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.

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Answer 1

Four Candles

There is a tradition in Germany to have an Adventskranz in the run up to Christmas. This is basically four candles. One is lit each Sunday during advent (including the ones from the last Sundays) up until Christmas. This gave me an idea for an ASCII art challenge (we haven't had many of those recently).

The challenge: Reproduce the burning of the candles exactly as shown below.

  ||     ||     ||     ||   
 ____   ____   ____   ____
|    | |    | |    | |    |
|    | |    | |    | |    |
|    | |    | |    | |    |
|____| |___ | |____| |____|

         ||     ||     ||   
  ()    ____   ____   ____
 ____  |    | |    | |    |
|    | |    | |    | |    |
|    | |    | |    | |    |
|____| |___ | |____| |____|

                ||     ||   
         ()    ____   ____
  ()    ____  |    | |    |
 ____  |    | |    | |    |
|    | |    | |    | |    |
|____| |___ | |____| |____|

                       ||   
                ()    ____
         ()    ____  |    |
  ()    ____  |    | |    |
 ____  |    | |    | |    |
|____| |___ | |____| |____|

                       ()
                ()    ____
         ()    ____  |    |
  ()    ____  |    | |    |
______ |___ | |____| |____|

The rules: Very simple really...no input required, any amout of trailing newlines or spaces alowed as long as the output looks exactly as above. Please feel free to show each stage as a different frame and clear the screen between each but this is not a requirement. Simply printing (or retuning from a function) what is shown above is fine. Oh and also, this is ASCII art...printing or returning a list of lines is not good enough.

This is code golf. The shortest answer in any language will earn respect and I'm sure some upvotes. There will be no accepted answer so feel free to join in. The more languages the better no matter how long the answer is, as long as it is a best effort to make it as short as possible (golfed).

Answer 2

Make the cheapest cut

Answer 3

Find the box by its corners

Answer 4

Denoise a image code-golf

There are various de-noising algorithms available. This question focuses on a specific one that preserves sharp edges but is also very simple to implement.

Take 2 parameters, r and k, and a grayscale image.

For every pixel, draw a r by r square around it and select all pixels inside.

 r=1   r=3     r=5
              #####
       ###    #####
  p    #p#    ##p##
       ###    #####
              #####

Find the k pixels in this area that are closest to the source pixel in terms of absolute color difference.

Replace each pixel with the median of the k closest pixels in it's area. Include the pixel itself in it's area. If there are less than k closest pixels take all of them. This can happen for pixels near the edge.

Note: If r==0 or k==1 this will return the image unchanged

r is always odd.

Test Cases

In    K    R    Out
-------------------
000             000
010   1    1    010
000             000
-------------------
000             000
010    3    3   000
000             000
-------------------
000             000
010    3    3   010
100             100
-------------------
000             000    000
010    5    3   010 OR 010 since the median is tied
101             000    101
-------------------
12345           
23451
34512  5    5
45123
51234
-------------------

IO

Take input as either a image file or as a 2 dimensional array of integers between 0 and 255. Output in the same format.

Answer 5

Is It a Flat 3D Quadrilateral?

code-golf decision-problem geometry 3d

Your task is to write a program or function that, given a collection of four 3D points with Cartesian coordinates, outputs whether the shape formed by connecting those points is a flat 3D quadrilateral (i.e. all the points are coplanar).

Rules

• The input will always have 4 points.
• Each shape will be formed by connecting the points with lines in the order they were given and then back to the first point. You may assume that no two of these lines will intersect each other and that no three consecutive points will be collinear.
• For each point \$(x, y, z)\$, \$x\$, \$y\$, and \$z\$ will all be integers within the range \$[0,8]\$.
• You may choose any two distinct values to represent a truthy and falsy output, as long as it is consistent. Input can be in any convenient format.
• This is code-golf, so the shortest code in bytes wins.

Test Cases

Input	Output
(0, 0, 0) (0, 1, 0) (1, 2, 0) (1, 0, 0)	true
(0, 0, 0) (0, 1, 0) (0, 0, 1) (1, 0, 0)	false
(0, 0, 0) (1, 0, 0) (1, 1, 1) (0, 1, 1)	true
(0, 1, 2) (3, 4, 6) (7, 8, 5) (4, 3, 2)	false
(1, 1, 1) (2, 2, 2) (1, 3, 2) (2, 4, 5)	false
(0, 4, 8) (4, 8, 4) (8, 4, 0) (4, 0, 4)	true

Meta

• Any additional test case suggestions?

Answer 6

Find the representative submatrix

Answer 7

Rolling a 1x1x2 block

Answer 8

Write a program that prints a program that's almost quine.

Answer 9

Balanced Candy Distribution

There are 4 piles with 12 pieces of candy each, for a total of 48 pieces, and there are 12 kids to split that candy with, each kid will receive exactly 1 piece of candy from each pile, each piece of candy has a unique number on it, from 0 to 47, the candies with numbers 0 through 11 are on one pile, candies number 12 through 23 are on another, candies 24 through 35 are on a pile, and the last pile is candies 36 to 47. Candy #0 tastes amazing, and candy #47 tastes not so great, so to make it fair, each kid’s 4 candies should add up to the same number (which should be 94), there is an issue though, there are an unknown number of different flavors of candy, completely independent of their tastiness, and it would be unfair if Timmy was to, by bad luck, have all his 4 pieces of candy end up being cinnamon flavored, so, we introduce the idea of “Unfairness points”. For each kid, if we match each of their four candy pieces to their other three candies, for each pairing if both candies are the same flavor, we add one unfairness point, to illustrate this, let’s imagine a smaller example, with only four kids and 16 candies, if Timmy got 4 cinnamon candies, Laura got 1 cinnamon candy, 1 vanilla candy, and 2 chocolate candy, Johnny got 2 vanilla candies and 2 caramel candies, and Sam got 3 cinnamon candy and 1 strawberry candy, this arrangement would receive 12 unfairness points: 6 from Timmy, 1 from Laura, 2 from Johnny, and 3 from Sam.

Your code must output the arrangement that satisfies the two restrictions set forth in the beginning (each kid receives a single candy from each pile, and that for each kid all of their four candies add up to 94) that has the fewest unfairness points, if there is more than one arrangement that is tied for least number of unfairness points, you must output the list of all of those arrangements given a list of all the candies. This input could be formatted in any way that is convenient, but preferably something resembling a list of strings, where the index is the number of the candy and the string is the flavor, for example, in python, a valid input format would be

[“Chocolate”,“Chocolate”,“Chocolate”,“Vanilla”,“Chocolate”,“Apple”,“Chocolate”,“Vanilla”,“Caramel”,“Chocolate”,“Vanilla”,“Chocolate”,“Apple”,“Apple”,“Caramel”,“Chocolate”,“Vanilla”,“Chocolate”,“Apple”,“Sour”,“Chocolate”,“Chocolate”,“Vanilla”,“Chocolate”,“Apple”,“Sour”,“Pear”,“Pear”,“Caramel”,“Vanilla”,“Vanilla”,“Vanilla”,“Apple”,“Sour”,“Chocolate”,“Chocolate”,“Avocado”,“Apple”,“Sour”,“Pear”,“Pear”,“Chocolate”,“Chocolate”,“Chocolate”,“Vanilla”,“Chocolate”,“Vanilla”,“Caramel”]

Or it could also be already separated into the piles

[[“Chocolate”,“Chocolate”,“Chocolate”,“Vanilla”,“Chocolate”,“Apple”,“Chocolate”,“Vanilla”,“Caramel”,“Chocolate”,“Vanilla”,“Chocolate”],[“Apple”,“Ap...

Or it could include the number itself, if you wanted

[[0,“Chocolate”],[1,“Chocolate”],[2,“Chocolate”],[3,“Vanilla”],[4,“Chocolate”],[5,“Apple”],[6,“Chocola...

The output can be given in any way that makes it easy to interpret what the numbers of the candies each kid should get, for example, in python, an output like

[[0,19,30,45],[9,14,28,43],[5...

Is totally fine, and anything that is easy or understandable like that is fine.

This is code-golf and so lowest bytes wins

---

Sandbox questions:

• English is my second language, is this written clearly enough?
• Would it be better if it was generalized? As in "There are N piles with C pieces of candy each, for a total of N*C pieces, and there are C kids to split that candy with, each kid will receive exactly 1 piece of candy from each pile..."
• Any other thoughts?

Answer 10

Wordle games without repeating letters

Given a word list, find all sets of five words of five letters each, such that the words of each set have 25 distinct letters in total.

This challenge was inspired by this video by Matt Parker.

Example

TODO

Rules

• Standard I/O rules apply.
• Words contain only lowercase (or alternatively, uppercase) alphabetic characters.
• You can assume there are no empty words (i.e. words of length zero).
• The input can contain words that cannot belong to any set that satisfies the property, such as words with less then five letters, words with more than five letters, and words with repeated letters.

### Scoring

This challenge wants to be an experimental mix of code-golf and fastest-code.

If your solution has:

• a time complexity of \$\Omega(f(n))\$ (see Big Omega notation) where \$f: \mathbb N \to \mathbb N\$ is a function of the form $$f(n) = (\log_2 \log_2 n)^{k_{-2}} \cdot (\log_2 n)^{k_{-1}} \cdot n^{k_0} \cdot 2^{k_1} \cdot 2^{(2^{k_2})} \cdot \ldots $$ where \$n\$ the the total number of the letters of the words in the input;
• a length of \$x\$ bytes (or whatever unit of measurement is commonly used in the language of your choice);

then the score is \$f(x + 4)\$. Lowest score wins!

Notes

• obviously, infinitely many terms \$k_i\$ can be \$0\$;
• terms with three or more \$\log\$ (e.g. \$\log_2 \log_2 \log_2 n\$) cannot be used in function \$f\$ because they could be used to arbitrarily lower the score, unless we introduce further complex scoring rules (and most probably they won't be used as a real lower bound).

Scoring example

If your solution has a length of \$37\$ bytes, and it has a time complexity of \$\Omega(n^5)\$, then it has a score of \$(37+4)^5\$.

Edit: scoring rules postponed for a future challenge

Answer 11

Tell 32-bit from 64-bit with most disallowed bytes

Decide an integer N. Take an array of length N, and output a x86 opcode, which when running, reach different position after leaving the opcode you provided.

• No bytes given in input is allowed in your output.
• You'll be in Ring 3, so some x86 features can't be used.
• You can destroy all available registers, including XMM, x87, etc.
• You can assume 4096 bytes of available stack under stack pointer.
• It's not necessary a jmp. Other ways to reach different position are fine.
• The destination should be in 256 bytes before your code or in 256 bytes after your code. jmp .+0xEBEBEBEB is not allowed unless your output is at least ~336859924 bytes.
• Each destination should have at least 2 bytes of space to fit a jmp short instruction.

Here is a possible program with N=0:

([])=>[0x66, 0x40, 0x3D]

Assuming this program is loaded into 0, then in 32-bit mode, it goes to 7; in 64-bit mode, it goes to 5, both of which have enough space.

This is an example with N=1:

([x])=>x==0x66||x==0x41||x==0x3D?[0x24,0x00,0x40,0x74,0x74]:[0x66,0x41,0x3D]

Largest N wins.

Answer 12

Title Case (WIP)

string code-golf

Input a string with letters and spaces, input a set of mirror words. Output a string which is title case of the input string that follow the following rules:

1. Cases is unchanged for any words already contains uppercase letters;
2. Cases is unchanged for any words in the set mirror words AND is not the first word;
3. For all other words, the first letter is changed into uppercase

The set mirror words is an input to your program / function. Here are mirror words used in testcases:

["a", "an", "and", "as", "as", "at", "but", "by", "for", "if", "in", "nor", "of", "off", "on", "or", "per", "so", "the", "to", "up", "via", "yet"]

Testcases

Input -> Output
the sun and the moon -> The Sun and the Moon
jQuery tutorial using jQuery plugins -> jQuery Tutorial Using jQuery Plugins

Answer 13

A map maps keys(string) to values(string). Basic operations includes:

• Set. Given a key and a value, store it.
• Get. Given a key, get the last value stored into this key, or ""(empty string) if nothing ever stored into.

For some reason, sometimes keys looks same but need to refer to different object. Therefore, color is introduced. Provided keys is therefore splitted, and to get colored key, color each part of keys, and concat them.

For example, say a is colored red, then

• a is \$\color{red}a\$
• aa is \$aa\$
• a a is \$\color{red}{aa}\$
• ab is \$ab\$
• a b is \$\color{red}{a}b\$

Therefore, another operation is

• Color. Given a keypart, resign its color. Color is a non-negative integer and default to 0.

Shortest code in each languages wins.

Test cases

[[GET, "a"],         // ""
 [SET, "a", "1"],
 [GET, "a"],         // "1"
 [COL, "a", 1],
 [GET, "a"],         // ""
 [SET, "a bb", "2"],
 [GET, "a b b"],     // "2"
 [COL, "a", 0],
 [GET, "a"]]         // "1"

Answer 14

Solve the "/" puzzles from Taiji

Spoilers for the game Taiji, it's really good you should play it

Taiji puzzles consist of a rectangular grid, a solution consists of setting each square to either on or off:

####
#...
##..

However, not every solution is correct, a puzzle can contain any number of colored slashes, here represented by numbers:

....
1...
..1.
....

A shape is defined as a contiguous area that all has the same state. (either on or off). Areas with the same color slash must have the same shape, but it may be rotated (but not mirrored). For example, if you have this:

1..1.
.22.1
1..1.

A solution would be:

.#.#.
##..#
.#.#.

Note that all 1s are a single square while both 2s are a T shape, in this case in opposite colors.

Note that the number must be in the same place in every shape, so if you have this puzzle:

.....
1..1.
.....

This would Not be valid:

#..##
..##.
#..##

Because one 1 is in the tip and the other is in the tail.

If the numbers are different the shapes must be different. However, they count as different if the number is in a different part of the shape.

A shape can contain multiple numbers. If it contains the same number twice that means the shape must be irrationally symmetric.

Your challenge is: Given a number, output a possible solution. Note: There will always be at least 2 possible solutions, since the inverse of any valid solution is also valid.

Test Cases

Note many of these have many valid solutions.

1..1.            #..#.
.22.1        --> ....#
1..1.            #..#.

....              ##..
123.          --> #.##
....              #.##


...               #.#
111           --> #.#
...               #.#

1.22.1            ##..##
......            ######
2....2        --> .####.
2....2            .####.
......            ######
1.22..            ##..##

3....             #####
11211         --> ..#..
3....             #####

....              #.#.
111.          --> #.#.
....              #.#.

You may take input as a 2d list of numbers, and use any constant value to represent a cell that does not create a hint (eg. 0). For output you may also use any 2 constant values to represent on and off.

Answer 15

Best Iterated Prisoner's Dilemma

Answer 16

Optimize your score on a biased multiple choice test

In a multiple choice test, sometimes, by chance, multiple questions in a row will have the same answer. Some of my teachers dislike this, and will change questions to ensure there are never more than \$n\$ of the same answer in a row.

In this challenge, for each question in a test, you'll be given a set of four confidence values from 0 to 1, which sum to 1. These represent the odds of each choice being correct (for example, [0.1, 0.6, 0.2, 0.1] if you're 60% sure that B is correct, 20% sure C is correct, and 10% sure either of the others could be right). You'll also be given a positive integer n, the maximum number of same-answer questions in a row.

Given this information, you must output the set of answers that would give you the highest estimated score.

Answer 17

Pushing boxes away but fastest-algorithm

I'll accept first fastest algorithm and then this challenge turns into restricted-complexity code-golf.

Sandbox Notes

• Some options are listed in comment

Answer 18

A randomly colored walk

code-golf random color

Given two inputs, a distance \$d\$ and a number \$n\$ output \$n\$ random colors which each have distance \$d\$ from the previous.

Background

A random walk is a path which is defined by choosing a random direction and (usually) fixed distance to go at each step. We will be taking a random walk through the RGB color space using Euclidean distance as our metric.

The challenge

For this challenge you will take two inputs, \$n\$ and \$d\$. Let \$n\$ be the number of colors to output, this will always be an integer \$1 \leq n\$, and \$d\$ be the distance between consecutive elements, which will always be \$0 \leq d \leq 128\$. You may additionally assume that \$d\$ is an integer.

For each consecutive pair of elements \$(r_1, g_1, b_1), (r_2, g_2, b_2)\$ of the \$n\$ element sequence output, it must be the case that all values are between 0 and 255 inclusive (or \$[0,256)\$ for floats), and the distance between elements must be within 1 of d, that is \$|\sqrt{(r_1-r_2)^2+(g_1-g_2)^2+(b_1-b_2)^2} - d| < 1\$. This should allow one to restrict their output to integers if they so choose. The walk need not be uniform, but it does need to be random. The starting point of the walk should be random as well.

Standard i/o rules apply, input and output can be in any reasonable format. Graphical output is allowed (and encouraged, though I doubt it will be golfy to do so) so long as the order of the sequence is clear.

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

Test cases

For these test cases input is in the order \$n,d\$ and output is \$(r, g, b)\$ as integers. These are some possible results.

5, 5 -> (81, 60, 243), (81, 57, 239), (76, 60, 240), (80, 62, 241), (84, 60, 243)
4, 10 -> (163, 89, 77), (162, 83, 85), (166, 75, 79), (166, 82, 87)
4, 50 -> (212, 36, 232), (247, 1, 239), (220, 44, 243), (217, 81, 209)

Answer 19

Related

Play chess. You can't see the current board, and can only memory two bytes.

Each turn, you're given your current state(initially 0) and opponent's move(a special value if first move in the game). You then output a list of [moves,state] pair, and the first valid one will get used. If no valid move, then you automatically resign.

Aim is obviously win as many games and lose as less as possible.

king-of-the-hill chess

Answer 20

4D rotation matrix to quaternions

Answer 21

Ternary 2-input logic gate

Objective

Given an expression of a ternary 2-input logic gate, pretty-print its truth table.

Ternary logic and ternary operators

L, E, and G are the truth values of the ternary logic dealt here. They correspond to Haskell's LT, EQ, and GT.

The expression can have two free variables, hence "2-input".

There are four operators that the expression can have: min, max, compare, and mappend. (Again, from Haskell.) Their truth tables are:

min|L E G
---+-----
L  |L L L
E  |L E E
G  |L E G

max|L E G
---+-----
L  |L E G
E  |E E G
G  |G G G

compare|L E G
-------+-----
L      |E L L
E      |G E L
G      |G G E

mappend|L E G
-------+-----
L      |L L L
E      |L E G
G      |G G G

where the first column is for the first argument and the first row is for the second argument.

I/O format

The input format shall be a nonempty binary tree whose branches are the operator and whose leaves are the free variables and the truth values.

The output format shall be like this:

 |L E G
-+-----
L|? ? ?
E|? ? ?
G|? ? ?

where ? is filled with appropriate truth values represented by L, E, or G. Again, the first column is for the first argument and the first row is for the second argument.

Examples

Let the free variables be P and Q in sake of demonstration.

Given P compare (E compare Q), the truth table is:

 |L E G
-+-----
L|L L E
E|L E G
G|E G G

Given (P min Q) compare (E compare (P max Q)), the truth table is:

 |L E G
-+-----
L|L E E
E|E E E
G|E E G

Given ((E compare (P max Q)) compare (P min Q)) mappend (P compare (E compare Q)), the truth table is:

 |L E G
-+-----
L|G L E
E|L E G
G|E G L

Given Q mappend P, the truth table is:

 |L E G
-+-----
L|L L G
E|L E G
G|L G G

Answer 22

Floating-point numbers have errors in addition, oh my!

Given two IEEE double-precision floating-point numbers \$x\$ and \$y\$, output the most accurate IEEE double-precision floating-point approximation of the error that would be caused by performing the floating-point addition \$x + y\$.

As a reminder, an error is defined as the approximation subtracted by the exact value.

The inputs must deal with denormal numbers and the negative zero as well. However, infinities and NaNs fall into don't care situation.

If the output is zero, its sign doesn't matter.

Answer 23

A Fine sequence with fine interpretations

Answer 24

Making one shape out of dissections of another

Answer 25

Find the sum of the sub-list with the largest sum

Challenge

Given a list that contains an integer, a sub-list is a contiguous non-empty sequence of elements within that list.

For example, the list \$[1, 3, -2, 5, -6]\$, has some sub-lists \$[1]\$, \$[3, -2]\$, \$[3, -2, 5, -6]\$, etc.

Your job today is to find the sum of the sub-list with the largest sum.

For example \$[1, 3, -2, 5, -6]\$, the sum of the sub-list with the largest sum is \$7\$, the sub-list with the largest sum is \$[1, 3, -2, 5]\$.

Specification

• Input / Output can be taken in any reasonable format, taking a list of numbers and returning a number, which is the sum of the sub-list with the largest sum
• The input array is guaranteed to have at least one element.

Testcases:

[1, 3, -2, 5, -6] -> 7
[-2, 1, -3, 4, -1, 2, 1, -5, 4] -> 6
[-3, -6, -8, -1] -> -1
[5, 4, -1, 7, 8] -> 23

This is code-golf, so shortest answer (in bytes) wins!

Answer 26

Canonical form of a cubic Bézier curve

Answer 27

Draw Parcly Taxel's cutie mark

Answer 28

Generating all possible equations with 10 characters

Answer 29

Generate number from given range

Answer 30

The topology of origami