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

Output The End Poem. Outputting as array, or with only one \n or three \n to separate sentences, etc. are fine. Shortest code win.

Upvote to prefer: You can take an input containing all letters in lowercase or uppercase

Downvote to prefer: You can take an input containing all letters in their original cases(upper/lower)

P.S. The two old choices are too similar

Comment if duplicate, fell the length is bad, etc

Answer 2

Sums of Bessel Polynomial Coefficients [WIP]

This is https://oeis.org/A001515.

Interesting alternate characterizations include:

Equivalently, number of sequences of n unlabeled items such that each item occurs just once or twice (cf. A105749). - David Applegate, Dec 08 2008

Numerator of (n+1)-th convergent to 1+tanh(1). - Benoit Cloitre, Dec 20 2002

a(n) is also the numerator of the continued fraction sequence beginning with 2 followed by 3 and the remaining odd numbers: [2,3,5,7,9,11,13,...]. - Gil Broussard, Oct 07 2009

Also, number of scenarios in the Gift Exchange Game when a gift can be stolen at most once.

Answer 3

Is the array sorted?

Inspired in part by Creative ways to determine of an array is sorted.

Given an array of integers, find out if the array is sorted. This challenge is as simple as it sounds. I'm surprised that I couldn't find a question like this on PPCG. I'm aware that a lot of golfing languages will have short solutions, but perhaps this question could allow you to showcase a language that's more esoteric than it is practical?

Input

An array of integers, or a sequence of integers if your language doesn't support arrays.

Output

Truthy if the array is sorted, falsey otherwise

Examples

[1, 2, 3] => true
[3, 2, 1] => false
[1, 1, 1] => true
[] => true
[1] => true
[-3, -2, -1] => true
[-1, -2, -3] => false
[1, 2, 1] => false
[1, 1, 0] => false

Since this is code-golf, get ready to trim off some bytes! Happy golfing!

For the sandbox

I have searched thoroughly for a question like this, but I haven't been able to find this question posted previously. If it exists, or if it is too similar to another question, please link the question or comment why this question should/shouldn't be posted.

decision-problemcode-golfintegersorting

Answer 4

Compressed RSA keys

cops-and-robbers number-theory primes

Silly cops-and-robbers idea.

As computers get more powerful, RSA keys have grown longer and longer to maintain security. This makes it difficult to:

• hand out your encryption key on business cards
• recite it over the telephone
• quickly scribble it down when you meet someone at a bar
• etc.

But we are all programmers (maybe even that someone that you met in a bar), so let's come up with RSA keys that can be generated by very short programs. We should be careful, though, that these keys remain resistant to cracking.

Cops

Write a short program (or function) that outputs an RSA key. For this challenge, an RSA key is just any positive integer less than \$2^{1024}\$ that has a non-trivial divisor.

Your program must:

• take no input
• output the same number every time it's run
• finish quickly (a few seconds at most)

Post your program, its language, and what it outputs.

Also, prove that you can use it as an RSA key. Provide a SHA-256 hash of a string that lists all the prime factors of your key.

Robbers

Crack the RSA keys! If an RSA key is the integer \$n\$; find any integer \$1<d<n\$ that divides \$n\$.

Scoring

A key is vulnerable to cracking for 7 days after it's posted. After that, it is considered safe and eligible for scoring.

Cops: The shortest uncracked program wins.

Robbers: Most cracks wins.

(Related: compress RSA public keys on crypto.SE)

Answer 5

Not a challenge, but not certain of the wording so trying it out here:

---

Tips for golfing in JSLint

tips javascript code-golf

---

What general tips do you have for golfing in JavaScript restricted to satisfying JSLint with default options? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to JSLint (e.g. "remove comments" is not an answer).

Answer 6

Unjagged my array

fastest-code

---

Given a jagged array of integers, rearrange the integers such that

• The shape of the jagged array is unchanged, and

• The jaggedness of each subarray is minimized.

Here "jaggedness" is defined as the sum of the absolute differences in each subarray. If an array has only one element, then the jaggedness of that array must be 0, since there are no absolute differences to consider.

We only care about the differences in elements in the same subarray. So for example:

[[1, 2], [100]]

has a jaggedness of 1, since the first array has a jaggedness of \$abs(1-2) = 1\$ and the second array has a jaggedness of 0. We don't care that the difference between 2 and 100 is 98 since they are different subarrays.

Here's an example:

Input: [[16, 8], [15], [4, 42, 23]]
jaggedness of input: [abs(16 - 8)] + [0] + [abs(4 - 42) + abs(42 - 23)] =
8 + 38 + 19 = 65

One possible output: [[4, 8], [42], [15, 16, 23]]
jaggedness of this output: [abs(4 - 8)] + [0] + [abs(15 - 16) + abs(16 - 23)] = 4 + 1 + 7 = 12

Of course, this is one possible output. Any of these outputs would also have a jaggedness of 12:

[[4, 8], [42], [23, 16, 15]]
[[8, 4], [42], [15, 16, 23]]
[[8, 4], [42], [23, 16, 15]]

Clarifications

• The input will always contain non-negative integers. The input will also always have a length >= 1, and all of the subarrays will have a length >= 1. This means that you must handle inputs as small as [[n]], where n is any non-negative integer.

• If the input is already arranged to be as smooth as possible, it is acceptable for your code to output the integers in a different order, as long as this new order has the same jaggedness. For example, if the input was

  [[1, 2], [3, 4, 5]]
  

  then your program may return the input unchanged, or it may return

  [[5, 4], [1, 2, 3]] 
  

  or any of the other arrangements with jaggedness 3.

Fastest code

This is a fastest-code challenge, so the submission with the shortest run time for a hidden test case will win. I will use 2 different test cases with different shapes, and your score will be the sum of the time for each. (I haven't yet decided how large these test cases should be. I might adjust them once submissions come in so that it takes an appropriate amount of time.)

All submissions will be tested on my machine:

• Windows 10
• i7-4790k
• 8 GB RAM

You can use any language that is freely available on Windows 10. Please also provide instructions for running your submission. I will test each submission at my soonest convenience after it's posted, and then comment an unofficial score. After 1 week, I will test every submission, and post a leaderboard.

Test Cases

These test cases were generated with and verified by a python brute-forcer.

Input: [[1, 2, 9], [10, 11]]
Output: [[9, 10, 11], [1, 2]] (jaggedness 3)

Input: [[4, 8, 15], [16], [23, 42]]
Output: [[4, 8, 15], [16], [23, 42]] (jaggedness 30)

Input: [[45, 98, 9, 46], [48, 53, 59], [13], [38, 94]]
Output: [[45, 46, 48, 53], [9, 13, 38], [59], [94, 98]] (jaggedness 41)

Note that none of these test cases show the only acceptable answer, merely one acceptable answer. For example, any output would remain valid if a subarray was reversed.

Answer 7

Destroy the Computers with Magnets!

The robot apocalypse has finally arrived. But as we all know, robots are controlled by computers. And magnets are a convenient way of disabling computers.

Your task: place the magnet close enough to the computer so that it disables the computer.

A computer looks like this (always the exact same size):

 ____
|    |
|    |
|____|

The magnet looks like this:

o

The magnet needs to be touching the computer to do its work:

 o____o
o|    |o
o|    |o
o|____|o
 oooooo

Note the lack of placements on the top; that is intentional. People use the computer on that side, and would easily see the magnet and remove it.

So if you are given a picture of some computers:

       ____
      |    |
 ____ |    |
|    ||____|
|    |      ____
|____|     |    |
           |    |
           |____|

You should place 1 magnet for computer next to the computers:

       ____
      |    |
 ____ |    |
|    ||____|
|    |  o   ____
|____|     |    |
 o        o|    |
           |____|

Magnets may touch computers, but there must be 1 touching magnet per computer.

Due to the apocalypse, resources are scarce, so your program to place magnets must be as short as possible.

Test cases:

Input
~~~~~
Example outputs (not only possible outputs)
=====
       ____
      |    |
 ____ |    |
|    ||____|
|    |      ____
|____|     |    |
           |    |
           |____|
~~~~~
       ____
      |    |
 ____ |    |
|    ||____|
|    |  o   ____
|____|     |    |
 o        o|    |
           |____|

        ____
       |    |
  ____ |    |o
 |    ||____|
 |    |     o____
o|____|     |    |
            |    |
            |____|
=====
More soon....

Answer 8

Minimal Substring Lookup Table

A fairly common component of code golf challenges is taking input as a string, and finding the index of that string within an array. A common way to golf that action is to instead store a substring of each item in the array, and take the same substring of the input to use when looking up the index. For example, this question has some fairly large strings that need to be indexed, but this answer found that each item could be uniquely identified by its 4th letter.

Challenge

Find the shortest substring that, when applied to each string in the input, results in a new set of unique strings.

Input

• Input is list of strings in any default format
• The strings will consist of printable ASCII characters.
• The strings will not have trailing spaces
• There will be no duplicate strings

Output

• Output should be a list of the shortened strings after applying the substring
• If outputting indexes, 0-indexing or 1-indexing may be used.
• When strings have different lengths, substrings exceeding the length of some lines may be handled any of these ways:
  • Truncate to the available characters, e.g. ["abc","acd","ab"] => ["bc","cd","b"]
  • Pad shorter strings with spaces, e.g. ["abc","acd","ab"] => ["bc","cd","b "]. Note that input strings can contain spaces which need to be taken into account, so ["ab c","acdc","ab"] must not become ["b ","cd","b "].
  • Wrap back to the start of the shorter string, e.g. ["abc","acd","ab"] => ["bc","cd","ba"]. Note that even with this method it is not necessary to look for substrings where every string wraps; the starting index should always be within the length of the longest input string.

Sandbox questions

• Should I restrict the input strings to only a subset of printable ASCII?
• Should I enforce one specific behavior for handling shorter strings? Requiring wrapping would let the challenge look for even shorter solutions requiring full wrapping, e.g. ["aba","ab"] => ["a","b"], but I don't want languages with different default substring implementations to need a lot of work just to get the wrapping working.
• I used the term "substring" as something that is "applied" to a string to get the shortened version, but I know that's extremely wrong. Is there a better way to phrase this?
• This challenge is related, but uses arbitrary substrings rather than aligned substrings. Should I mention it somewhere?

Answer 9

Piano Scale Fingering

There are 12 different major scales on the piano, which have similar, but not identical, fingering. Furthermore, the fingering for each hand is slightly different.

The fingers of each hand are numbererd starting at 1 for the thumb. Each note usually takes the next finger in turn. For the left hand playing an ascending scale, this means that the numbers decrease, while for the right hand the numbers increase.

Of course you will run out of fingers before you get to the end of the scale. For the left hand, this means that when you get to the thumb you need to start again with one of the other fingers, while for the right hand this means that when you get to a certain finger you need to start again with the thumb.

Although there are eight notes in an octave, the part that repeats in the middle of a scale is seven, which is a prime number. Scales are therefore normally played using the repeatying sequnces 4321321 in the left hand and 1231234 in the right hand; the little finger is only used to avoid switching to the thumb on the first or last note respectively. Other adjustments also apply at the very start and end of the scale.

There are a couple of rules which work for most scales. The first rule is that you try to play the tonic with the thumb except at the appropriate end of the scale when you use the little finger. If you can't follow that rule then with the right hand you use the thumb when switching from a black note to a white note; with the left hand you aim for the thumb to land on a white note just before a black note.

Here is a full list of all 12 keys and their fingerings:

 #  Key Left Hand       Right Hand
-6  Gb  432132143213212 234123423412345
-5  Db  321432132143212 231234123123412
-4  Ab  321432132143212 231231234123123
-3  Eb  321432132143212 212341231234123
-2  Bb  321432132143212 212312341231234
-1  F   543213214321321 123412341231234
 0  C   543213214321321 123123412312345
 1  G   543213214321321 123123412312345
 2  D   543213214321321 123123412312345
 3  A   543213214321321 123123412312345
 4  E   543213214321321 123123412312345
 5  B   432143213214321 123123412312345
 6  F#  432132143213212 234123123412345

Please write a program function which takes as input the key (or #, which is the number of sharps in the key, or the negation of the number of flats in the key) of a scale and a flag (e.g. L or R) for which hand, and output the fingering for two octaves as above. (For longer scales you simply repeat the middle 7 digits so I don't see the utility of asking you to output an arbitrary number of octaves.)

Note that Gb is enharmonic to F# on the piano but you might find it easier to support one rather than the other. Please indicate which one your answer supports.

As an alternative to writing a single function I will also allow two named functions (one for each hand) but not two lambdas. The 1 byte per extra file penalty applies if you submit two full programs.

Answer 10

Front lines go front! code-golf array-manipulation

Given two lists of positive integers, bring the elements in the first one that are in the second to the far left, keeping their order the same as in the first list. You can assume that the second list's elements will all be unique.

These approaches are forbidden.

For example, let's call the first list \$A\$ and the second \$B\$. Here are some test cases:

\$A=[1,3,4,1,2,1,4,3,2,1,3,2,4,1],B=[1,3]\rightarrow[1,3,1,1,3,1,3,1,4,2,4,2,2,4]\$

\$A=[],B=[1,4,5]\rightarrow[]\$

\$A=[1,2,3,4,5,6,7,8,10],B=[]\rightarrow[1,2,3,4,5,6,7,8,10]\$

\$A=[],B=[]\rightarrow[]\$

\$A=[1,2,2,1,3,4,4],B=[1,2]\rightarrow[1,2,2,1,3,4,4]\$

\$A=[3,4,4,1,2,1,5],B=[1,5,2]\rightarrow[1,2,1,5,3,4,4]\$

\$A=[1,2,3,2,1,2,3,2,1],B=[4,5,6]\rightarrow[1,2,3,2,1,2,3,2,1]\$

\$A=[2,2,1,2,1,3,3,1,4],B=[1,2,3,4]\rightarrow[2,2,1,2,1,3,3,1,4]\$

Note: the integers aren't necessarily single-digit.

Answer 11

Do not not not not make a filter that doesn't not not not get rid of these words!

Tags: code-golf

Your program has to scan each run of "not"s in a sentence, and if the number of "not"s is odd, then replace it with only one "not". If it is even, replace it with the empty string.

Notes:

• The "not"s are case-insensitive, so your input may be "not" or "Not" or more.
• The input may only be taken in as a string.

Test cases:

 Don't not not -->  Don't
 not not not a not not  -->  not a
 NoT nOt not NOT noT a Not nOt noT  -->  not a not
hello notnot anot not anota not not not --> hello a anota not

Answer 12

Radiation Showdown KotH

In radiation hardening challenges, the goal is to write a program whose behavior doesn't change when an arbitrary character is removed from its source. This KotH explores an adversarial variant on this challenge in which two programs compete to survive the most character deletions. The twist is that each program is provided the source code of its opponent and outputs which character should be deleted from its opponent's source code next.

Gameplay

Suppose program A and B are competitors.

1. Each program is run and the output is recorded. Let the output of program A be a and the output of program B be b. If one program fails to output a valid character index of its opponent's source code, the other program will be declared the winner of the match. If neither program outputs a valid index, then a tie is declared.
2. The a'th character is removed from program B and the b'th character is removed from program A.
3. Repeat steps 1 and 2 until there is a winner or a tie.

Submissions

Submissions should be a complete javascript or python program which:

• Begins with a shebang (#!) indicating which language it is written. For python entries, this should be #!/usr/bin/python. For javascript entries this should be #!/app/.heroku/node/bin/node.
• Takes three command line arguments: the code for the opponent program, the start of the range of deletable characters (x), and the end of the range (y). In python these can be accessed using sys.argv, while in javascript they can be found in process.argv.
• Prints a number in the range [x,y) to stdout and terminates in less than 10 seconds.

Note: The index of the first deletable character of your opponent's program (x) is the index of the first character after the shebang. y is the length of the opponent program in characters (so y-1 is the last deletable character).

Sample Submissions

Python:

#!/usr/bin/python
import sys

# vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
print (sys.argv[3]-1)
# vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

Javascript:

#!/app/.heroku/node/bin/node
// vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
console.log(Math.round(Math.random() * process.argv[4]));
// vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

Controller

I've hosted a web based controller at https://radiationshowdownkoth.herokuapp.com/. It should conform to the behavior specified in the Gameplay section. Let me know if you find any bugs.

Rules

• Standard loopholes apply.
• The use of preexisting interpreters and their components (parsers, lexers, etc) is banned. This includes, but is not limited to, calling the python and node binaries from your program (eg os.popen("python -c ...")), using builtin eval functions (eg python's exec), and using relevant modules (such as python's astlib). However, you may use regular expressions.
• No malicious code.

Logistics

It will be a Round Robin Tournament. Each submission will be matched against every other submission. For each victory a submission achieves, it will be awarded 1 point. Likewise, ties are worth 0.5 points and losses are worth 0 points. The submission with the most points after all rounds have been completed wins this KotH. The winner will receive a bounty from yours truly, and the most popular entry will be awarded accepted answer. This KotH will be open to entries for a week following its posting, at which point the tournament will be run and a winner declared.

Meta

• Duplicate?
• Clarifications?
• Other Language Suggestions besides Python & Javascript?
• Are there any trivial strategies that would be overwhelmingly effective?
• Any other foreseeable problems?

Answer 13

Unfactor a list code-golf jelly math number primes

Jelly has an interesting built-in, ÆẸ. It's the inverse of ÆE. ÆE returns the exponents of the prime factors of an integer n, where each exponent corresponds to the prime number at its index, so, for example, [3, 5, 1] represents \$2^3\cdot3^5\cdot5^1\$. If a prime isn't included in the prime factorization of n, but there is at least one prime after it that is included, a zero is put in its place (\$p^0=1\$). So, for example, [3, 0, 5, 1] represents \$2^3\cdot5^5\cdot7^1\$, and [0, 4, 4, 50, 0, 7] represents \$3^4\cdot5^4\cdot7^{50}\cdot13^7\$.

Your job is to implement ÆẸ, ÆE's inverse. That is, you'll be given a list returned by ÆE, and your job is to find n.

You must always return a positive integer (strictly greater than zero). You may assume the input doesn't have negative or float exponents or trailing zeroes.

Note that you're encouraged not to use ÆẸ or your language's equivalent (if any) in your answer.

Using any of the standard loopholes is prohibited.

Test cases (you don't have to support exponents, an output or an input's length beyond your natural signed integer type's limit):

[] -> 1
[0, 4] -> 81
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] -> 1111
[10] -> 1024
[3, 5, 1] -> 9720
[3, 0, 5, 1] -> 175000
[31] -> 2147483648
[32] -> 4294967296
[63] -> 9223372036854775808
[64] -> 18446744073709551616
[0, 4, 4, 50, 0, 7] -> 5713082599062385095715588395684396863698753591853983125

Make more test cases:

To generate the input that corresponds to a given output, use this program.

To generate the output that corresponds to a given input, use this program.

Answer 14

Where can I get to from each location? (Transitive Closure)

Given an undirected graph (network) \$G\$, construct a new graph in which vertex (node) pair \$(u,v)\$ is an edge (are connected) if and only if a path \$(u,w_1,w_2,...,w_k,v)\$ exists in \$G\$ for some \$k\ge 0\$. This is known as \$G\$'s transitive closure. If this is clear to you, you're ready to get started. Otherwise, just read through the below sections. It is actually a very simple problem.

I/O formats

Take for example the graph (network)

1──2  3──4
│     │
5  6──7──8

We can represent¹ it as an adjacency (connection) matrix:

 │1 2 3 4 5 6 7 8
─┼───────────────
1│  ┘ 
2│
3│      ┘
4│
5│┘
6│            ┘
7│    ┘         ┘
8│

which is:

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

Note that here only one of \$(u,v),(v,u)\$ is represented, but we consider both directions as valid edges (connections).

Or as a list of of edges²:

[[1,2],[1,5],[3,4],[5,1],[6,7],[7,3],[7,8]]

Or for each vertex³ (node), the list of its adjacent vertices:

[[2,5],[1],[7,4],[1],[7],[3,8],[8],[]]

Or as a dictionary⁴:

{"1":[2,5],"3":[7,4],"7":[6,3,8]}

Any of these, and any other reasonable input and output formats (you optionally may use one format for input and another for output) are allowed, but you must state what your formats are. However, it is required that your formats support under-representing (e.g. [3,7] but not [7,3]) and over-representing (e.g. both [3,7] and [7,3]).

Walk-through

Let's use the representation [[1,2],[1,5],[3,4],[5,1],[6,7],[7,3],[7,8]]. Since 1 is connected to 2 then 2 is also connected to 1, so we add (it doesn't matter where) this edge (connection):

[[1,2],[1,5],[2,1],[3,4],[5,1],[6,7],[7,3],[7,8]]

It is also possible to travel [1,5] in reverse, but that pair is already represented further in the list. Now note that it is possible to find a path from 2 to 5, and vice versa, via 1, so we add these two edges:

[[1,2],[1,5],[2,1],[2,5],[5,2],[3,4],[5,1],[6,7],[7,3],[7,8]]

This completes the left side of the graph. Similarly, we process the right side by adding the reversals of [3,4], [6,7], and [7,3]:

[[1,2],[1,5],[2,1],[2,5],[5,2],[3,4],[5,1],[6,7],[7,3],[7,8],[4,3],[7,6],[7,3]]

Two-step paths via 3 are possible, so we add [7,4] and [4,7]. Similarly, two-step paths via 7 are [6,3], [3,6], [6,8], [8,6], [3,8], and [8,3]:

[[1,2],[1,5],[2,1],[2,5],[5,2],[3,4],[5,1],[6,7],[7,3],[7,8],[4,3],[7,6],[7,3],[7,4],[4,7],[6,3],[3,6],[6,8],[8,6],[3,8],[8,3]]

Finally, we add the three-step paths [6,4], [4,6], [4,8], and [8,4]:

[[1,2],[1,5],[2,1],[2,5],[5,2],[3,4],[5,1],[6,7],[7,3],[7,8],[4,3],[7,6],[7,3],[7,4],[4,7],[6,3],[3,6],[6,8],[8,6],[3,8],[8,3],[6,4],[4,6],[4,8],[8,4]]

And this is our answer. It could of course be in any order.

---

1. ^{Though the connections do not have direction, I've only put in one entry in the table for each connection, and obviously the diagonal is all-true too, as every node is reachable from itself.}
2. ^{Since the connections in this challenge do not have a direction, [1,5] and [5,1] are the same connection. This serves to illustrate that such may occur in the given data.}
3. ^{Here, each node must have its own list, as the lists are paired to their points by their position in the data. However, each list need not be exhaustive as long as all connections are represented somewhere.}
4. ^{Here, we can omit entries that are fully covered by the other entries.}

code-golf path-finding graph-theory

Answer 15

"Cumbersome Crown words"

Introduction

This is my first entry here, so please be gentle if it's poorly stated. I'll need a bit of guidance to make it a good submission.

I am a typewriter maker, and I want to prove that the design of my competitor, Mr. Crown, is very inconvenient to use. To do that, I want a list of the most cumbersome words to type out on a Crown typewriter.

Challenge

Write a program that takes an argument "n" as a positive integer. You may load the Unix words list from any source (ignore case; discard any word containing anything outside of A-Z, such as "O'Brien", "L'vov", etc.). Given the layout shown below, output the "n" most cumbersome words to write, one result per line. Each result is the cumbersome word, some form of separator (eg. a space), then their word score (see below) with two decimals of precision (and your choice of decimal separator). Bonus if results are sorted in descending order by their word score, and further bonus if ties (by score) are also sorted in alphabetic order.

X Q K G B P M C O F L A N D T H E R I S U W Y J V Z

Word scoring

Assume the pointer starts in the leftmost position, on "X". Count each movement and each hammer strike as one unit, but divide the sum by the number of characters in the word. Hence, sample word scores are:

• THEIR: 4.8 -- 24 units (14 movements, strike "T", movement, strike "H", movement, strike "E", 2 movements, strike "I", movement, strike "R") divided by 5 characters
• LAND: 4.25 -- 17 units (10 movements, strike "L", movement, strike "A", movement, strike "N", movement, strike "D") divided by 4 characters
• FOWL: 9.50 -- 38 units (9 movements, strike "F", movement, strike "O", 13 movements, strike "W", 11 movements, strike "L") divided by 4 characters
• BARBARA : 8.00 -- 56 units (4 movements, strike "B", 7 movements, strike "A", 6 movements, strike "R", 13 movements, strike "B", 7 movements, strike "A", 6 movements, strike "R", 6 movements, strike "A") divided by 7 characters
• X: 1 -- just hit the hammer once and you're done

Note: These examples are not the most cumbersome words.

Example Input and Output

Input:

5

Standard output:

ANNA 4.25

THEIR 4.80

LAND 4.25

BARBARA 8.00

FOWL 9.50

Bonus output:

FOWL 9.50

BARBARA 8.00

THEIR 4.80

ANNA 4.25

LAND 4.25

Scoring submissions and determining the winner

I'm really not sure what the best measure of success is. Definitely not code golf, because I can never distinguish the damn things from line noise or pure black magic. But what then? I'm not very familiar with which competition types are available.

If two solutions are tied for a position, but only one of them uses the bonus output format, then that one wins the tie.

Answer 16

My Number is Bigger Than Yours: KoTH

The concept of this game is simple; each turn, two bots submit a positive integer (in Python, so no upper bound on its size). Whichever bot submits a larger number wins a certain number of points based on the scoring put forward in the next section. This process is iterated a certain number (100?) times to form the competition, with the bot which has the highest score winning the competition between the two bots.

However, scoring is based on some metric of the difference between the submitted values such that the larger the difference is, the smaller the amount of score gained is. I'm trying to decide some metric which heavily incentivizes making a guess which narrowly beats your opponent's guess, maybe with a metric such as 1/(a-b)**2. However, as the numbers will likely grow throughout the iterations, maybe 1/(a/b)**2 might be better.

Example bot whose goal is to beat opponents who pick a constant number:

def constant_beater(my_score, opp_score, my_numbers, opp_numbers):
    if len(opp_numbers) == 0:
        return 1
    return opp_numbers[-1] + 1

The largest concern I see with this challenge is a bot which just increments much quicker than all other bots so that it wins every game with a minuscule amount every time. Maybe to curb this a score that is below a certain threshold for a game is rounded to zero to encourage more competitive choices.

Answer 17

Drawing \$K_n\$ (complete graph with \$n\$ vertices)

Tags: code-golf, graph-theory, graphical-output

---

In graph theory the complete graph with \$n\$ vertices, often written as \$K_n\$, is the graph where every vertex is connected to every other vertex. For example, \$K_3\$ with \$V = \{A,B,C\}\$ has the edges \$\bigr\{\{A,B\},\{B,C\},\{C,A\}\bigl\}\$ - forming a triangle.

Challenge

Given an even \$n \geq 4\$ you will generate/display an image of the graph \$K_n\$ as follows:

• pick an image width \$\texttt{width} \geq 100\$
• pick two distinct colors \$\texttt{vertex_color}\$ and \$\texttt{edge_color}\$
• draw \$1\$ vertex with color \$\texttt{vertex_color}\$ in the middle of the image
• draw the remaining \$n-1\$ vertices evenly distributed on a circle around it
• connect every vertex with color \$\texttt{edge_color}\$

Rules

• the background color doesn't matter (transparent is fine), but it must not coincide with the colors \$\texttt{vertex_color}\$ and \$\texttt{edge_color}\$
• the radius of the circle should be \$\texttt{width/4}\$
• the center of the circle should the middle of the image
• the shape of the vertices doesn't matter, but they must be at least \$3\$ pixels wide
• the edges must not overlap the vertices
• the edges may be dashed, dotted etc.

Examples

Example output for \$K_4\$:

Example output for \$K_{12}\$:

Example output for \$K_{32}\$:

Answer 18

Chain round the number!

A decimal place is a digit of a number's location in a number. In the number 987654321, each digit corresponds to its decimal place. For example, in the number 16111, the 6 is in the 4th decimal place.

Normally when rounding to n decimal places, one checks the digit at n-1 (heretofore called x). If x >= 5, then the digit at n is rounded up. Otherwise the digit at n is rounded down (stays the same). Then, all digits including and after x are turned into 0.

For example, take the number 158, rounded to the 3rd decimal place. The digit at the 2nd decimal place (3rd decimal place minus one) is 5. Because of this, the 1 at the third decimal place gets rounded up. This results in the number being 258. However, the 5 and the 8 both get turned into 0, and so the final result is 200.

Chain rounding is like normal rounding, except that you do it to every digit starting with the digit at decimal place 2. Once you round to the decimal place 2, then you round to decimal place 3, and so on until decimal place n.

For example:

Input: 24472
24472    (2 < 5, so the 7 rounds down)
24470    (7 >= 5, so the 4 rounds up)
24500    (5 >= 5, so the 4 rounds up)
25000    (5 >= 5, so the 2 rounds up)
30000    (Final answer. Non chain-rounded answer would be 20000)

The challenge here is to chain round a number to the highest decimal place possible for that number.

Test cases: (all inputs will be positive whole numbers)

24472 -> 30000
1999 -> 2000    ("1 9 9 9" -> "1 9 10 0" -> "1 10 0 0" -> "2 0 0 0")
9945 -> 10000
2001 -> 2000
9444 -> 9000
9445 -> 10000
13579 -> 10000
24681 -> 30000
1337 -> 1000
5 -> 10
1 -> 1

Answer 19

A Turtle Finds a Portal

The turtle wants to move along the grid to get to his food. He wants to know how many moves it will take for him to get there.

As well since he is slow he has teleporters set up around his domain that he will utilize if it shortens his path. Or avoid them if it lengthens his path.

Meet the turtle

🐢

The turtle lives on a grid $$\begin{matrix} X&X&X&X&X\\ X&X&X&X&X\\ X&X&🐢&X&X\\ X&X&X&X&X\\ X&X&X&X&X\\ \end{matrix}$$ The turtle can move to any adjacent square... $$\begin{matrix} X&X&X&X&X\\ X&\nwarrow&\uparrow&\nearrow&X\\ X&\leftarrow&🐢&\rightarrow&X\\ X&\swarrow&\downarrow&\searrow&X\\ X&X&X&X&X\\ \end{matrix}$$

However, the turtle cannot move to a square with a mountain $$\begin{matrix} X&🌄&X&X&X\\ X&\nwarrow&\uparrow&\nearrow&X\\ X&🌄&🐢&\rightarrow&X\\ X&🌄&\downarrow&\searrow&X\\ X&🌄&X&X&X\\ \end{matrix}$$

The turtle wants to eat his straw berry, and would like to know how long it will take to get to his strawberry $$\begin{matrix} X&🌄&🍓\\ 🐢&🌄&X\\ X&🌄&X\\ X&X&X\\ \end{matrix}$$ This example would take the turtle \$5\$ turns $$\begin{matrix} X&🌄&🍓\\ \downarrow&🌄&\uparrow\\ \searrow&🌄&\uparrow\\ X&\nearrow&X\\ \end{matrix}$$ To get around mountains the turtle uses his teleporter. There are two teleports on the grid that map to each other. Stepping on the teleporter immediately moves the turtle to the corresponding teleporter. $$\begin{matrix} 🔵&🌄&🍓\\ 🐢&🌄&🔴\\ X&🌄&X\\ X&X&X\\ \end{matrix}$$ It is now faster for the turtle to move up twice. Now the turtles shortest path is \$2\$ $$\begin{matrix} 🔵&🌄&🐢\\ \uparrow&🌄&🔴\uparrow\\ X&🌄&X\\ X&X&X\\ \end{matrix}$$

The challenge

Given an initial grid configuration output the number of moves it will take the turtle to reach his strawberry.

Rules

• You may assume that the input grid has a solution

• The input grid may be entered in any convenient format

• The shortest path does not need to make use of the portal

• The turtle cannot pass into mountain tiles

• The turn that the turtle moves onto a teleporter square he is already on the corresponding teleporter. He never moves onto a teleporter and stays there for a move

• You may use any ASCII character to represent mountains, turtle, empty gird square, strawberry.

• You may use either the same character or two different characters to represent the teleporter pairs

• A grid can have more than one path with the same shortest path length

• Each grid will only have one strawberry and two portals

• This is code-golf.

Test Cases formatted as lists

[ ['T', 'X', 'X', 'S', 'X'], ['X', 'X', 'X', 'X', 'X'], ['X', 'X', 'X', 'X', 'X'] ] --> 3
[ ['T', 'M', 'X', 'S', 'X'], ['X', 'M', 'X', 'X', 'X'], ['X', 'X', 'X', 'X', 'X'] ] --> 4
[ ['T', 'M', 'X', 'S', 'O'], ['O', 'M', 'X', 'X', 'X'], ['X', 'X', 'X', 'X', 'X'] ] --> 2
[ ['T', 'M', 'X', 'S', 'X'], ['O', 'M', 'X', 'X', 'X'], ['O', 'X', 'X', 'X', 'X'] ] --> 4
[ ['T', 'M', 'S', 'X', 'O'], ['X', 'M', 'M', 'M', 'M'], ['X', 'X', 'X', 'X', 'O'] ] --> 7

Test Cases formatted for humans

T X X S X
X X X X X
X X X X X --> 3

T M X S X
X M X X X
O X X X O --> 4

T M X S O
O M X X X
X X X X X --> 2

T M X S X
O M X X X
O X X X X --> 4

T M S X O
X M M M M
X X X X O --> 7

Credits

Design and structure via: Hungry mouse by Arnauld

Proposed Challenges Edit Advice: Kamil-drakari, beefster

Answer 20

Playing Pickomino

Answer 21

SLIPpery Packets

The Serial Line Internet Protocol is an early internet protocol, used to essentially escape any "packet END" bytes that may appear in a packet. It has since been replaced by the more sophisticated Point-to-Point protocol, however it is still preferred on microcontrollers and low-level devices due to its simplicity.

Your goal is to implement simplified encoding and decoding functions following this protocol as a function/program/subroutine/etc.

The following table lists the special bytes used:

Hex    Dec   ISO 8859-1   Abbrev  
0xC0   192   À            END      
0XDB   219   Û            ESC
0xDC   220   Ü            ESC_END
0xDD   221   Ý            ESC_ESC

(The ISO 8859-1 characters are for visualizing where non-ASCII bytes are in the string.)

Encoding follows this system, iterating through each byte:

• If the END byte appears in the packet, write ESC, ESC_END instead
• If the ESC byte appears in the packet, write ESC, ESC_ESC instead
• Otherwise, write byte verbatim
• At the end, an END byte is appended to the message, and it is returned

Some implementations, such as the reference C implementation from RFC 1055, prepend an END byte to the string to be sent. This is omitted here for simplicity.

Decoding follows in reverse:

• If ESC, ESC_END appears in the packet, write END instead
• If ESC, ESC_ESC appears in the packet, write ESC instead
• Protocol violations that involve ESC followed by a "bad byte" that isn't ESC_END or ESC_ESC should be handled by writing the "bad byte"
• The first END byte seen (not following ESC) is interpreted as the end of the packet. The decoded packet should be returned without the END byte. You are guaranteed to have at least one such END byte appear.

Input/Output

For encoding, input is a packet (string of bytes) and output is the encoded packet (string of bytes).

For decoding, input is a "byte stream" (string of bytes) and output is the (first) decoded packet (string of bytes).

Test cases

Inputs

''                --> 'À'
'test\n'          --> 'test\nÀ'
'testÀ'           --> 'testÛÜÀ'
'teÛst'           --> 'teÛÝstÀ'
'À'               --> 'ÛÜÀ'
'ÛÜÛÝÀÛ'          --> 'ÛÝÜÛÝÝÛÜÛÝÀ'

Outputs

'À'               --> ''
'testÀblah blahÀ' --> 'test'
'teÛÝstÀ'         --> 'teÛst'
'testÛÜÛÜÀ'       --> 'testÀÀ'
'ÛÝÜÛÝÝÛÜÛÝÀ'     --> 'ÛÜÛÝÀÛ'
'ÛÀÀ'             --> 'À'
'ÛµÀ¶'            --> 'µ'

Scoring

Your score is the sum of the number of bytes in your encoding and decoding functions (or programs, etc.)

---

I have also considered requiring functions to take a length of packet in bytes which is used in encoding and decoding (similar to RFC 1055), not requiring handling protocol violations (ex. RFC 1055), and not testing decoding packets that have an END byte as not the last byte. Your opinions on how restrictive this challenge should be are appreciated.

Answer 22

One circle, two inputs, eight outputs

code-golf geometry number pi

Given the values of only two quantities from the following eight quantities ​​(the rest is unknown):

1. Radius of circle: \$\displaystyle R\$
2. Diameter of the circle: \$\displaystyle D=2\times R\$
3. Circumference of the sector: \$\displaystyle C=2\times\pi\times R=\pi\times D\$
4. Area of the circle: \$\displaystyle A=\pi\times R^2\$
5. Angle of the sector: \$\displaystyle\alpha\$
6. Length of arc: \$\displaystyle LA=\frac{C\times \alpha}{360°}\$
7. Area of the sector: \$\displaystyle AS=\frac{A\times \alpha}{360°}\$
8. Perimeter of the sector: \$\displaystyle PS=LA+2\times R=LA+D\$

compute the rest of quantities if possible, else put special output (-1, False,...) if at least one of the quantities can not be computed.

Input

Two quantities with there values (non negative integers)

Output

The values of the eight previous quantities (decimal with any precision or rounded integer).

Example

In this example the inputs is the ordered list of the previous quantities. Values are integers, angles in degrees, and outputs as rounded integers.

[16, ?, ?, ?, 100, ?, ?, ?]   --> [16, 32, 100, 804, 100, 27, 223, 59]
[24, ?, ?, ?, ?, ?, ?, 58]    --> [24, 48, 150, 1809, 23, 10, 120, 58]
[28, ?, ?, ?, ?, ?, ?, 188]   --> [28, 56, 175, 2463, 270, 132, 1848, 188]
[?, 18, ?, ?, ?, ?, ?, 41]    --> [9, 18, 56, 254, 146, 23, 103, 41]
[?, 28, ?, ?, ?, ?, ?, 808]   --> [14, 28, 87, 615, 3191, 780, 5460, 808]
[?, 88, 220, ?, ?, ?, ?, ?]   --> False
[?, ?, 88, ?, ?, 84, ?, ?]    --> [14, 28, 88, 616, 343, 84, 588, 112]
[?, ?, 220, ?, ?, 66, ?, ?]   --> [35, 70, 220, 3851, 108, 66, 1155, 136]
[?, ?, ?, 50, 50, ?, ?, ?]    --> [3, 7, 25, 50, 50, 3, 6, 11]
[?, ?, ?, 254, ?, ?, 18, ?]   --> [8, 17, 56, 254, 25, 4, 18, 21]
[?, ?, ?, 707, 75, ?, ?, ?]   --> [15, 30, 94, 707, 75, 19, 147, 49]
[?, ?, ?, ?, 99, 24, ?, ?]    --> [13, 27, 87, 606, 99, 24, 166, 51]
[?, ?, ?, ?, 140, ?, 175, ?]  --> [11, 23, 75, 450, 140, 29, 175, 53]
[?, ?, ?, ?, 324, 85, ?, ?]   --> [15, 30, 94, 709, 324, 85, 638, 115]
[?, ?, ?, ?, 324, ?, 3465, ?] --> [35, 70, 219, 3850, 324, 197, 3465, 267]
[?, ?, ?, ?, ?, 66, 88, ?]    --> False

Rules

• The input and output can be given in any convenient format.
• Specify in the answer the special output when quantities can not be computed all.
• Specify in the answer whether the angle is in degree or radian or other unit.
• π can be set to 3.14 or 22/7 or 355/113 or any more precise value.
• No need to handle invalid input 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 online 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 23

Gregorian-Hijri(Islamic) Calendar Conversion code-golfcalendar

Introduction

The Hijri, or Islamic calendar is a lunar calendar used in the Islamic countries to determine the dates of traditional events. The year in the Hijri calendar is usually denoted AH xxxx. The Hijri calendar has an epoch on 16 July 622 on Julian calendar.

Like other lunar calendars, in the Hijri calendar a year consists of 12 months, each month consists of 29 or 30 days. A year is thus 354 days, or in leap years there are 355. On average there are 11 leap years every 30 years.

There is a tabular variant which uses arithmetic calculations in place of astronomical observations to determine the dates. There is also a solar version of the Hijri calendar, which is used in Iran and Afghanistan.

In this challenge, only the tabular variant will be discussed.

The tabular Hijri calendar

All western dates below will be shown in (possibly proleptic) Gregorian even if the date is before 15 October 1582.

There are 12 months in each year in the Hijri calendar, with alternating 29- or 30-day periods. The odd months have 30 days, and the even months have 29 days (except for the 12th month Dhu al-Hijjah in leap years which also has 30 days). The month names are as follows (according to this Wikipedia template):

#    Name              Number of days
1    Muharram          30
2    Safar             29
3    Rabi' al-awwal    30
4    Rabi' al-Thani    29
5    Jumada al-awwal   30
6    Jumada al-Thani   29
7    Rajab             30
8    Sha'ban           29
9    Ramadan           30
10   Shawwal           29
11   Dhu al-Qidah      30
12   Dhu al-Hijjah     29 / 30 (in leap years only)

There are 11 leap years every 30 years. There are 3 versions to determine the leap years, but the most common version is to set the years with \$y\in\{2,5,7,10,13,16,18,21,24,26,29\}(\text{mod }30)\$ as leap years. (Be reminded that the calendar stars from year 1.)

The Hijri calendar has its first day (i.e. 1 Muharram 1) on 19 July 622.

As an example, we now convert the date 8 February 2019 into Hijri (Here we define a cycle to be 30 years):

1. Date: 8 February 2019
2. Dates from the Epoch: \$1396 \times 365 + 339 + 166 + 38 = 510083\$
   • There are 1396 (\$2019 - 623\$) full years, so \$1396 \times 365\$ days
   • There are 339 (\$349 - 14 + 4\$) leap years between 2 dates
   • There are 166 days between 19 June 622 to 1 January 623, and 38 days between 1 January 2019 to 8 February 2019
3. Cycle: \$510083 \div 10631 = 47\text{ (cycles) and }10426\text{ (days)}\$
   • One ordinary year is 354 days and there are 11 leap years in a 30-year cycle, so total days in a cycle is \$354\frac{11}{30} \times 30 = 10631\$
4. \$10427 - (354 \times 29 + 11) = 150\$, so this this is the 150th day of the 30th year in the 48th cycle, which is \$47 \times 30 + 30 = \text{(AH) }1440\$.
   • The subtraction has 18 \$354\$s and 11 \$355\$s, but there is not enough space to write it all.
5. \$150 - 30 - 29 - 30 - 29 - 30 = 2\$, so this is the 2nd day of the 6th month in the year AH 1440.

As a result the complete Hijri date of 8 February 2019 is 2 Jumada al-Thani 1440.

Challenge

Write a program or function that converts the (Gregorian) input date into the corresponding Hijri date.

The program or function may receive the input date in any reasonable format, but it must output the Hijri date in the format of [date] [month name] [year]. The italics above shall be ignored.

The input month and day may be 0-indexed for convenience, but you must state so if you use this convention.

You may assume that the input is always a valid Gregorian date, and is always not earlier than the Gregorian epoch of the calendar, 19 July 622.

Sample I/O

Input:  "19 July 622" / "622-7-19" / [622, 7, 19] / (622, 6, 19) (0-indexed month)
Output: "1 Muharram 1" (The epoch date)

Input:  "8 February 2019" / "2019-2-8" / [2019, 2, 8] / (2019, 1, 8) (0-indexed month)
Output: "2 Jumada al-Thani 1440" (The example date)

Input:  "12 August 2019" / "2019-8-12" / [2019, 8, 12] / (2019, 7, 12) (0-indexed month)
Output: "10 Dhu al-Hijjah 1440" (The start date of Eid ul-Adha in AH 1440)

Input:  "9 August 2021" / "2021-8-9" / [2021, 8, 9] / (2021, 7, 9) (0-indexed month)
Output: "30 Dhu al-Hijjah 1442" (The next leap day)

Winning Criteria

As this is a code-golf, shortest answer of each language wins. Standard loopholes are banned by default.

Answer 24

Unique Skittle Pairs

code-golf This is my first question, so hopefully it's OK.

I like to eat Skittles. However, I only like to eat them in pairs, and and those pairs must not have two Skittles of the same color. Your task is to find the most pairs that you can that match these requirements.

Challenge

Input (taken from standard input) is a set of Skittles formatted like so: pyyyggoooorr, where p is purple, y is yellow, g is green, o is orange, and r is red. The number of letters for each color corresponds to the number of Skittles that are that color. The only colors used in this challenge are purple, yellow, green, orange, and red. The input will always be even in length and lowercase.

Output is the most possible pairs of Skittles that I like to eat given the input. Different outputs don't matter as long as they are valid, i.e. for an input of pygo, both py go and po gy are valid outputs. Output for invalid input doesn't matter.

The output must be in the same format as the test cases.

Examples/Test Cases

Permutations of these solutions are valid. You do not have to output all valid outputs. Multiple output lines here means multiple valid outputs.

> ppyy
py py

> yggooo
yo go go

> pyygorrr
pr yr yg or
py yr gr or

> yggoor
yg go or
yo go gr
go go yr

> yggor
(anything, including no output/errors)

> gygoro
yg go or
yo go gr
go go yr

> ygoOor
(anything, including no output/errors)

> ggorrrrr
gr gr or

> pppyyygggooorrrr
py py py ro ro ro rg
po po po ry ry ry rg
py po py ro ry ro rg
etc.

Least bytes wins.

Answer 25

Sort according to cyclic order

Cyclic order on a set is a function f taking three distinct elements of a set, returning bool and having following properties:

1. If f(a, b, c) then f(b, c, a)
2. If f(a, b, c) then not f(c, b, a)
3. If f(a, b, c) and f(a, c, d) then f(a, b, d)
4. One of f(a, b, c) and f(c, b, a) is true

Values of f when arguments are not distinct don't matter. You are given a list of dictinct numbers and a function f posessing the above properties when arguments are taken from the list. Your task is to arrange the numbers in such an odrer that

f(a, b, c) if and only if k > j > i or i > k > j or j > i > k

(i.e. numbers a, b, c come in that order modulo cyclic permutaion)

Score is the total number of calls to the function f on some dataset.

It's not very clear to me how to create the dataset and how to count calls to f across different languages. Is it better to just give a list of n*(n-1)*(n-2) values of f as input (and score by bytes)?

Answer 26

Venn of \$n\$ number of sets

Given positive integer \$n\$, output \$n\$ 2D bool images with same width and height such that:

1. each image should be 4-connected, i.e. for each two pixels that are true, you can start from one and go up, down, left and right for some times to the other pixel, only passing through true pixels.

2. each image should have no hole, i.e. the component should be 4-connected

3. If we choose itself, its component or neither for each image, their intersection should be non-empty and 4-connected

Examples (only a finite amount of solution shown, but there are infinitely many more)

Input: 1

Output:

.....
.***.
.**..
..*..

Input: 1

Output:

.....
...*.
.....
.....

Input: 2

Output:

..... .....
.***. ..**.
..... ..**.
..... .....

Input: 2

Output:

..... .....
.**.. ..**.
..**. ..**.
..... .....

Input: 3

Output:

..... ..... .....
.**.. ..**. .....
.**.. ..**. .***.
..... ..... .***.

Input: 4

Output:

...**.. .***... ....... .......
...**.. .***... ..***.. .......
...**.. .***... ..***.. ..****.
....... .***... ....... ..****.
....... ....... ....... ..****.
....... ....... ....... .......

Shortest code in each language win

Reference

Answer 27

Data.List.nub :: Eq a => [a] -> [a]

Tags: code-challenge, haskell, list

---

O(n^2). The nub function removes duplicate elements from a list. In particular, it keeps only the first occurrence of each element. (The name nub means `essence'.) It is a special case of nubBy, which allows the programmer to supply their own equality test.

> nub [1,2,3,4,3,2,1,2,4,3,5]
[1,2,3,4,5]

Goal

If you ever golfed in Haskell and you kind of needed to deduplicate a list, chances are that you chose a different route or were annoyed that there seems to be no solution shorter than importing Data.List.

In this challenge you will write a function [a] -> [a] (unnamed or named) which removes duplicates from a list, the order does not have to be preserved.

Scoring

Since I don't think it's possible to get something shorter than 20 bytes and Haskell sometimes is really annoying to golf with if you want to use lengthy functions, the scoring mechanism will count tokens, please use this program to count the tokens and use the generated template.

• If your solution is a named function or operator, it must not be defined in another file/module (ie. banning imports).

• Each solution may impose type constraints, each set of type constraints counts as its own language, compiler flags can be used without any restrictions.

• Your solution may not assume that the input is non-empty, however if you have an elegant solution which fails on empty input, feel free to include it in your post.

How are tokens counted?

Tokens are counted by using GHC's lexer which you can import Language.Haskell.Extes.Lexer, except that newlines will count as a token too.

White space is ignored, every token of the language will count as one, no matter how long it is so ma >>= f will count as the three tokens ma, >>= and f the same holds true for string or number literals (eg. "abc" or 1.0 each count as 1).

Test cases

[] -> []
[1] -> [1]
[1,1,1] -> [1]
[3,1,1,2] -> [1,2,3]
[1,2,3,3,2,1] -> [1,2,3]

Answer 28

Make a markdown Table of contents parser

A simple Code Golf challenge in the likes of the Markdown parser.

The parser should ignore normal text and other markup (without an # before it).

Some valid headers are: ### Header 3, # Header1, Text # Header

Sample input:

# Hello
Lorem # Hello2
Hi this is normal text

## This is a subheader
Lorem ipsum

### Subsub
Solor di amet

# Hello again
This is more text!

sample output:

Hello
Hello2
- This is a subheader
--- Subsub
Hello again

Answer 29

Growth of the Jackpot (Tentative Name)

(Gauging interest)

king-of-the-hill game

---

There is a money pot that gains $1 for every player currently in the game each turn. At any time, a player can decide to take the money and run or stay in the game hoping for a larger pot. If more than one player decides to leave at the same time, the money will be divided evenly among them, rounded down, with the remainder being put back in the pot. If after 100 rounds, there are still players left in the game, they will split whatever is in the pot at that time. Whoever has the most money at the end of the game wins.

Write a bot to play this game. You will always know the size of the pot, how many players are currently playing, how many were initially in the game, and the current first place amount of money.

---

On the surface, the optimal strategy is to bail out on turn \$\lceil{100n \over {2n - 1}}\rceil\$ (where \$n\$ is the number of players) because that turn guarantees that nobody can do better than you. But then if everyone does that, they'll split the pot and lose, so the best action to take is not immediately obvious.

---

One possible variant to round limits would be to have it cost each player $1 per turn they stay in the game, with each player starting with $100 and being forced to take the money and run when they have none left to contribute. Then the game could be run for several rounds.

Answer 30

Hungry Monster 9

My first challenge. Feedback is appreciated.

A monster shaped like 2 is hungry and wants to become a 9. To do so he will eat food, that is shaped like the number 1, seven times.

0000000000
0000100000
0100000000
0000001000
0000020000
0100000000
0000000100
0010000000
0000001000
0000000000

Challenge

It starts with a grid filled with 0, containing the digit 2, and seven times the digit 1. The 2 (aka the monster) needs to move to the closest 1. Upon "eating" the number, 2 will change to 3, and continue to move to the next closest number.

Write a program that outputs the next correct state.

Input specifications

• The input grid is a rectangle and can be of any size. It doesn't need to be a square.
• The input can be at any state. For example a grid with a 6 and three times 1 left.
• The grid will contain exactly one digit higher than or equal to 2 (the "player").
• The grid will contain seven times or less the number 1.

Rules

• When the monster gets on the position of where a 1 is, its digit increases by 1.
• The monsters previous position becomes 0.
• When the monster is 9, it does not move.
• The monster can move in 8 directions (horizontally, vertically, diagonally).
• The monster moves to the closest 1. If there are multiple closest, you may choose any of those. It is not required to be random.

Example Input and Output

This is an example of the first 4 states (and example inputs/outputs):

0000000000
0000100000
0100000000
0000001000
0000020000
0100000000
0000000100
0010000000
0000001000
0000000000

0000000000
0000100000
0100000000
0000003000
0000000000
0100000000
0000000100
0010000000
0000001000
0000000000

0000000000
0000100000
0100030000
0000000000
0000000000
0100000000
0000000100
0010000000
0000001000
0000000000

0000000000
0000400000
0100000000
0000000000
0000000000
0100000000
0000000100
0010000000
0000001000
0000000000

The output is allowed to be an array of lines. ["0000000000", "0100000000", "0000080000"]