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

Two functions with same input/output, with largest difference in bytes.

This challenge is a terrible idea. Don't try submitting it or anything similar!

Provide two functions with the largest difference in bytes. (These two functions will be referred to in bold italics to distinguish them from built-in functions available in your language in the rules below.)

Rules:

1. Both functions must take an input and must produce an output. The input to and output from both functions must be identical.

2. Both functions must be explicitly named. The function names must have the same byte count.

3. You may not define any other functions.

4. If you use a built-in function your language provides, it must be used with the same number of parameters in each of the functions.

5. You may use string/numeric literals or any built-in constants, but you must use exactly the same ones in both functions.

6. You can define variables, must you must use the same variable names in both functions.

7. You can use comments, no-ops, and the equivalent, but they must be the same in both functions.

8. Both functions must contain the same amount of whitespace (or equivalently, don't count whitespace at all.)

9. You can import libraries/packages and the equivalent, as long as you import the same ones for both functions.

10. You can use pre-processor directives as long as they are the same for both functions.

If any of these rules mean your language cannot compete, so be it.

Not really sure how to tag this. A little bit of code-golf code-bowling and restricted-source.

Answer 2

Quiet QR

Your mission, should you choose to accept it is to infiltrate the top secret HQ of the Big Bad Evil Guy (TM) and extract information on their latest evil scheme saved in the file Plan.txt.

The target PC is isolated from any and all network connections, and you can't physically connect anything to it. The server room is equipped with sound sensors that will detect key presses.

Your tools are restricted to a mobile phone equipped with a QR code reader. Your recommended course of action is to write a code on the target machine that will display the file content as QR code.

You are to complete the mission with the least number of keystrokes as to minimise the sound generated by the mechanical keyboard.
It is advisable not to use languages that require unicode characters as entering one character will require multiple key presses (Eg:þ = Alt+0254) is considered 5 keystrokes.

You are to assume that the machine will have its terminal open and ready for input at the root directory of the system (C:\> or /).

All programming languages can be accessed directly from root folder. The target file is on the root folder.

Javascript is available as command line executable named js usable as (js filename) and prints output.

Image viewer is called view and usable as (view imagefile) [Extension is not needed]

Possible ways of output:

1. An image containing the QR code

2. ASCII art depicting the QR code using characters like █ ▄▀

3. Or any form readable by any standard-issue QR code reader

4. Other formats of 2D barcodes are accepted on the condition of being readable by a standard reader.

Example Solution for batch file:

copy con a.bat
open file Plan.txt
echo █ ▄▀
^Z
a

=59 keystrokes.

The symbols are 4 keystrokes each:

• ▀ Alt+991

• █ Alt+987

• ▄ Alt+988

^Z as Ctrl+z and is considered 2 ketstrokes (F6 is considered one).
New lines and spaces are one keystroke each.
Capital letters are 2 strokes (Shift+c).
CAPITAL words are one keystroke added to the length of the word (Shift+capital).
No need to clean the screen at the end because the evidence will be erased by a Micro-EMP device that will disable the machine.

Answer 3

Projective related points

code-golf geometry decision-problem math

Points A, B, C, D and A′, B′, C′, D′ are related by a projective transformation if their cross ratios are equal.

Given A, B, C, D four ordered points on a line, their cross ratio is defined as:

\$\displaystyle\frac{distance(A,C)\times distance(B,D)}{distance(A,D)\times distance(B,C)}\$,

where \$distance(A,C)\$ is the Euclidean distance between points A and C.

Challenge

Given a set of eight points, say if yes or no the set can be splited into two subgroups (each subgroup with four points) where the two subgroups are related by a projective transformation.

Input

A set of 8 points, each point defined by its Cartesian coordinates (integer coordinates).

Output

Either a specific true output (true, 1, yes, ...) or a specific false output (false, 0, no, ...).

Example

{(10,100),(25,100),(2,63),(2,33),(31,100),(2,13),(2,3),(17,100)} --> true
with subgroups:
{(10,100),(25,100),(31,100),(17,100)} 
and 
{(2,63),(2,33),(2,13),(2,3)}

{(45,54),(8,23),(8,8),(8,29),(27,30),(15,14),(9,6),(8,15)} --> true
with subgroups:
{(8,23),(8,8),(8,29),(8,15)}
and 
{(45,54),(27,30),(15,14),(9,6)}

Hint (no need to use division or square root)

In order to avoid floating points, you can use the fact that points A, B, C, D and A′, B′, C′, D′ are related by a projective transformation implies:

\$distance^2(A,C)\times distance^2(B,D)\times distance^2(A',D')\times distance^2(B',C')\$

equals

\$distance^2(A',C')\times distance^2(B',D')\times distance^2(A,D)\times distance^2(B,C)\$

Rules

• The input and output can be given in any convenient format.
• No need to output the two subgroups.
• No need to handle the case when at least two points in the set are the same.
• No need to check the fact that the four points in each subgroup are aligned.
• In your submission, please state the true and the false values.
• 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 4

A function to traverse an array and re-generate the same array

We take an array, then write a function that will traverse the array and generate the array in a format given in the example below.

For example, given the array:

Array

(

  [0] => Array
  ( [name] => Tom
      [age] => 32
      [key] => Array
      ( [0] => abc
          [1] => def
          [2] => efg
          )
      )
  [1] => Array
  ( [name] => Jim
      [age] => 30
      [key] => Array
      ( [0] => abc
          [1] => def
          [2] => efg
          )
      [address] => Array
      ( [0] => Array
          ( [state] => CA
              [country] => US
              )
          [1] => Array
          ( [state] => NY
              [country] => US
              )
          )
     )
)

Output should be:

User: 0
 name: Tom
 age: 32
 key:
  0: abc
  1: def
  2: efg
User: 1
 name: Jim
 age: 30
 key:
  0: abc
  1: def
  2: efg
address:
0:
 state: CA
 country: US
1:
 state: NY
 country: US

Challenge rules:

• You can assume array can be multidimensional
• The array can also be array of cars, schools, districts etc.
• The preferred output is in json format
• Indentation for the output is a simple json format

code-golf

The function will be tested with any sort of multidimensional arrays for speed of execution

Answer 5

Pyramid of Bots

king-of-the-hill

In this game, your bot is trying to get as high off the ground as possible. However, it can only stand on top of other bots, which are trying to get higher, too!

Overview

Your bot should be a Javascript function. It's return value should tell the program if the bot should move left, move right, or jump. Every bot starts out on a 2 dimensional grid, with a width and height set by (botCount * 2) + 1. Bots are placed on either side of the center space, and every other bot is spaced 1 apart from any other bot. They all start at y=0, and far left is x=0.

Gravity

If there is no bot on top of your bot, it can return the value jump. When a bot jumps, it moves 1 square up. If at any point in time there is nothing under the bot, it moves down 1. A bot cannot return jump if nothing is under it. If your bot is on top of another bot which moves left, your bot will fall.

Function params

Your function has 3 parameters: dirs, height, and map. The array dirs contains four boolean values, representing if there is a bot or arena border: below, to left, to right, above. The parameter height is an array with 2 elements: your height, current winner's height. The map array contains the height/width of the array, and then the amount of turns left in the game.

Running the game

In one game, the bot function will be run 800 times. Each of these is a turn. Your bot should return jump, or a direction. The bot can only move in a direction if there is no bot currently there. The two directions are left and right. Standard loopholes are not allowed (when are they ever allowed??), and the bot who wins the most out of 1000 games is the winner.

Answer 6

My Ribosomes Got a Firmware Upgrade

code-golf bioinformatics

---

So all of the Apple iBosomes in my body have been updated to RibOS 4.0 now… while I appreciate the additional optimizations that were added, unfortunately for me they've dropped support for the legacy mRNA API.

So since my RNA Polymerase library still needs to return strings in the format AUUCGGUCAAAGU for the code still using it, I'll need to add some code to the getBasePairs() method to translate it from the new API.

Challenge

• Your input will be a string in base64 (because codons are exactly 6 bits) representing the genome.
• You should output a string with the equivalent RNA base pair sequence:
  • 00 becomes A.
  • 01 becomes G.
  • 10 becomes C.
  • 11 becomes U.
• All languages are allowed.
• Your I/O must be in these exact string formats, even if they're small enough to encode as integers.
• The shortest answer in bytes wins.

Answer 7

Trilateration

Intro:

Similar to Trilaterate your position with a small twist.

In a n x m array,

Original Problem:

You will be given a list of (x,y,d) as input, where d is the distance of your position from the point (x,y). Using this we can find our position.

................

In the above problem, d is the exact distance from the respective point.

In this problem, due to some error, we know that the distance is actually the maximum distance from the respective point. Because of that, instead of a single point, we will get a small area of our position. Objective is to get that area.

It should be in the format(a function):

f(list,n,m):
  #your code here
  return #list of all indices where you may be.

What's returning should be a list of points (x,y) with 0<=x<=n,0<=y<=m.

In case there is no solution return an empty list. The winner will be the fastest code. In case of a tie shorter code wins. The time taken will most likely depend on n,m and list of points.

Answer 8

The goal of this challenge is to make an interpreted language that can print anything! The format of the language needs to be

[command eg: print] [args];

You have to use regex, even though it is not the typical way to write a language, to avoid people finding loopholes. Your interpreter also needs to ask for a file to open to interpret; example input file prompt:"File to interpret: "

Some tests to try:

print Hello World;


print This is a very very very very very long test;

ktrgjkfgjk;

print hi

If your interpreter runs these tests correctly, you can submit your interpreter.

Notes:

Do not just cut off the print!

If the command given does not exist, or if semicolon not present, print "Error"

This is code-golf so the lowest byte count + working code wins!

Answer 9

Name: Create a Programming Language

Tags: code-bowling, and cops-and-robbers

Cops:

The cops must design a programming language that takes in the contents of the program from a default I/O method, and do something.

Rules:

• The program must not print anything to STDERR
• The program must be able to output to STDOUT with certain program contents of your choice
• The program must be able to calculate any function up to \$f_{\omega}(n)\$ where f is the fast-growing hierarchy. In other words, it needs to be able to evaluate any primitive-recursive statement.
• There cannot be a way to execute commands in other languages (for example, if there is a command in your programming language that can execute Python code based on the argument, that would be cheating)

Since there are tons of loopholes, whether or not the answer is valid is up to me (and also, standard loopholes are also not allowed).

Robbers:

Your job is to make the same compiler (which does the same thing with the same commands given as the equivalent cop answer), with more characters. The programming language may be different.

Standard loopholes aren't allowed, and whether an answer is valid or not will be judged by me.

As always, since this is code-bowling, aim for the most bytes!

Answer 10

Win 2048

Win 2048. You can decide where to summon block of 2(no 4), and how you move. The output would be [place, place, move, place, move, ..., place, move](finally you reach 2048).

Shortest code win.

SN: Similar to Play a perfect game of 2048 ?

Answer 11

Coprimes upto N (Performance Edition)

There is this question: Coprimes up to N

Most of the answers there take way to long for larger numbers.

So, your task is to find all the coprimes of a number n (gcd(n,coprime)==1) up to nas fast as possible.

Scoring

Score=Largest n for which your code will output in less than 10 seconds on my laptop. Provide instructions to run it on my machine.

Highest score wins.

I will put the specs of my pc, anything else needed?

Answer 12

A Quine that Grows!

Challenge

Create a quine that, when run, outputs itself but copied larger in the next one. The output should be able to be run, and get larger each time the output is run. The output must consist only of characters from the original quine!

EX:

abc //original
abcabc //output

or

abc //original
aabcc //output

What not to do

abc //original
abcgef //output

abc //original
abcoooooooooooo //output

An example I created

Try it Online! It replicates pretty fast if I do say so myself!

Points

This challenge is meant to be a codegolf, but also emphasize on how fast it replicates. So perhaps something like the speed at which it gets bigger divided by the number of bytes.

I really don't want loopholes like just repetitively adding characters to a section of the code, making infinite loops, and things of the like.

Any input on how to make this a good challenge? I'm open to suggestions!!!

Answer 13

Just idea. Not sure what to do exactly.

Evolutionary Golf

code-golf answer-chaining restricted-code

Make simple (not golfed at all at first) code for (some program) with language (something).

Now, change a little bit (maximum 3 byte) of code to make it shorter.

Altered code must work properly (this is how evolution work).

(Maybe here will be starting code).

Sandbox

First. What program would be best? For example, 'Hello World' program is not proper, because it is too short, and can't golf that much.

Second. What language would be best? Esolang like BF? Or something like C?

Answer 14

Print all the commands

META Just a rought idea, needs to be worked out. code-golf

Write a program that prints all the keywords and commands that are available in your langauge when you do not import/add anything

Details

• require full program or standard code-golf?

Answer 15

Here's a challenge I'd like post because I'm curious to see what people will come up with. It's a bit of an anti-code-golf question because the code should look normal.

Is it clear what the constraints? Did I miss anything?

---

Introduction

Write a piece of unsuspicious code that does the following:

Let's say you've written a parser that parses it's input line by line and somewhere in your code is

find_string(line, "[start]", "[end]") // returns string between [start] and [end]

This program, when given it's own source code plain text as input, will match that line (twice actually); but we don't want that. It should still parse what it was designed for but not match any line of it's own source code.

Rules

• It's preferred that your code makes it obvious that one of it's intended uses is to parse (and not match) itself. This is so anyone 'refactoring' the code will not accidentally undo the trick that made it work.
• Your source code as input will be reduced to a single line.
• Your program should be able to handle large input (~10mb) and perform reasonably (for your chosen language).
• Your program does not need to parse the input line by line but that just seems like something reasonable code would do.
• Points are awarded for code that looks like a normal parser and contains as little assumptions about the input as possible. Bonus points for solutions that contain the start and end delimiters in that order.

Easy solutions are to swap the start and end token arguments or to pre-treat the tokens in some way but that would look suspicious. Someone will come along and refactor your code and break the 'trick'.

I'm interested in reasonable solutions because this is a reduction of a real life problem.

Example Input and Output

• Input lines may or may not contain [start] or [end], only return it in the output when it occurs in a pair.
• Input lines will never contain more than one pair of [start] and [end] tokens.
• Input lines may contain additional content before [start] or after [end]
• Your source code plain text will be inserted at a random line in the input.

Input #1:

[start]hello[end]
<<your source code plain text>>
dont output this[start]world[end]

Output #1:

hello world

Input #2:

lorem[start]i solemnly[end]
[start]false start
[start]swear[end]
ope, sorry just passing through
this is not the[end]
[start]that i'm up to[end]ipsum
[start]no[end]dolor
<<your source code plain text>>
[start]good[end]

Output #2:

i solemnly swear that i'm up to no good

Answer 16

Title: Transposition

** The challenge **

Given a set of notes (as a string, or a list, or any other reasonable input - but as letters and accidentals, not a numerical equivalent), the key those notes are in, and a target key; output the notes transposed into the new key. Some of the notes may not exist in the scale for the given key (e.g Eb in the key of C).

** Inputs **

The complete set of input notes for this challenge will use the English naming convention, and so are as follows:

Ab,G##,A,A#,Bb,B,C,C#,Db,C##,D,D#,Eb,E,F,F#,Gb,F##,G,G#

where "b" represents a flattened note (down one semitone per b), and # represents a sharpened note (up one semitone per #). Theoretically all notes can be extended further with more #s and bs; but for the purposes of this program that won't happen beyond what is already given.

** What is transposing? **

Transposing a song involves "moving" the song into a different key, by finding the equivalent note of the scale in that key.

We will assume Major scales for the purposes of this challenge.

** Scales **

The scales for this challenge are officially as follows:

• C: C, D, E, F, G, A, B, C
• C#: C#, D#, E#, F#, G#, A#, B#, C#
• Db: Db, Eb, F, Gb, Ab, Bb, C, Db
• D: D, E, F#, G, A, B, C#, D
• D#: D#, E#, F##, G#, A#, B#, C##, D#
• Eb:Eb, F, G, Ab, Bb, C, D, Eb
• E: E, F#, G#, A, B, C#, D#, E
• F: F, G, A, Bb, C, D, E, F
• F#: F#, G#, A#, B, C#, D#, E#, F#
• Gb: Gb, Ab, Bb, Cb, Db, Eb, F, Gb
• G: G, A, B, C, D, E, F#, G
• G#: G#, A#, B#, C#, D#, E#, F##, G#
• Ab: Ab, Bb, C, Db, Eb, F, G, Ab
• A: A, B, C#, D, E, F#, G#, A
• A#: A#, B#, C##, D#, E#, F##, G##, A#
• Bb: Bb, C, D, Eb, F, G, A, Bb
• B: B, C#, D#, E, F#, G#, A#, B

For simplicity, we can assume that both notes in the pairs A#/Bb, C#/Db, D#/Eb, F#/Gb, G#/Ab, C##/D, F##/G, G##/A are enharmonically equivalent (i.e. interchangeable - although they're not, always).

For scales with double-sharps, I will accept the enharmonic equivalents as an alternative implementation:

• D#: D#, E#, G, G#, A#, B#, D, D#
• G#: G#, A#, B#, C#, D#, E#, G, G#
• A#: A#, B#, D, D#, E#, G, A, A#

but for all other notes in the scale, they must match. If the note isn't in the scale, either can be used.

e.g.

• F in the key of C should transpose to F# in the key of C#, and not to Gb, because that option in the pair is explicitly in the scale
• but D in the key of C# could transpose to either C# or Db in the key of C, because it's an incidental anyway and so there's no easy rule to determine which it should be.

BONUS feel-good points *: normally it's # if you're going up, and a b if you're going down - feel free to implement this if you want!

For double-sharps (e.g F##) in all cases, It's OK if the program "resolves" these (e.g.to G in that case) even if they are in the scale; but again, some BONUS feel-good points * if you keep the double-sharps in.

Examples

• CDEFGABC in C to A -> ABC#DEF#G#A
• C# in C to A -> A# OR Bb
• ABCDEFGBAF#Bb in Bb to Gb -> FGAbBbCDbEbGFDGb
• CCGGAAAAGFFEEDDCGGGFFEEEDCGGGFFFFEEED in C to G# -> G#G#D#D#E#E#E#E#D#C#C#B#B#A#A#G#D#D#D#C#C#B#B#B#A#G#D#D#D#C#C#C#C#B#B#B#A#

Websites like http://www.logue.net/xp/ can be used to test your answers to other inputs

* Bonus feel-good points don't get you anything extra, unless someone can come up with a quantifiable difference that it should make to the score?

Answer 17

Interpret Unneccesary (Not quite)

Unneccesary is a joke language created by Keymaker. The source is unneccesary, and if given, it will error out.

Your task here is similar. If there is input, your program should error out. If the input is empty, your program should do nothing and terminate.

Answer 18

Mirror, Mirror, on the wall. Who's the fairest of them all?

Well, you know it's Snow White, and the evil Queen is at it again. Will Snow White be saved? Will she fall asleep once again? Will the Prince find her?

Challenge:

Given an arbitrary number (>= 2) of possibly duplicated hexadecimal color values (ranging from #000000 to #FFFFFF) and paired strings, calculate the following:

• If #FF0800 (Candy apple red) appears in the input, return "Return to Sleeping Death"
• If #000000 appears in the input, return "Saved by Grumpy"
• If #A98AC7 or #111111 appears in the input, return "Saved by Happy"
• If #21E88E or #222222 appears in the input, return "Saved by Sleepy"
• If #32DCD5 or #333333 appears in the input, return "Saved by Bashful"
• If #43D11C or #444444 appears in the input, return "Saved by Sneezy"
• If #54C563 or #555555 appears in the input, return "Saved by Dopey"
• If #65B9AA or #666666 appears in the input, return "Saved by Doc"
• If #76ADF1 or #777777 appears in the input, return "Saved by the Seven Dwarfs"
• If #FFFAFA (Snow) appears in the input, return "Saved by Love's first kiss"
• If an F variant appears in the input, return "Press F to pay respects to Snow White"
  • An F variant is any number that contains at least one F in its hexadecimal form, and is otherwise all 0s (e.g. #0FF0F0, #FFFFFF, #00000F, #F00F00)
• If multiple of the preceding occur, return the "fairest" answer. The "fairest" answer is calculated as follows:
  • For all N occurrences of special color values, choose the (N-1)/2-th (truncating division) occurrence. The associated special output is the "fairest" answer.

"Appears in the input" here refers to only the hexadecimal color values, and not to the paired strings.

• If none of the preceding occur, return the "fairest" answer. The "fairest" answer is calculated as follows:
  • Take the hexadecimal color value at the end of input values, write it down, and exclude that single color-string pair from consideration as the "fairest" answer
  • Show its binary form to the mirror, computing a reflection of only the last 24 (#FFFFFF is the mask) bits.
  • Choose the hexadecimal color with least Hamming distance from the reflection. If there are multiple (N) such colors, choose the middle ((N-1)/2-th, truncating division) instance of the color. The "fairest" answer is the associated string for the color.

Inputs:

A sequence of hexadecimal color values and String values separated by a space. The input may also be read as two separate sequences of hexadecimal color values and String values, or a single sequence of 2-tuples (either (hexValue, stringValue) or (stringValue, hexValue) is permissible, as long as the ordering is consistent across all 2-tuples). Input order matters - for each index, the corresponding element in the supply of color values is "associated" with the corresponding element in the supply of String values, and duplicates can affect the "fairest" answer. The effect is something like Function(List(HexColorValue),List(AssociatedStrings)) -> "fairest" answer. Hexadecimal color values may be represented as either (your choice of) a String "#"+6 digits, or 6 digits alone, as long as the representation is consistent across all color values.

Here's an example input:

76ADF1 Return to Sleeping Death
2FE84E Return whence ye came!

Here's another example input:

2FE84E Return to Sender
4FFAFC Return of the Obra Dinn
2FE84E Return to the house immediately, young lady!
2FE84E Return to Sleeping Death
2FE84E Return of the Jedi

Here's the third example input:

2FE84E Return to Sender
4FFAFC Return of the Obra Dinn
2FE84E Return to the house immediately, young lady!
2FE84E Return to Sleeping Death
7217F8 Return of the King

Here's the final sample input:

F4A52F Eating hearts and livers
F4A52F Eating apples
F4A52F Eating porridge
F4A52F Eating candy houses
F4A52F A Modest Proposal

Outputs:

The "fairest" answer as computed by the specified logic. For example, on the first sample input, the "fairest" answer would be Saved by the Seven Dwarfs, due to the special hex color 76ADF1 appearing within the input.

In the second sample, there are no special inputs. First, we take "2FE84E Return of the Jedi", which has value #2FE84E. In binary, this is:

001011111110100001001110

We take the reflection from the mirror, getting:

011100100001011111110100

We compare it against 2FE84E (001011111110100001001110) and 4FFAFC (010011111111101011111100), which have Hamming distances of 18 and 12 from the reflection, respectively. Since #4FFAFC has the uniquely lowest Hamming distance from the reflection, the "fairest" answer is Return of the Obra Dinn.

In the third sample input, there are no special inputs. First, we take "7217F8 Return of the King", which has value #7217F8. In binary, this is:

011100100001011111111000

We take the reflection from the mirror, getting:

000111111110100001001110

We compare it against 2FE84E (001011111110100001001110) and 4FFAFC (010011111111101011111100), which have Hamming distances of 2 and 8 from the reflection, respectively. All 3 instances of hexadecimal color value #2FE84E have minimum Hamming distance from the reflection, so we take the (3-1)/2=1th instance (0-indexed) of #2FE84E. Therefore, the "fairest" answer is Return to the house immediately, young lady!.

In the last sample input, there are no special inputs. First, we take "F4A52F A Modest Proposal", which has value #F4A52F. In binary, this is:

1111010011001100101111

We take the reflection from the mirror, getting:

1111010011001100101111

We compare it against F4A52F (1111010011001100101111), which has Hamming distance 0 from the reflection. All instances of hexadecimal color value #F4A52F have minimum Hamming distance from the reflection. There are FOUR instances of #F4A52F, because we always exclude the last hexadecimal color instance from evaluation. Therefore, we take the (4-1)/2=1th instance (0-indexed) of #F4A52F, and the "fairest" answer is Eating apples. If you don't exclude the last value from consideration, you actually get the (5-1)/2=2th instance of #F4A52F (Eating porridge), which is wrong.

Rules:

• No standard loopholes
• Input/output taken via standard input/output methods.
• The output must be exactly equal to the "fairest" answer

Scoring:

This is code golf, so shortest program wins.

_{Posted~ you can see it here}

Answer 19

CMC: Cross-Multiplication Calculator code-golf math arithmetic

In this task you should create a Cross-Multiplication Calculator.

---

Cross-multiplication is a way of factoring an algebraic expression. This is the expression form that this way can solve:

$$x^2 + ax + b$$

\$a\$ and \$b\$ are constants here, and \$x\$ is a variable.

^{Anyway, as far as I can tell, this expression form is only solvable in this method.}

Anyway, how do I do Cross-Multiplication? (TODO)

You first take the number \$b\$ and factor this number into integral factors.

Okay. We are using the expression \$x^2 + 8x + 16\$ as an example.

(Although 16 is not a prime) let us assume that 16 only has 2 possible factors:

• \$-1 \times -16\$ (because \$-x \times -x = x^2\$)
• \$1 \times 16\$ (Obviously this is 16)
• And the above 2 with the factors reversed.

Now you sum these possible two factors and check this against the number \$a\$.

• Check 1. So \$-1 + (-16) = -17\$. And unfortunately -17 is not 8, we proceed to the next check.
• Check 2. So \$1 + 16 = 17\$. And unfortunately 17 is not 8, we proceed to the next check. There are no checks left.

Did I make a mistake? Of course, I need to change the factors.

• \$-2 \times -8\$ (because \$-x \times -x = x^2\$)
• \$2 \times 8\$ (Obviously this is 16)
• And the above 2 with the factors reversed.

We sum those values, and they are -10 and 10 respectively. So I should change the factors to another value:

• \$-4 \times -4\$ (because \$-x \times -x = x\$)
• \$4 \times 4\$ (Obviously this is 16)
• And the above 2 with the factors reversed.

Finally! \$4+4 = 8\$, and here is the factorization:

$$(x+4)(x+4)$$

^{Now you will probably realize why I desperately need a program to automate this.}

Test cases

You can assume that the input is always valid. You do not have to specify the variables, only the numbers. Therefore the expression

$$x^2 + ax + b$$

is converted into:

$$+a \, +b$$

The expected output is not:

$$(x+\alpha)(x+\beta)$$

but:

$$+\alpha \, +\beta$$

a, b => α, β
8, 16 => 4, 4
-5, -24 => 3, -8

Scoring

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

Meta

• Is this clear enough?
• I haven't found a duplicate, but anything? (Although unlikely, I found nothing by searching "Cross Multiplication".)
• Tags are code-golf, string and interpreter. Anything else?
• Any further feedback?

Answer 20

Parse a regex

Grep is a wonderful tool. It can find stuff in files, it can help you spell stuff correctly (grep 'whatever' /usr/share/dict/words or wherever that file is), and it can even test if something is a prime number!

However, the first version was implemented back in the golden age, when FORTRAN was respected, Pascal was the language for beginners, and object orientation was just starting out in on its great adventure.

One could argue that modern developers have nowhere near that much talent or skill, what with their flashy "IDEs" and "frameworks". If they would be asked to implement something similar, they would just jump at the nearest library or cloud thingimabob and say "Done!".

At least, that is what some would say.

Prove them wrong! Golf grep!

Parse a regular expression without calling any built-in functions or operators explicitly meant for this.

input:

Basically the same as a simple grep: a regular expression as a command line parameter, followed by an optional filename or a dash. If the filename is not present, or it is a dash, read for stdin.

This is the recommended way to do it, but if you can write an adapter (eg: post stuff to a php form for your program via a shell script), then that is OK as well. The adapter does not contribute to your score.

output

Lines that match the regular expression.

Notes:

The regex dialect is PCRE (perl compatible). Files use unix line terminators if it is relevant.

Answer 21

Predict the state of a Minecraft inventory after click events

Minecraft does inventory management over the network by sending packets describing the clicks that a player does. If you're caching these events, it can be non-trivial to predict what state the inventory is in after the clicks

Challenge

Take an inventory of 9 slots, each with an item and a type. Assume all items can stack up to 64 and that if a slot would be "overfilled" that the cursor will continue holding onto the items. Then, take a list of the slot index, button, and mode variables for the clicks to be done (mode and button are defined at https://wiki.vg/Protocol#Click_Window). Output the inventory afterwards.

Restrictions/Rules

You may input and output the inventory in any reasonable format. You may take click input in any reasonable format. You may ignore Mode==2, as the player inventory is not implemented correctly enough for this. You may ignore Mode==3 because this is a survival player You may ignore Mode==5 where Button==8, 9, or 10 for the same reason as Mode 3. Dropping the item is a delete. Your player won't pick it back up or anything silly like that. You may assume that input will have valid counts Don't use standard loopholes

Examples

Input:

[["diamond",64],[],[],[],[],[],[],[],[]]

[
 [0, 0, 0]
 [0, 0, 1]
]

Output

[[],["diamond",64],[],[],[],[],[],[],[]]

Input:

[["diamond",64],["dirt", 64],[],[],[],[],[],[],[]]

[
 [0, 0, 0]
 [0, 0, 1]
 [0, 0, 2]
]

Output

[[],["diamond",64],["dirt",64],[],[],[],[],[],[]]

Input:

[["diamond",64],[],[],[],[],[],[],[],[]]

[
 [0, 0, 0],
 [-999, 4, 4],
 [0, 4, 5],
 [1, 4, 5],
 [2, 4, 5],
 [3, 4, 5],
 [4, 4, 5],
 [5, 4, 5],
 [6, 4, 5],
 [7, 4, 5],
 [8, 4, 5],
 [-999, 4, 6],
 [8, 0, 0]
]

Output

[["diamond",56],["diamond",1],["diamond",1],["diamond",1],["diamond",1],["diamond",1],["diamond",1],["diamond",1],["diamond",1]]

Meta

I have no clue what I'm doing writing a question.

Tagged code golf

Critique goals:

• Improve testcases
• Improve description of problem
• Determine if the problem is too complex

Answer 22

A very-very old (maybe early 2000s) problem:

Print out a decimal number \$n\$ such as \$n^2\$ ends with \$n\$ with maximal length your program can compute in 60 seconds

In other words it's needed to find some long enough \$n\$ such as \$10^{\lfloor\log_{10}n\rfloor+1}|(n^2-n)\$.
A hint may be that an \$n\$ ending with \$5\$ is more easy to compute than an \$n\$ ending with \$6\$.

code-challenge

Answer 23

JavaScript: Free for All

king-of-the-hilljavascript

This is a very experimental idea of mine: given a function which is provided a single function as an argument, try to run that function the most times possible in a browser environment while competing against other bots.

Bot submissions

Each bot consists of a function. This function takes a scoring function as input. Each bot has a state consisting of three values:

• score: Number indicating score, winning criterion
• locked: Boolean which, when true, prevents further score increases
• calls: Number of times scoring function called in last 100ms (?), will set locked to true for the remainder of the round if it exceeds a certain value

The scoring function increments score and calls, as long as locked is not true.

Restrictions

If any of these restrictions are violated, a bot will have locked set to true.

No bot or bot-defined function may:

• Run longer than 5ms
• Attempt to modify the window location (location.href, location.assign, etc.)
• Attempt to connect to the internet (AJAX, WebSockets, etc.)
• Create web workers
• Affect hardware (sound, microphone, camera, USB, gamepads, etc.)
• Download files
• Leave an impact which cannot be fixed by reloading the page

Notes

This is almost certainly a very bad idea on an assortment of levels. If you have any suggestions of restrictions or ways to make the challenge more interesting, be sure to comment.

I'm considering some sort of system to determine which bot runs first that adds to the strategy, and interesting attack angles for other bots.

To prevent this from becoming a "read the last answer and exactly cancel out its strategy" type thing, I'm open to any suggestions.

Answer 24

Given a digit as an English word, output its numerical value.

For example, given the input one, you should output 1 (optionally with a trailing newline).

Your program should cover all the following cases:

zero  => 0
one   => 1
two   => 2
three => 3
four  => 4
five  => 5
six   => 6
seven => 7
eight => 8
nine  => 9

code-golf

Answer 25

Introduction

This challenge was inspired by the 24 Game.

In the 24 Game, you are given 4 numbers and are asked to make 24 using addition, subtraction, multiplication, division, and parentheses. So...

What is the biggest number you can make given 4 numbers using the above operations?

Challenge

For four given inputs a, b, c, d, output the biggest number you can get using addition, subtraction, multiplication, division, and parentheses.

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

Example Input and Output

  Input  -->  Output  -->   Explanation
 1,3,2,4 -->    36    --> (1 + 2) × 3 × 4
 5,5,5,5 -->   625    -->  5 × 5 × 5 × 5
 9,2,3,1 -->    81    --> (1 + 2) × 3 × 9
 

---

Please give feedback on this challenge and correct me if my outputs are wrong. Should I change it to the smallest number?

Answer 26

How many ACus do I have?

Posted to main

Answer 27

Make a Decompiler Bomb

Similar to the Make a Compiler Bomb challenge, but backwards.

The goal is to create the a 1KiB (1024 bytes) or smaller bytecode file that creates the largest output when decompiled.

Constraints

• A binary is either an x86 binary (in the form of an ELF file, PE file (.dll/.exe), or Mach-O binary) or a virtual bytecode file (e.g. Python .pyc, Java .class, .NET CLR, etc.)

• The decompiler can be any public (preferably free) decompiler of your choice. (e.g Snowman/Hex-Rays for x86 binarys, CFR/Fernflower/etc. for java, dotPeek for .NET, uncompyle6 for Python, etc.)

• A decompiler is any tool that takes a binary and attempts to reconstruct human readable source code from it.

• The largest output byte count wins, with the smallest input size as a tie-breaker

• The binary must be executable, and print "Hello World!"

• The decompiled code must be syntactically correct

Answer 28

I delete the input, you delete the source code

file-systemcode-golfstring

This is a new twist on the long running series on CGCC.

Your task, if you accept it, is to write a program/function that outputs/returns the contents of an input file. The tricky part is that if I delete the input file, your program must delete itself.

Rules

• The source code file and the input file should be in the same directory.

• The input file and source file can be named anything at all. I.e. The file names are your choice.

• The contents of the input file will be restricted to printable ASCII.

• The input file and the source file must be deletable.

• This is code-golf, so the shortest (original) code in each language wins!

• Default Loopholes apply.

Example

If your program is jspwjxnlow8229 and the input file exists, the program must print the contents of the file. If the file doesn't exist, the program must delete itself.

Feedback

In regards to file manipulation, have I specified the rules enough?

Answer 29

How healthy are my children?

As anyone who has twins will know, it can be hard to keep track of which child fed / was changed, and when.

That's why I've devised a system using OneNote on my phone. It's quick and easy to use.

Each entry (line) uses the following structure (note: I'm not a regex expert and the expression is more permissive than I want - see words for detail):

(ddMMyyyy )?HHmm ((1|2|B) (💧|💩|🤱){1,3}){1,3}

Or, in words:

1. For the first entry on or after midnight each day only, each line starts with the date.
2. The next component is always the time, hour and minute in 24 hour clock format
3. Next is a child identifier character - 1 or 2; or B if what follows applies to both children. All subsequent emoticons apply to the identified child, until a new child identifier is found or a newline. There is guaranteed to be at least one child identifier in a record.
4. Next comes any or all of the three emoticons (maximum one of each) representing a wet nappy (💧), a dirty nappy (💩) or a feed (🤱)
5. Repeat from step 3. until done. BUT - each emoticon will only appear once per child - so if it appears in B then it won't appear in either 1 or 2; and if it appears in either 1 or 2 it won't appear in B. It won't appear in both 1 and 2 (because then it would be in B instead). The regex doesn't show this subtlety.

Some other notes:

• Breast-Feeding (feed) emoticon 🤱 is codepoint U+1F931
• Droplet (wet) emoticon 💧 is codepoint U+1F4A7
• Pile of Poo (dirty) emoticon 💩 is codepoint U+1F4A9
• All items in the string are space-separated
• I would actually use the initials of my children's names, rather than 1 and 2 - but for the challenge I went with the numbers instead.

Example

02022020 0005 1 💩 B 💧 🤱
0230 2 💧 🤱
0250 1 💧 💩 🤱
0330 2 🤱
0400 1 🤱
0700 B 💧 🤱
0900 2 🤱
1000 2 💧 🤱
1020 1 💧 🤱
1220 1 🤱
1420 B 💧 1 💩 2 🤱
1440 1 🤱
1600 2 💧 💩
1700 1 💧
1745 B 🤱
2100 B 💧 🤱 1 💩
2350 2 🤱 B 💩 1 💧
03022020 0015 1 🤱 B 💧
0500 1 💧 🤱
0830 1 💧 🤱
0900 2 💧 🤱
1115 B 💧 1 💩
1215 B 🤱
1330 B 🤱
1400 2 💧 💩

The Challenge

Given the raw data, input as a single string or array of entries, containing data such as the above example, output a summary of:

• number of feeds, wet and dirty nappies, per baby, over the past 24 hours

"The past 24 hours" can be either based on system time, or the current time can be passed as an extra input.

The output format is up to you, as long as it:

a) is consistent across all runs of the program
b) shows the information required

some example outputs for the above inputs, with a current time of 14:30 on 3rd of February 2020 (hand-calculated, sorry if they're not right!):

Baby 1 had 6 wet nappies, 2 dirty nappies, and fed 8 times Baby 2 had 6 wet nappies, 3 dirty nappies and fed 6 times

{{6,6},{2,3},{8,6}}

{6,2,8},{6,3,6}

etc.

This is code-golf so lowest bytes wins. Usual exclusions apply.

Answer 30

I want to ask a combined popularity / objectively scored question. Something like:

Take a string as input. Match the string to a famous painting such as "Mona Lisa" and render a cartoon version of it. 1 point per painting, 1 point per upvote. Voting closes on XX/YY/ZZZZ.

I want to reward people for including more possibilities (there will be a fixed upper limit, unlike with paintings). I also want to reward people for the quality of their renderings. The cartoon paintings should be recognisable as versions of the real paintings.

Is this a good scoring system? If not, what would be better?