 2D array). A binary string (with splits between) is also acceptable.

And for sake of simplicity, you will only need to output a 25x25 QR code image (which is the most popular QR code size, I believe). For the input Version 2, the image should look like this:

You may not need to handle empty strings.

Standard loopholes are forbidden.

More resources

• QR Code on Wikipedia
• Reed–Solomon error correction

Answer 29

Integer Bluffing (Still a draft)

king-of-the-hillpython

It's an exciting night at the IGS casino, as a brand new table game is being revealed - Integer Bluffing. Bots from all over the network have come to have a chance at playing the inaugral game, and luckily for you, you just happen to have a seat at the table.

The Rules of Integer Bluffing

At the beginning of a game of Integer Bluffing, each player starts with 20 tokens. A round of Integer Bluffing consists of 4 phases: (i) the deal, (ii) declaring, (iii) reacting, (iv) the showdown

The Deal

Each round, 1 player is chosen to pay an ante, which increases during the game, into the pot. A random integer in the range [1, 8] is then "dealt" to each player. Players only know the true value of their own integer, and once an integer is given to a player, it can't be dealt to anyone else.

Declaring

Starting with the player after the player who paid the ante, each player has the choice to either: a) decline to play the round (fold) or b) put 1 token into the pot and declare what their integer is (play).

Here's the twist - if choosing to play, the player doesn't have to tell the truth about the value of their integer - they can lie and declare they have an integer they don't have. The player also sets a flag whether they say they are bluffing or not - this can also be lied about.

Consider the following game with players A, B, C and D:

Player	Integer
A	4
B	2
C	7
D	3

Assuming Player A paid the ante for the round, player B goes first in the declaring round. Player B sees that they have a 2, which is highly unlikely to win against other integers, so they fold.

Player C sees that they have a 7, so they choose to play the round. Wanting to trick Players D and A into putting a token into the pot, C declares that they have 2, and states they are not bluffing.

Player D sees that Player C allegedly has 2 and that they aren't bluffing. Player D knows that 3 is higher than 2, but knows that Player A might have a higher integer. Therefore, Player D decides to declare 6, not bluffing, in the hopes that Player A folds.

TODO: Continue writing

Answer 30

Triangular polkadot numbers