Sandbox for Proposed Challenges

Question

What is the Sandbox?

This "Sandbox" is a place where Code Golf users can get feedback on prospective challenges they wish to post to the main page. This is useful because writing a clear and fully specified challenge on the first try can be difficult. There is a much better chance of your challenge being well received if you post it in the Sandbox first.

To post to the Sandbox, scroll to the bottom of this page or click on the "Add Proposal" link below, 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. 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, replace the post here with a link to the challenge and delete it.

See the Sandbox FAQ for more information on how to use the Sandbox.

The Sandbox works best if you sort posts by "active".

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• Most people include applicable tags in their proposal, so for instance you can search for all king-of-the-hill proposals by merely adding the tag name in quotes to the search query.

Browse your pending proposals

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To add an inline tag to a proposal use shortcut link syntax with a prefix: [tag:king-of-the-hill]

Answer 1

create a golfed down regexp that matches all substrings

inspired by Determine the "Luck" of a string where I found a way to golf almost 30 bytes at once
(with a falling trick for that challenge, but I still like the idea).

The word "lucky" contains 15 different substrings:

• lucky
• luck, ucky
• luc, uck, cky
• lu, uc, ck, ky
• l, u, c, k, y

Challenge
Create a program or function that, for a given string s, creates the shortest possible regexp using basic PCRE syntax that matches and returns all substrings of s and nothing else.

• code needs not to be case sensible
• basic syntax means: alternatives, quantifiers, grouping and custom character classes (e.g. [abc])
• other features (assertions, backreferences, recursion etc.) may be used, but are not required to qualify
• the result may include delimiters and modifiers

The result for lucky would be l?ucky?|l?uc?|c?ky?|l|c|y.

---

• is the description sufficient?
• the challenge not too easy, not too hard?
• any other hints you might have?
• I will add test cases that expose possible bugs (like silly and digdug)
• not sure yet if I will go for shortest code yet

Answer 2

Write a Gopher Interpreter

This code golf challenge will task you with writing an interpreter for an esolang I created a while back called Gopher, Details on the language can be found Here

Pass Conditions

This challenge requires you to create an Interpreter (Or you could go a step ahead and create a Compile/Transpiler) however for the code to pass as correct it must meet the following criteria

• Take in a single input being the Gopher Code

• Output the result of the Interpreted code

• Invalid code does not need to be handled, however you may do so if you wish

• As this is code-golf the smallest byte size wins

Example Input and Output

Input:

&++<'×<&÷+<^-<<×-<#!+<$@-<&@<×-<@++<@<.!<=

Output:

Hello World

Answer 3

Having had a look, it seems there isn't a challenge for "Given any date, output the day of the week". Is that a challenge worth having?

Something like

"Given an input date, in the form dd/mm/yyyy, output the day of the week"

Shortest code wins

What do we think? perhaps this already exists and I didn't find it.

Answer 4

Golf your way from (inc|dec)rements to the basic math operations

Write five different functions or programs that do addition, subtraction, multiplication, division and modulo with integers by only using increments, decrements, loops/recursion and comparisons.

• Assume division & modulo will never receive 0 or negative integers as the divisor/modulus.
• Modulo's result has the sign of its dividend.
• Division truncates its quotient, e.g divide(11, 4) returns 2 and divide(-5, 3) returns -1.
• Programs must print the result to STDOUT. Functions must return the result.
• Your five functions/programs may invoke each other.
• All functions/programs must support 32-bit signed integers, i.e everything between -2³¹ and 2³¹-1 (inclusive). Overflow is allowed, i.e it's OK if add(2147483647, 1) returns -2147483648.
• Explicitly adding/subtracting 1 to/from numbers is allowed, in case you use a programming language that doesn't have built-ins for incrementing and decrementing.
• Shortest program wins as long as it doesn't exploit standard loopholes!

code-golfrestricted-sourcemath

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I seriously have no idea how to make test cases for this.

Answer 5

ASCII to Unicode equation beautifier

You may well be used to typing equations in ASCII, but with the advent of Unicode we can spruce them up a bit. We can fix

• Powers (numeric superscripts only)
• Numeric subscripts
• Mathematical signs (-, *, / ^ → -, ×, ÷, ↑)

Examples:

x^3 - 1 = (x - 1)(x^2 + x + 1)  →  x³ − 1 = (x − 1)(x² + x + 1)
g_0 = 3^^3^^3 -= 3^(3^3)        →  g₀ = 3↑↑3↑↑3 = 3↑(3³)
800*600                         →  800×600
1/x                             →  1÷x

You may assume that all digits directly after a ^ or _ are meant to be super/subscripts (and the ^ or _ to be removed) and that all the mathematical signs are to be replaced wherever they appear.

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

Answer 6

Autotune a chord

Auto-Tune is a pitch correction program which alters the pitch without changing the length. It can be used to fix off-pitch chords in music, which is good because I have an out of tune piano. The goal of this challenge is given some input waveform which contains a single chord played on my piano, tune each note to the nearest equally tempered note found on a standard piano (see Input for more details).

Input

The input is something which looks like a time-domain audio sample input containing a single chord being played. All data is sampled at 192kHz, with 16-bit PCM (little endian integer), mono channel. The input may come from any source desired (file io, stdio, function parameter, etc.).

Output

The output of your code should be something which looks like a time-domain audio sample containing the tuned chord. It does not need to have the same sample rate or datapoint format as the input, but must be the same length in real time as the original sample (or as close as possible). The output may be to any source desired (file io, stdio, function parameter, etc.).

Examples

See this github repo for various inputs and outputs. The provided examples have inputs/outputs in an uncompressed wav file. Feel free to re-encode/gut the data for your inputs.

Scoring

This is code golf; shortest code wins. Standard loopholes apply. You may use any libraries/builtins so long as they were not designed specifically for performing pitch correction.

Main concern: This challenge seems potentially too difficult, so one alternative I've been considering is changing the piano samples into sine waves at the fundamental frequencies (avoids issues with amplitude decay/harmonics). An even simpler challenge might be to give inputs in the frequency domain (list of fundamental frequencies), though I'm not sure that would make for an interesting challenge as it seems almost too easy at that point.

code-golf music

Answer 7

This will be a code-golf challenge. Additional tags are internet, date and math.

How fast is your Stack Exchange community?

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tl;dr

Your task is to find how fast a Stack Exchange community reacts. "How fast" is here the average of the time elapsed until the first answer or the closing of the question.

Input

• the Stack Exchange site's name, e.g. stackoverflow, codegolf, codereview etc.
• optionally the Stack Exchange API URL: https://api.stackexchange.com/2.2/

Requirements

• Calculate the average time it takes until the first answer or closing of the question.
• Take the 1000 latest questions into account, e.q. ten API requests with 100 items each.

Output

• Output the average time in minutes and seconds, like 01:23 or 1:23.
• Run your program at least against stackoverflow, codegolf and code review and show the results.
• Feel free to add results for your other favorite communities as well.

Boilerplate

• You can write a program or a function. If it is an anonymous function, please include an example of how to invoke it.
• This is code-golf so shortest answer in bytes wins.
• Standard loopholes are disallowed.
• Leading/trailing whitespaces/newlines are fine.

Answer 8

Convert a BMP image to grayscale

The images manipulation is a great way to exercise and increase your skills. In my opinion it's also very interesting.

What you must do?

The objective of exercise is much easy: convert an image bmp colorful in an image grey.
You can use every language, the question most appreciated will be that don't use library.
Image stock: http://www.mediafire.com/convkey/c491/p7aya9cxafvfc91zg.jpg Image converted: http://www.mediafire.com/convkey/3903/rcigd79pkwd12qczg.jpg?size_id=3

Answer 9

Do I have an emoji?

code-golf string

Given an input string in your language, return truthy/falsey if the input contains an valid Unicode emoji character.

What is an Emoji?

The word emoji comes from the Japanese:

絵 (e ≅ picture) 文 (mo ≅ writing) 字 (ji ≅ character).

Emojis are pictorial symbols used to represent feelings, actions, or objects.

For this challenge, use the Full Emoji Data list provided by Unicode as a reference to determine which characters are valid Emojis.

Sample test cases:

"" -> 0

"💩" -> 1

"hello💩" -> 1

"hello" -> 0

"!±≡𩸽" -> 0

---

Discussion:

This seems trivial, but I noticed we didn't have an emoji detection challenge. There might be a concern about the encoding of the input string, but reading the linked meta posts about Strings I feel that this challenge can use whatever String format the language used in the answer supports.

The acceptable output for booleans is also up for discussion. Do we have a meta post on what output formats are acceptable for booleans?

Answer 10

Trim trailing spaces in less than O(n²) time

Since s/\s+$// runs in O(n²) time, Stack Overflow needs to replace it with something faster. Please write a code snippet for them. Your score will be the number of bytes in your submission, multiplied by the time taken to process a string of 1000 non-spaces with 1,000,000 leading and trailing spaces, divided by 1000 times the time taken to process a string of 1-non space with 1,000 leading and trailing spaces. (In other words, if your code runs in O(n) time then this should cancel out.)

Answer 11

Reverse stdin to stdout, Unicode aware and by grapheme clusters

It's 2016. High time that we were Unicode-aware, don't you think?

Given a UTF-8 string on stdin, reverse it by extended grapheme clusters (as defined by the Unicode consortium; this can be found here, for instance) and place it on stdout. This is seemingly a trivial challenge, but surprisingly difficult in many languages.

You may not use an explicit end-of-file character - if supported, use EOF. If not supported, use an explicit length at the start of the string, and document the format.

Note that the string may be of any length (barring RAM limitations).

You must handle direction override characters "properly", in the sense that the directionality of every character must remain the same after reversing the string.

Answer 12

Given an ordinal A and a nonnegative integer B, compute f_A(B)

A will be expressed in Cantor Normal Form. A number is in Cantor Normal Form if it is 1, or if it is either of the form a+b or w^a, where a and b are in Cantor Normal Form, and w is the ordinal omega.

f_A(B) is the fast-growing hierarchy, specifically, the Wainer Hierarchy. f_0(n)=n+1. f_(a+1)(n)= n iterations of f_a to n. f_a(n)=f_an if a is a limit ordinal. a[n] is the nth member of the fundamental sequence for a.

Answer 13

code-golf number

Difficulty Naming

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Introduction

In the game osu!, players can make their own beatmaps (levels). The harder the beatmap is, the bigger the star rating will be.

Beatmaps have star icons with different colors and letters according to their star rating.

osu! has also four game modes. The shape of the icon will change depending on the game mode.

The Challenge

Given a star rating and a gamemode, output the (generally used) difficulty name.

The Input

• A positive floating-point number (star rating)
  • You can assume the number will never have more than two decimal places.
• A positive integer (game mode)
  • 1 is Standard, 2 is Taiko, 3 is Catch the Beat and 4 is Mania (you can use other numbers for the game modes, these are the default.)

The Output

• A string (difficulty name)

Use this table to determine the output:

diff table http://image.prntscr.com/image/174e34e56dbb40ad81b209fac3fdc5bc.png

(if the star rating is exactly 5.25, it counts as Above 5.25)

Rules

• This is code-golf, so the shortest solution wins.
• Standard loopholes are disallowed.
• You can take the input either as an array/list, a string separated by commas or spaces, or each number individually.
• Again, you can use other numbers for the game modes.

Test Cases

2.24, 2 ---> Futsuu
1.1, 4 ---> Basic
3.14, 1 ---> Hard
7.0, 3 ---> Overdose
5.0, 4 ---> Exhaust
31415.0, 2 ---> Ura Oni
0.01, 1 ---> Easy
5.25, 1 ---> Expert

---

Sandbox

If you see any grammar errors or anything like that, please tell me, I'm not a native speaker.

Answer 14

Could it all add up to nothing?

Given an input number, return a truthy value if it is possible to arrange permutations of + and - signs to make the sum of the range up to that value 0.

Note that you don't have to output which set of combinations is truthy.

Test cases:

1 (1) --> Falsy
2 (1,2) --> Falsy
3 (1,2,3) --> 1+2-3, Truthy
4 (1,2,3,4) --> -1+2+3-4, Truthy
5 (1,...,5) --> Falsy
6 (1,...,6) --> Falsy
7 (1,...,7) --> 1+2-3-4+5+6-7, Truthy
8 (1,...,8) --> 1+2-3-4-5-6+7+8, Truthy

Just one thing - no using eval or similar commands.

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

Sandbox notes

Require a range or a list as input?

Answer 15

Grow and Visualize Decision Tree

META: work in progress...

• Would providing the points as an image instead of a list of coordinates simplify the challenge?

code-golfgraphical-outputgraph-theorymachine-learning

Given two sets of points in the plane with coordinates x,y, both in [0,1), grow a (binary) decision tree as specified below and output a square pixel image of a given size, that visualizes the corresponding tree.

How to grow the tree

The we call the two sets here classes and follow the following recursive approach:

1. If at least one of the classes is empty, label the current node as a leaf of the nonempty class and stop. Otherwise:

2. First find the mean of each of the x (or y)-coordinates of each of the two classes, and find the mean/center c of those two means. Then we partition both classes as follows: All points with an x (or y)-coordinate strictly smaller than c belong to one half, all the other ones to the other half. The we set the current node to the decision is the x-cooridinate (or y-coordinate) less than c?

3. For each of the halves, go back to step 1 and 2, and set the resulting nodes as the child nodes from the current node. If you previously considered the x-coordinates, then consider y-coordinates and vice versa.

How to visualize the tree

We partition the the unit interval [0,1) into N equidistant sub intervals [0,1/N), [1/N,2/N), [2/N,3/N)... and correspondingly the unit square [0,1)x[0,1) into squares

[i/N,(i+1)/N)x[j/N,(j+1)/N) for i,j=0,1,2,...,N-1

which later will be represented by a pixel. For each square [i/N,(i+1)/N)x[j/N,(j+1)/N) we classify the point i/N,j/N with the tree we just grew and colour the corresponding pixel with the corresponding colour.

For the example above the output would look like so:

Details

• Input: An integerN>5 and two sets of points in any convenient format (e.g. as two separate list of points, or as a single list with a label for each point etc.) You can assume that in total there is at least one point.
• Output: A pixel image (vector images composed of squares are ok too) of the visualization.
  • You have to choose any two distinct colours, I recommend blue and red.
  • The x-axis should point to the right, the y-axis can point in any direction.
  • The submission should display the image on the screen or save it to a file (like jpg/png/tiff or similar formats)

Answer 16

Make a sequence from a sequence!

(Title is bad and I should feel bad)

Given a sequence of positive Integers, take each consecutive pair of two (without taking an element two times) (x,y) and print y x times.

For example for 3,1,4,2

1. Pairs are (3,1) and (4,2)
2. (3,1): Print 1 three times: 1 1 1
3. (4,2): Print 2 four times: 2 2 2 2
4. Resulting sequence/output is 1, 1, 1, 2, 2, 2, 2

Input

A sequence of positive integers divisible by two. This can be done by parameters, a flat array, an integer stream etc. AS LONG AS there's no nesting or pre-matching of pairs involved.

Output

The resulting sequence as showcased above. Same rules for datatypes as declared in input, keep everything flat.

Test cases

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

Reference Implementation (Ruby, 55 bytes)

f=->a{a.each_slice(2).collect{|x|Array.new *x}.flatten}

Ungolfed:

def g *a
  a.each_slice(2).collect do |x|
    Array.new(x[0], x[1]) 
  end.flatten
end

The first golfer to find a shorter solution in this language gets a -1 bonus.

Scoring

Shortest code in bytes wins.

Answer 17

CAPTCHAs (Cops and Robbers Style)

cops-and-robbers

Cops will write a program that generates a CAPTCHA (either through stdin/stdout or on whatever UI is available to your language using only built-ins).

Robbers will attempt to bypass the generated CAPTCHA programmatically, given access to the Cops' programs' stdin/stdout or UI process/thread (for example, in JavaScript, running on the same document and window).

I need help fleshing this idea out a little more... any suggestions will help.

Answer 18

Create me a Brainf*** assembler

Write a way to convert "human readable" assembly (of any kind) to Brainf***. I.E specify a language "X" (which may already exist or may be your own invention), and create a way to map each valid program to a valid Brainf*** program. This is a popularity-contest so the most convenient assembler as evidenced by upvotes wins!

Answer 19

King of the golf course

Write a program that golfs Brainf*** programs. Similar to code-golf challenges on this site, you will be racing against the clock, and the byte count to maximize glory (reputation). Each program will be invoked with a series of command line arguments in this form

in out in out in out

Each program then has 1000 milliseconds to write a valid brainf*** program to botName.txt. This brainf*** program will take in a null terminated input from stdin and output the respective output according to the table. The code which writes the shortest programs as evidenced by the shortest of 5 runs (or more) will be crowned the winner with a green checkmark. Please note that my languages I support is limited and I may have to download the interpeter. I will have to disqualify non-free interpreters unless volunteers already possessing the interpereter/compiler are willing to help out.

---

Rules

1. You may assume that anywhere from 15-30 in and out pairs will be provided.
2. You may assume that inputs and outputs are valid english words from Random House Dictionary
3. You may assume a non wrapping brainf*** implementation with byte values for cells and a tape size of no less than 30k cells
4. The outputted bf programs may be of any length, but your submission may be no more than 10 kilobytes long (to prevent hardcoding)
5. Invalid submissions will result in immediate disqualification until a bug patch is uploaded

meta-golfbrainfck natural-language code-challenge

Answer 20

Expand constants in a Brainfuck program

code-golf metagolf kolmogorov-complexity code-generation brainfuck

Introduction

When golfing in Brainfuck, Fred can never remember the shortest way to write any given constant, and looking it up takes too much time! Luckily, Fred remembered that PPCG can help! In this challenge, you'll need to convert base-10 numerals their Brainfuck representations.

Challenge

Write a program or function that takes a string of Brainfuck code containing some numbers, like this:

72.>105.>33.

and transforms each number into one of its Brainfuck representations, giving (for example) this:

-[>+<-------]>-.>+[->-[<]>--]>.>>-[-[-<]>>+<]>.

Because Fred has not yet learned the secrets of Ctrl+C Ctrl+V, your code must be as small as possible to save Fred some valuable typing. Fred also wants to win code-golf contests with the output, so the code you generate must also be as small as possible.

Specification

• Standard loopholes are forbidden; in particular, you cannot scrape http://esolangs.org/wiki/Brainfuck_constants (or any other site for that matter).
• Your program or function may perform I/O through any of the default I/O methods.
• Assume a wrapping implementation with 1-byte cells (i.e. -. gives ÿ (255)).
• There will never be a number greater than 255 or less than 0 in the input (but you do have to handle 0 correctly!). Your program/function must handle all numbers 0-255 (inclusive).
• You may assume that there are as many temporary cells as necessary to the right of the pointer location (but not the left).
• You may assume that the cell where a number will go and all temporary cells are set to 0.
• When substituting a number, the pointer must end at the cell with the number. All temporary cells must be reset to 0.
• You may assume that there will never be any non-Brainfuck, non-digit characters in the input, and that the input will never be empty (i.e. the input will match /^[,\.\[\]+\-<>0-9]+$/).

Test Cases

The test cases given below are the output for a program/function using the shortest "wrapping" version of the constants at http://esolangs.org/wiki/Brainfuck_constants.

Input
Output
Brainfuck program's output

72.>105.>33.
-[>+<-------]>-.>+[->-[<]>--]>.>>-[-[-<]>>+<]>.
Hi!

255>10++>65>255<+[-<+]->[-+[->+]-<.+[-<+]->]
->++++++++++++>>+[+[<]>>+<+]>>-<+[-<+]->[-+[->+]-<.+[-<+]->]
AAAAAAAAAAAA

>0>48-->255<[>>86.[-]+[-<+]-<-]
>>-[>+<-----]>----->-<[>>-[>+<---]>+.[-]+[-<+]-<-]
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV

>,[>,]<[<]>[.>]
>,[>,]<[<]>[.>]
(cat - outputs the input)

Scoring

Your score is your byte count plus the average length of your program/function's output for each number. For example, if a 30 byte program's output had an average length of 13.5, its score would be 30 + 13.5 = 43.5.

Helpful Hints

• http://esolangs.org/wiki/Brainfuck_constants

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Sandbox Questions

Is it tagged correctly? Should this be code-challenge instead of code-golf metagolf?

Answer 21

Convert hexagonal coordinates to index

Your job is to, given the size of the hexagon and a pair of axial coordinates, return the index as if all the rows were laid out side by side.

Here's an example mapping for size 3:

(q,r), 3

       (0,0) (1,0) (2,0)
    (-1,1) (0,1) (1,1) (2,1)
(-2,2) (-1,2) (0,2) (1,2) (2,2)
   (-2,3) (-1,3) (0,3) (1,3)
      (-2,4) (-1,4) (0,4)

maps to

    00 01 02
  03 04 05 06
07 08 09 10 11
 12 13 14 15
  16 17 18

Here's the formula I found (could be improved):

i=index
s=size

i = q + sum( ( 2 * s - 0.5 - abs( x - s + 0.5 ) ) for x in 1..r )

Test cases (0-based indexing):

(q, r, s) -> i

(0, 0, 1)  -> 0
(0, 0, 50) -> 0
(0, 3, 3)  -> 14
(-3, 5, 4) -> 28
(5, 2, 12) -> 18

---

Meta notes:

• Should I include links to axial coordinates and centered hexagonal numbers?
  • Or, instead, should I explain axial coordinates better?
• Should I include the formula I came up with?
• More test cases, or are those fine?
• More exposition?
• I'm also planning to do a challenge the other way around, is that ok?

Answer 22

Rules

• Your program must take no input and print this text.
• You can have trailing newlines, and spaces after lines.
• You must not use a builtin or load the text for an external resource.

Score

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

Did you guess what was the text?

Answer 23

Point Triangulation

(title suggestions welcome)

code-golf geometry

Triangulation has been used for hundreds of years for land mapping and cartography, until the widespread proliferation of satellite positioning systems. Essentially, if you know two fixed points, A and B, you can uniquely describe a third point C by describing the angles BAC and ABC (the angle-side-angle postulate). The challenge here will be to solve for C.

Input

• Two rays (half-lines) of the form [(a point in x,y coordinates), (a direction in degrees or radians)] in any convenient format.
• The input angle will be relative to the Cartesian plane, i.e., an input of 0 degrees will have the ray parallel to the x axis and pointing toward x=+inf, and will follow traditional Euclidean convention that the angle increases counter-clockwise (e.g., 90 degrees is "straight up" toward y=+inf, 180 is "straight left" toward x=-inf, etc.).
• Please specify in your description the input format you're using.

Output

• The corresponding third x,y coordinate where the rays intersect, thus forming the triangle.
• If the input will not form a triangle, you can output an error, crash, output nothing, etc., so long as your code terminates. (META - is this too harsh? Should the input be guaranteed to form a triangle?)

Examples

[(1,0,90), (0,1,0)] -> (1,1)
[(1,0,90), (0,0,45)] -> (1,1)
[(1,0,90), (0,1,180)] -> undefined

additional examples forthcoming

related

Answer 24

Smallest Vigenere cypher executable

Brief

Impliment a Vigenere cypher program in your favourite language to create the smallest compiled program in any operating system.

For people unfamilar with a Vigenere cypher program, please visit the following link: https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher

Scoring

• Your score is the size in bytes of the folder that contains the main executable.

To find this, you must first compile your program. Secondly, delete any files unecessary to the running of your program. Finally, right-click on or list details by command line the folder (or equivalent standard action depending on operating system) containing the compiled executable and note the smallest of the listed size (e.g. size or size on disc in Windows) in bytes value.

• If dlls or similar are referenced, then their size in bytes must be added to the score.

• Interpreted languages may be used, but the size of a compatible interpreter (e.g. a web browser if using javascript) must be included when calculating the score.

Specific details

The program must accept 3 arguments:

• Argument 1 must be either 'e' or 'd', with e meaning encrypt and d meaning decrypt
• Argument 2 is the keyword string.
• Argument 3 is the main input string.
• If Argument 1 is 'e' then Argument 3 is the message to be encoded.
• If Argument 1 is 'd' then Argument 3 is the message to decoded.

The program must output the result only:

• If Argument 1 is 'e' then the result is the encoded string.
• If Argument 1 is 'd' then the result is the decoded string.

Rules

• The earliest dated post with the lowest score wins.
• In your answer post, post enough information so that others may repeat steps described to arrive at the same result. Presume that people reading your answer are fluent in your chosen language, but may not necesarilly understand any nifty tricks or exploits.
• Include your score in your answer post to let everyone know your score.
• You may post all your source-code if you like, but may also post only the parts that you feel are significant. There is no need to post automatically generated code, although if it is generated by a plugin then this should discussed. Failure to do so is considered cheating.
• Edits may not be made to answers. If you have made a mistake then delete and repost your answer anew.
• All edits and mistakes are considered cheating. Cheat answers are identified by members of the community leaving a comment. Cheat answers must be deleted, corrected and reposted.
• The community must use the comments to report cheating only. Be careful reporting cheats as a mistake may result in a good answer being deleted.
• Improvements should be listed as a new answer post.
• Take the competition seriously and be a good sport. Avoid ribbing, jokes or childish remarks.
• Have fun

Answer 25

N-ary Time

Decimal time is a concept of having days, hours, minutes, and seconds relate to each other by powers of 10:

N-ary time, which I made up, is having days, hours, minutes, and seconds relate to each other by powers of N.

Given an input N where minumum(2^31-1, [languages upper limit on integers])>N>1, output the value of an N-ary hour, N-ary minute and N-ary second, in seconds, using these rules: There are N^1 (10 in base-N) N-ary hours in a day, there are N^2 (100 in base-N) N-ary minutes in an N-ary hour, and there are N^2 (100 in base-N) N-ary seconds in an N-ary minute.

There are 86400 regular seconds in a day.

Input

Input must be an integer, inputted in anyway allowed

Output

Output consists of floats or integers that represent the amount of seconds in each N-ary unit within 0.5 seconds . Order is irrelevant.

Test cases

input-->output

2-->[43200.0, 10800.0, 2700.0] (or some other way of representing the data)

8-->10800 3 169 (numbers don't have to have specific order)

3-->28800.3200.356 (note that this might have the same character as decimal points, but it's still clear that they are three separate numbers)

Answer 26

Floating Point Error

Given a basic arithmetic problem, the division, multiplication, addition, or subtraction of two numbers (which are representable in a 32bit floating point), output the percent difference between the actual (mathematical) result and the nearest floating point value. The percent difference should be rounded to a whole number.

You may use either 32bit or 64bit floating point following the IEEE Standard for Floating-Point Arithmetic (IEEE 754).

The percent difference is calculated in the following manner:

100 * (Actual - Float) / Actual

You may round to a whole number in any of three ways, as long as you only use one method: (1) floor, (2) ceiling, (3) nearest.

Examples and Test Cases, yet to come.

Answer 27

Bomb Drops

code-golf [tag:???]

The Challenge

Your task is to create a program that simulates "dropping bombs" on a 2 dimensional array.

For example consider the following 2d array:

3 0 5 0 5
5 3 4 0 2
1 0 5 4 2
2 4 2 3 2
2 3 3 0 0

Dropping a bomb on a single cell decreases the value of that cell by 2 and the value of its direct neighbors (including diagonal neighbors) by 1, to a minimum of 0.

If we were to drop on a bomb on the cell corresponding to array[2][1] where the value is 4, or coords (2,1), then the new 2d array would look like so:

3 0 4 0 5
5 2 2 0 2
1 0 4 3 2
2 4 2 3 2
2 3 3 0 0

Input

Your input will be a two dimensional array of integers greater than or equal to zero, in whatever way you like.

You will then also take input that is a sequence of tuples, lists of size 2, or whatever else you please that corresponds to coordinate points. For example,

(2,1),(3,4),(0,0) or [2,1],[3,4],[0,0] or 2,1,3,4,0,0

For each of these points, you will simulate a bomb drop on that point. You do not need to worry about these coordinates being out of range of the 2d array.

Output

Output consists of a two-dimensional array, formatted the way you please.

Test Cases

>>> [[0, 1, 3, 1, 1], [3, 5, 1, 0, 4], [1, 1, 1, 0, 2], [1, 2, 0, 3, 4], [5, 2, 0, 2, 2]]
# 0 1 3 1 1
# 3 5 1 0 4
# 1 1 1 0 2
# 1 2 0 3 4
# 5 2 0 2 2
>>> [3,4],[2,1],[0,0]
0 0 2 0 1
2 3 0 0 4
1 0 0 0 2
1 2 0 2 3
5 2 0 0 1

# You can also take input in one pass, rather than 
# having the 2d array and the coordinates be seperate inputs:
>>> [[5, 2, 3, 0, 3], [4, 3, 5, 5, 5], [1, 3, 3, 3, 3], [0, 1, 2, 3, 1], [3, 1, 2, 2, 4]],[2,2],[0,1],[3,3]
# 5 2 3 0 3
# 4 3 5 5 5
# 1 3 3 3 3
# 0 1 2 3 1
# 3 1 2 2 4
4 1 3 0 3
2 1 4 4 5
0 1 0 1 2
0 0 0 0 0
3 1 1 1 3

Other info

Inspired from this question on StackOverflow.

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This is my first challenge, I'm looking for any advice at all. I'm not sure what other tags to put aside from code golf. I'm probably missing a few basic rules etc too that I've forgotten about. All suggestions welcome.

Answer 28

Paint with all the colors of the RGB rainbow

^{Inspired by Images with all colors and American Gothic in the palette of Mona Lisa: Rearrange the pixels}

Given an input raster image, output a raster image where each pixel is a unique color, such that the sum of the absolute value of the sum of the differences of the RGB channel values for each pixel between the original image and the output image is minimized. In other words, that means, given an image O, find an image X such that every pixel is a different color, and (in pseudo-Python) the quantity sum(abs(O_pixel.RED - X_pixel.RED) + abs(O_pixel.GREEN - X_pixel.GREEN) + abs(O_pixel.BLUE - X_pixel.BLUE) for O_pixel,X_pixel in zip(O.pixels, X.pixels)) is minimized.

3-bit example

All images in this example are 4 pixels wide by 2 pixels high, magnified 40x to 160x80 so that they can be seen more easily.

Original image:

The palette:

The image using each color from the palette that is closest to the original (minimum sum 6):

Specifications

• All images will use 8-bit colors (3 bits in the red and green channels and 2 in the blue channel), and will be 16x16. Here is an image displaying the 8-bit color palette. Each color from this palette must be used exactly once in the output image.
• Submissions must complete for any of the test images in under 1 minute.
• If there are multiple optimal solutions, any one of them may be used.

Test cases

Original is on the left, expected output is on the right. All of these images are zoomed in; click the links to get the original-sized images.

Note that these two are the same, because the original image is already composed of unique pixels. Thus, the minimum sum is 0.

(more to come once my computer finishes generating them)

Answer 29

Convert Between American and British English Spellings

code-challenge test-battery natural-language

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In this challenge, you will have to write two programs or functions. One will convert a list of words from their American English spelling to the British English equivalent, and the other to convert the other way. Here's that catch: you only have 300 bytes to do both!

The Challenge

You can find a gist here that contains a list of 1000 words. The file is formatted so each line is british-spelling(space)american-spelling. Therefore, there are only 500 words in total, each with 2 spellings. This file is for your convenience, and it was based on the list found here.

Your challenge is to write two programs or functions (has to be two programs or two functions, it can't be one program and one function). Both will take a single string as input and output a single string. The first program/function will take in British English words and output the American English spelling, and the second will take in American English words and output the British English spelling. Built-in functions or libraries that do this task are not allowed, nor are standard loopholes. You also cannot hard-code the list into your program. Your programs and functions have a shared 300 byte limit, i.e. length(program1)+length(program2)<=300. However, each program/function may be of different length.

Scoring

You will be scored based on how accurate your programs/functions were. Your score will be calculated based on the following formula:

Highest score wins. Ties are broken by shortest shared byte total.

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SANDBOX NOTES

• I can't help but fell like I am missing something.
• Should I post the gist contents here, as well as a link to it?
• Is 300 bytes too generous, too litte, or is it fine?
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Answer 30

How far is it?

I have no children myself but I understand they are more interested in the destination than the journey, so often ask how much of the journey is left. This might be a car trip, or it might be a demonstration of the Tower of Hanoi puzzle.

The original aim of the puzzle is to move all the disks from one pillar to another, but except for the smallest disk (which can be moved to any pillar at any time) the only disk you can move is the lowest numbered disk on the other two pillars.

Although there is a well-known optimal sequence from one pillar to another, each of the three moves will take you slightly nearer to finishing on a different pillar. (This partly explains why there are only two available moves when all the disks are already on the same pillar.) It's therefore possible to mistakenly take a detour towards another pillar yet correct yourself and finish at your desired pillar without retracing your steps. You should therefore not assume that the input position is from the optimal sequence.

The challenge is to write a program or function that accepts three sets (arrays, lists, strings, etc.) representing the sizes of the disks on each pillar and returns an integer giving the number of steps remaining to move all the disks to the first pillar. Examples:

[1, 2, 3] [0] [] -> 1
[2, 3] [0, 1] [] -> 3
[0, 1] [2] [3] -> 11
[0, 1, 2] [] [3] -> 15

Not only must your program return the shortest number of steps possible, but it must itself also be as short as possible.

Please indicate whether your input format requires the disks in a particular order.