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

Combinatorial Pipes

math combinations

You're a plumber working on a house, and there's some pipes that must be connected at odd angles. You have 8°, 11.25°, 22.5°, 45°, and 90° fittings at your disposal, and you want to use as few as possible to match the angle as closely as possible.

Goal

• Match the desired angle as closely as possible, with as few fittings as possible. It can be over or under the desired angle.
• Accuracy is more important than the number of fittings
• In the case of two different sets of fittings with the same resulting angle, whichever has the fewest number of fittings should be selected.
• If the two sets use different fittings, match the same angle, and have the same number of fittings, either may be chosen.

Input

Your input is a random integer between (non-inclusive) 0 and 180, which represents the desired angle.

Output

Your output should be an array where [0]-># of 8° fittings, [1]-># of 11.25° fittings, etc. If your language does not support arrays, you may output a comma separated list, where the first value represents the number of 8° fittings, and so on and so forth.

Test Cases

90° ->[0,0,0,0,1]
24°-> [3,0,0,0,0] ([0,0,1,0,0] uses less fittings, but is less accurate and therefore incorrect)
140°->[2,1,2,0,1]
140°->"2,1,2,0,1" acceptable if language does not support arrays

Scoring

Lowest byte count for each language wins a high five from me if we ever bump into each other (and the challenge).

Sandbox Questions

Howdy! I feel like this could be an interesting golf, but I'm unsure if the language is clear and concise enough to get the idea across.

Answer 2

Decode USB packets code-golf binary coding-theory encoding

Posted

Answer 3

Answer 4

Remove All Comments From Smalltalk for Code Golf

code-golfstring

Duplicate?

Edge cases?

Not interesting/challenging?

Tags?

Answer 5

Determine Centrosymmetric String

code-golf, string, decision-problem

Let's define a centrosymmetric string as follows:

• First, add spaces to the end of each line to make the input a rectangle \$ A_{m×n} \$.
• The input is "centrosymmetric" string if and only if you get the original rectangle if you rotate the rectangle 180°. That is, it has 2-fold rotational symmetry, so \$ A_{i,j}=A_{m+1-i,n+1-j} \$ holds for all \$ A_{1\dots m, 1\dots n} \$.

Input

Input a non-empty string. You may assume it:

• does not contain leading / trailing new lines;
• does not contain trailing spaces on any lines;
• only contains new line, space, and lowercase a-z.

You may choose to handle any of CR, LF, or CR-LF as the new line character in your program.

Input may be in any reasonable format, including but not limited to:

• A built-in string type;
• A NULL-terminated character array;
• An array of integer code-points;

Note that you are not allowed to take the string padded already as it trivialises the challenge.

Output

Determine if the given input is a centrosymmetric string (as defined in this post), outputting two distinct values, or truthy vs. falsey values (they can be swapped relative to their normal meaning).

Test cases

Truthy

a

aba

a
b
a

ab
ba

abc
cba

abc
ded
cba

a a

a

a

a

 a

a c
 b
c a

a

 b
 b

  a

zzzzz
   z
  z
 z
zzzzz

n  n  oo   oo  n  n
nn n o  o o  o nn n
n nn o  o o  o n nn
n  n  oo   oo  n  n

Falsy

ab

a
a
b

a
 b
a

ab
ab

aa
bb

   a
  a a
 aaaaa
a     a

Answer 6

Is there a left-right connection?

code-golf path-finding binary-matrix decision-problem

Task

Given a square array of 0s and 1s, determine whether or not there exists a path of 1s connecting the leftmost and rightmost columns. A path can take steps of one unit up, down, left or right, but not diagonally. Every symbol on the path must be a 1, and it must start somewhere in the first column and end somewhere in the last column.

Shortest code in each language wins.

Examples

000
111   ->  True
111

110
110   ->  False
110

101
010   ->  False
101

0     ->  False

1     ->  True

11110
00010
01110 ->  True
01000
01111

11110
00010
01100 ->  False
01000
01111

Notes

The array may be represented in any reasonable form, such as a list of lists [[0,0,0],[1,1,1],[1,1,1]] or a string '000 111 111'. It can optionally be in transposed form (so that the roles of rows and columns are exchanged; equivalently the code can instead determine whether there is a top-bottom connection). Any two distinct symbols can be used in place of 0 and 1. The output can be in any truthy/falsy form.

Answer 7

Consecutive Distance Rating code-golf array-manipulation integer

Posted

Answer 8

Title: Make a WebCrawler dictionary writer.

Notice: for any text within <> tags, please ignore any .'s. These are simply added so that they are treated as plain text, and not code.

Your goal is to make a program that acts as a regular WebCrawler, but also writes a dictionary using the websites.

You should have a list that is used to store words that have been added called Dictionary, and another list to store website urls called NextSites. You should also have a variable called sites, and a variable called input2. Any other variables or lists are optional.

It should ask for input upon running the program, allowing you to input a website url, from where it will start web crawling. How it asks for input does not matter, so long as you are able to use any website as input. It should then ask for input again, allowing you to chose how many sites it should continue for. The variable much should be set to this input.

Next, it should check the website for any text contained within <.p> tags. It should separate the text contained within the tag at any space contained in it. Next, it will compare each part that has been separated against the current text in the list used to store words. Any part that is not already in the list should be added to it.

After it has checked all of the text within the <.p> tags on the site, it should check for any <.a> tags on the site. Any urls that it finds in the 'href' part of the <.a> tag should be added to the website url list, so long as the url list is not larger than 99 urls. (This means that the maximum amount of urls that can be in the url list at any one time is 100).

When all of the <.a> tags on the site have been checked for urls, it should change the current site it is on to the first site in the list of urls. It should remove this url from the list, and move all other urls to the spot one less than them on the list, so that there is no empty space at the beginning. (eg: If you had 3 urls: 1. google.com , 2. wikipedia.com , 3.stackexchange.com, then after switching to google.com, the list would now be 1. wikipedia.com , 2.stackexchange.com .)

It should then repeat the above steps, and continue to do so until the variables sites and much are the same.

Next, it should should output the entire list of words that it found. The method used to output it does not matter, so long as all words in the list are outputted, with a new line for each word. E.g.: You may have found the words cat, mouse, and food. The output would look as follows:

cat

mouse

food

Scoring: The scoring follows regular code golf rules. The person with the smallest program in bytes wins. However, in the case of a tie between two programs, the program that can webcrawl and write the dictionary starting on wikipedia.com for 100 sites fastest will win.

Answer 9

Largest Number with No Repeating Digit Pairs

Inspired by the problem with the same name on Puzzling SE.

You are to find the largest number that only uses every digit pair once, in a given base. For example, in ternary we have 2212011002. We can do this greedily by simply starting with the largest number, and then adding the next largest number we can without repeating a pair, until we’ve gotten them all.

Challenge: Given a base from 1-10, output the largest number in that base with no repeating digit pairs.

As long as the digits make the number, you may output with anything, or nothing, in between. Whether regularly delimited, or irregularly gibberished.

You may also take input in any reasonable way. For example, you might take the base, the max digit, or an ordered list representing the digits available. For octal, this would mean 8, 7 or 76543210. If you feel like a challenge, you can take octal as input. I won't complain!

Note that it need only work for bases from 1-10. Invisible points for doing alphanumeric bases like hex, but not at all required.

This is code-golf, so least bytes per language wins.

Test Cases

Decimal: 10
99897969594939291908878685848382818077675747372717066564636261605545352515044342414033231302212011009


Octal: 8
77675747372717066564636261605545352515044342414033231302212011007


Quaternary: 4
33231302212011003


Ternary: 3
2212011002


Binary: 2
11001


Unary: 1
00

Answer 10

Draw an Ascii Grid

Answer 11

Implement a cleave function

functional-programming code-golf

Answer 12

On a Collapsing Platform

Rules

In this KoTH, your task is to not die. It seems simple, right? Well, no.

You're on a platform. A giant platform, of size 100 * (entries) ^ 1.1 units across (this may change if we get a lot of entries). And every few turns, a random tile is removed. As well as this, you, not a small mass in the scale of things, can cause a tile to fall down. Let me explain how this works.

You (the entrant to this KoTH) control a certain number of bots. You (the bots) can then move around on the platform and try not to die. You (still the bots) can move up to 10 units away at base, and can see up to 100 units away (units will be called u from now). However, jumping over a hole costs 2u more, meaning that the largest gap you can clear is three units (3 * 3 for the gap and 1 to land). Do not try and clear 4u+ gaps; you will die. Going off the edge of the platform also is an unwise choice - you will die.

By "you - not a small mass in the scale of things", I mean to say that every step you take takes you closer to your inevitable death - each tile you step on has a hidden durability stat, that will not be revealed to you during the course of the round. When it hits 0, the unlucky bot (hopefully not you (the bot)) on it will be removed with the tile. Do not do this; you will die.

Your weight is a random stat that is decided at the start of your game, and is subtracted from a tile's durability each time you step on it (weights are 150 at base, and durability values in the range of 15000 - 45000 * (entrants) ^ 1/2, or 15000 * 1-3 * entrants ^ 1/2, so it only becomes an issue in the long term, or when a lot of players exist.) Do not forget about this and start camping on the same 10 tiles on the end; you will die.

Everything takes place on a tick system - every 10 ticks, you can do an action (subject to change to 20ish if this is exploitable) and this may well be the most important part of the game - reduce it at all costs - the fewer ticks you waste, the less durability you take off, and the longer you can thread the needle between life and death. Do NOT, and I mean NOT in caps, forget about this - you will die.

There are a few items that you can get that will improve your chances and delay your inevitable death represented by these characters:

-: Removes 1-7% of your weight (or 1-7, whichever is lesser)

=: Increases your speed by 1 (at 13, this will in fact, prove me wrong and let you clear 4u jumps - still not got the + though).

? Increases vision by 5 (allowing you to see 5 more blocks in either direction.

> Reduces your tick delay by 0.1 or 1% of your tick rate, should it drop below 5 (however, before that, you will die most likely.)

+ Duplicates the bot - you start with 10 bots, and each bot left over at the end is worth 10 000 points (1 per tick survived), so this can, effectively, give you 10 000 points free.

Every 10-25 turns, a random platform is removed - unless necessary, this will not drop any bots - the platform chosen will always be empty (just so people don't get unlucky and die at turn 85) unless it is forced not to be - for example, in the endgame, where there is only 10 tiles left. Do not forget this; you will die

Input and Output

To begin with, you will get a string such as this

0, 111, 132, 122, 133, 211, 201, 212, 233, 310, 323, where:

The first number represents your unique player id, known as PID in the it gang. Then, you get 10 numbers, representing your bots' start positions.

Then, for each turn, for each bot that did not die, you (the player) get a string such as this (shortened to save space):

.___.+>-__u__...+>+-_._

representing the bot's vision.

You must then return an integer, representing how many units you wish to move forward (negative is backwards) (and do not forget that spaces take 2u more, or you will die.); do not try and move more than your speed, or it will be modulo-ed. Errors and invalid input return 0. Note, spaces are represented with ., in the examples and in game.

Helper functions (to delay your death, hopefully until the end):

info(): gives you a chunk of info, in this format:

PID: 0
Bots: 11
Score: 10000
[
BID: 1
Weight: 97
Speed: 12
Tick Delay: 8.8
Vision: 110
Pos: -932
Score: 830
]

[
BID: 3
...
]

The string is format as such:

• First, your unique PID.

• Then, the number of bots you still have.

• Then, your total score.

• Then, for each bot:

  • Its bot ID (or BID for the it gang). (Note, BID are cannot be reassigned, so if Bot 2 dies, and then Bot 1 duplicates, it will have a BID of 10, not 2 (also we count from 0) as it would be if they were.)

  • Its weight, speed, tick delay and vision, in that order.

  • Its position on the platform, in that order.

  • Its score.

position(): gives a position of every bot, ordered by their bot ID, or BID (again, only for the it gang).

position(ID): gives the x position for a bot with a specific ID. If that ID has died already, it will return "Dead" - plus the space where it died. If that bot never existed, it will return None.

tickdelay(), weight(), speed(), vision(), tickdelay(ID), weight(ID), speed(ID), vision(ID):

Does exactly what it says on the tin, returns that specific stat for all bots if no ID is given, or the one with that ID should it be given (again, if the bot is dead, it just returns its stats on the turn it died, and if it never existed, it returns None. Make of it what you will).

vision(ID) Gives a specific bot's vision - this is useful for sketching a map of the world in conjunction with position(ID). Note that other bots are represented as s, so if you're lucky enough to get your bot (u) in between two opposing bots (s), feel free to laugh.

You are allowed access to ALL the random functions (apart from random.seed(), however I will use a set of predetermined seeds in a random order to facilitate retesting. There will be a large number of trials done - this is just to aid improvements if you so desire to make them.

Bots can store variables and write to files, but ONLY in their directory. I will find any bot who does this and ban them.

Scoring

Bots gain 1 point for each turn they survive, increasing by 1 every 100-200 turns. This will be notified with the string Score/turn increased by 1. Every powerup gives +500, except for +, which duplicates the bot, including its score, thus adding its score to your total. At the end, when there is three or fewer tiles left, you gain 10000 + the bot's current score for each bot left alive. This is done for every bot that lives, so people getting 2 or more bots through gain more than those getting 1, and two opposing bots can both get points for their team.

At least 10000 games will be run per round (subject to change), each time resetting all the stats to the base, rerolling RNG and restarting from the beginning.

After as many rounds as I can get through on my PC, the scores will be added up, and the winner gets an accept.

Meta

Help with a Python controller would be appreciated.

Any specifications need to be made?

Should I edit any formulae?

Answer 13

When's my weekend finally here?

Answer 14

Reverse RegEx

Take a regex a as input, output a regex b such that, for each string x, x matches a iff x.reverse matches b.

Here, regex need to support such symbols:

• .(any character expect \n)
• [abc](any character in abc)
• [^abc](any character not in abc)
• x?(appears 0-1 times), x*(appears any amount of times), x+(appears any positive amount of times)
• x{n,m}(appears n to m times, m can be omitted to mean infinite)
• (abc) (?:abc)(group block, () can be referred while (?:) can't)
• \n(refer to the latest match of n-th group)
• ^(begin of string), $(end of string) (or begin/end of line, see flags/m)
• |(or, choose one in some choices)
• Letters, \n(this n is char rather than variable, line-feed)

You need to handle flags i(ignore upper/lower case) and m(multiline, ^ and $ match begin/end of lines rather than string). You can also just pipe the flags and make the containment of regex work for all possible flags, aka. you can treat pipe free. (They refuse to allow or disallow)

Sample Input    Sample Output
/abcd/          /dcba/
/[abc]/         /a|c|b/
/[^abc]/        /[^abc]/
/(.)abc\1$/     /^(.)cba\1/
/$1/            /10% of $10/

Shortest code win

Answer 15

The Great Betting Game

Answer 16

Play Thud

Thud is a game described by Terry Pratchett in his novel, Thud!.

The game simulates a battle between the Dwarfs (in blue) and the Trolls (in green) on an octagonal board with the Thudstone (an impassable space) in the centre of the board.

I have created an environment to play the game and develop game playing code at: https://ajfaraday.github.io/Thud/dist/index.html

The challenge is to write the most successful dwarf or troll player of this game (these will be two separate challenges).

Rules

Starting with the Dwarfs, players take it in turns to move.

Dwarf Movement

On the Dwarf player's turn, they can move one dwarf piece either as a walk or a hurl.

Walk: Dwarfs can move as far as they like in any direction until they hit an obstacle (another dwarf, the edge of the board, or a troll). They can only kill a troll by walking if they are only one space away.

Hurl: If two or more dwarfs are in a line (horizontal, vertical or diagonal), they can hurl the dwarf on the end of the line, by the length of the line (e.g. in a line of 3, the dwarf on the end can be hurled 3 spaces). If a dwarf is hurled into a troll, the troll is killed, reducing the trolls score by 4 points.

Troll Movement

On the Troll player's turn they can move one troll piece, either as a walk or a shove.

Walk: Trolls can move one space in any direction, unless a troll, dwarf or the edge of the board is in the way. Whenever a troll moves, it kills all dwarfs adjacent to it's destination space.

Shove: If two or more trolls are in a line (horizontal, vertical or diagonal) they can shove the troll at the end of the line that number of spaces away, but only if any of the target space's immediate
neighbours contain a dwarf. When a troll is shoved, it kills all dwarfs on or adjacent to it's destination space.

It is not permitted for a troll to land directly on a dwarf by either walk or shove moves.

Each dwarf killed reduces the dwarfs score by 1 point.

Scores

The score is calculated thus:

• The dwarf player has one point for every dwarf remaining on the board.
• The troll player has four points for every troll remaining on the board.
• The key figure is the difference between these two. This will be used to calculate players' scores in the tournament.

Ending the game

The game ends when any of these conditions is met:

• There are no dwarfs on the board.
• There are no trolls on the board.
• Both players have declared the game over.
• The game has reached it's cut-off length of 500 moves.

How to manually play a game

• Go to https://ajfaraday.github.io/Thud/dist/index.html
• Hover the mouse over a piece to see it's available moves.
• • Safe moves are outlined in green.
• • Dangerous moves (which can be killed the next turn) are outlined in orange.
• • Killing moves are highlighted in red when the mouse hovers over them.
• Click a piece to select it for the current move.
• Click one of the available moves to move the piece.
• (You can click the relevant 'Make Peace' button to declare the game over according to that player, during their turn)

How to set up a local instance of the game

You don't have to clone the repository and use it locally to to create an entry, but it helps.

• git clone [email protected]:AJFaraday/Thud.git
• cd Thud
• npm install
• You can then run ./get_answers.sh to get the latest entries from Stack Exchange

If you prefer, you can use the github pages instance at https://ajfaraday.github.io/Thud/dist/index.html

How to customize a game

• Open /dist/index.html in your browser
• Click 'Customize'
• Select troll and dwarf clients (manual allows direct control)
• Select a turn time in milliseconds (only relevant to non-manual players)
• Click 'Run Game' to see or play the game.
• (Clicking 'Close' will not enact any changes)

Clients

The game is played by clients, which represent either a troll or a dwarf player. Each is a JavaScript class which must have these three functions:

• constructor(controller) - controller is an object which acts as your interface with the game (see below).
• turn() - This is called whenever it is your players turn to move.
• end_turn() - This is called after your player's turn is over. It can not move pieces, but can make decisions on whether or not to declare the game over.

Controller

The controller object is your client's interface with the game itself. You can find full documentation for the controller class here: https://github.com/AJFaraday/Thud/blob/main/docs/controller_interface.md

It provides these methods to interrogate the state of the game:

• turn() - Current turn of the game

• scores() - The current score

• spaces() - Every space, and what's in it

• space_info(x, y) - Detailed information on any space on the board.

• dwarves() - The location of every dwarf

• trolls() - The location of every troll

• pieces() - All pieces belonging to the current player (equivalent of dwarves() or trolls())

• indexed_dwarves() - The location of every dwarf with a fixed index

• indexed_trolls() - The location of every troll with a fixed index

• previous_move() - What got moved to where last turn

• killing_moves() - All moves which can kill one or more opponent

• current_space - Currently selected space (not a function)

• clear_space() - Empties currently selected space These methods are used to actually make your move:

• check_space(x, y)- Find out what moves are available from a given space

• select_space(x, y) - The player decides to move a piece at space.

• check_move(x, y) - Find out what will happen if you move to a place

• move(x, y) - The player moves the current piece to the selected space.

These are concerned with ending the game:

• declare(game_over) - Say whether or not your player thinks the game is over.
• opponent_declared() - Has the opponent declared the game over?

How to write a client

Warning: There is an issue with the project on Firefox (https://github.com/AJFaraday/Thud/issues/3) which prevents editing the code in the browser. This has been confirmed to work in Chrome.

• Open 'dist/index.html' in your browser.
• Click 'Customize'.
• Select 'dwarf/template' as the Dwarf player (or use another client as a starting point).
• Click 'Edit' beside the Dwarf player select.
• Write your client code in the text box provided.
• The Validate button will change colour based on whether or not the client is passes validations (see below).
• When you're happy with it, click 'Apply' (This can be done before it passes validation, but it may not actually work).
• Select a worthy opponent and click 'Run Game' to see the game.

Validations

In order for a client to work, and therefore be enterable in the challenge, it has to pass these validations:

• It must evaluate as Javascript code.
• The code must return a class, with a constructor which accepts one argument.
• Instances of this class should have functions named turn() and end_turn()
• The client must play a game until it is over (i.e. it must call a valid move during every turn call). The validator will run games against default opponents to determine if this happens.
• Does not have any forbidden terms ** game. - Only interact with the game via controller ** Math.random - Please keep it deterministic ** setTimeout or setInterval - Keep it sequential
  ** eval, require or import - Just don't

You can open the developer console (F12) to see more detailed information on your client's validation process.

How to save a client

If you have cloned the git repository, you can save your entry for future tinkering. This step is not required for entry in the challenge, but it may be helpful.

• Edit a client, as above.
• When you're happy with it (preferably if it's passing validation, too), click 'Copy' from the edit interface.
• Create a .js file in /src/clients/dwarf/entry with the name of your entry e.g. /src/clients/dwarf/entrygreat_dwarf_player.js. (This folder will not be wiped by get_clients.js)
• Run node script/get_clients.js from the Thud directory to make your entry available from the Dwarf player select. You only need to do this once to make it avilable.
• npm run build - this will keep watching for changes in your entry and updating the package.

How to enter your client in the competition

• Decide on the name of your client, your client_name must only have alpha characters and underscores.
• Answer this question with your entry
  • The first line of your answer should be your client's name as a title (with = characters under it on the second line)
  • There should be a code block containing the class for your entry (with or without the preceeding module.exports =)
  • After that please include a brief explanation of your client's behaviour, and any other information you'd like to include.

Once this is in place, anyone running ./get_answers.sh will see your client available under your username.

The GitHub Pages instance will also be updated periodically. So by making an entry, your code will be added to the repo.

Tournament rules

The tournament will pit every available dwarf client (in /src/clients/dwarf/) against every available troll client (in /src/clients/troll/), and each pairing will play exactly one game.

The difference between the two players' scores will then update a running total for each client. The winner will gain the difference, and the loser will lose the difference.

There are two winners in the tournament, the most successful troll player and the most successful dwarf player.

According to the rules, after playing a game, the players swap sides, so please also write an entry on the Troll challenge.

asymmetrical king-of-the-hill game board-game javasctript

---

This is now nearly complete (apart from some UI improvments and presenting the tournament results a bit more nicely). There's a working example of the code importer working against these two meta questions:

• Dwarf: Stack Exchange API Sandbox (dwarf edition)
• Troll: Stack Exchange API Sandbox

I could really use someone to attempt an end-to-end run at creating a client and adding it to one of these to check that my instructions are clear and everything works.

Answer 17

Print this sequence I just made up

Answer 18

Generate off-by-one regex for a string

Given an alphanumeric string as input, generate JS-flavored regex in order to match any off-by-one errors for that string. In stricter terms, your resulting regex must match any single deletions, single replacements, or single additions like in the below examples.

Examples:

"hi" -> "(h|i|.i|h.|.hi|h.i|hi.)"
"golf" -> "(olf|glf|gof|gol|.olf|g.lf|go.f|gol.|.golf|g.olf|go.lf|gol.f|golf.)"

Here is a program for generating the results.

Note: The order of the regex does not need to matter (ie, "hi" could be "(h|h.|hi.| . . .")) so long as all patterns are in the regex.

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

code-golf code-generation regular-expression

Answer 19

Are you a probabilist or a physicist?

Answer 20

Calculate the integer square root of a matrix

Answer 21

Pinpoint the typo!

Task

Write a program that finds the location of an error in its own code!

The program itself must output either nothing or an empty string (or an appropriate equivalent in your language).

Let n be the length of the program in bytes, which must be at least 2. For an integer k with 1<=k<=n, if the kth byte of the source code is deleted, then the resulting program should output the integer k (and nothing else), in as many cases as possible.

Outputs may be 0-indexed if preferred, so that omitting the kth byte outputs k-1, but the choice of indexing must be consistent across all k.

Error messages do not count as valid output unless they are of exactly the required form.

Your score is the number of integers k for which the above condition is satisfied, divided by n. Highest score wins, with ties broken by smallest n.

Example

Consider the program blob() in a fictitious language. Suppose that:

blob() outputs nothing (this is a requirement)

lob() outputs 1 (right)

bob() outputs 2 (right)

blb() outputs 3 (right)

blo() outputs 4 (right)

blob) outputs nothing (wrong)

blob( outputs 6: Syntax error (wrong)

Then the score would be 4/6 = 0.66666667

Answer 22

IATA Airport Codes code-golfdecision-problemstringkolmogorov-complexitycompression

Out of 17576 alphabetical triplets, to this day, 9144 are used as IATA airport codes.

Given a 3-letter string, tell whether it appears in the list.

• The input string is mixed-case by default, but you can restrict it to non-mixed-case or lower-case or upper-case

• To output the affirmative/negative outcome you should use:

  • truthy/falsy according to your language's convention (swapping is allowed), or
  • one consistent value as either affirmative or negative, and any other value as the other

• This is code-golf

_{The list was scraped from iata.org on 2021-08-07}

Meta

• Is there something that needs to be specified/clarified?

Answer 23

Sum of 3 Vectors

code-golfnumber-theory

Question

Given 3 vectors a, b, c

Find integer (n, m, r) where a*n+b*m+c*r = 0 and n,m,r are all not equal to 0.

your answer group (n, m, r) must be the closest valid group to 0, calculate by adding abs value together: |n|+|m|+|r|

You can assume that 3 vectors do not parallel

Test case

work in progress

Rules

• no Standard loopholes
• any I/O case allowed, as long as it's clear and mostly understandable.

Score

• Lowest byte count per language wins!

Meta

any extra tag?

suggestions?

Rename question?

Answer 24

Distances between keys on a QWERTY keyboard

Answer 25

Answer 26

Unfudge my terminal!

Intro

Today I fiddled around with termios for a program. The only thing I managed to do so far is fundging my terminal... can you help me out?

Challenge

Given a terminal input that contains fudged special chars, output the string that should be displayed if the terminal worked correctly. Here's a list of the broken special chars:

^B -> Backspace
^J -> (Fwd-) Delete
^W -> Discard
^D -> Cursor left
^C -> Cursor right
^F -> End
^H -> Start

How the special characters work

• Backspace deletes the character behind the cursor and moves it one step back. Has no effect on the start of the string.
• Delete deletes the character in front of the cursor. Has no effect on the end of the string.
• Discard deletes the string typed up to this point.
• Cursor left/right moves the cursor to the left/right by one. Has no effect on the end/start of the string.
• End/Start move the cursor to the end/start of the string.

Undefined special characters are to be removed.

Input

• Any represetation of a string/list of characters
• Single lines only
• The special characters may be either all capitalized or all not capitalized
• The input will not contain a sequence that will result in a ^ in the output, nor will it contain a single ^ at the end.

Output

• The unfudged input.
• No leading/trailing whitespace that isn't part of the string.

Examples

abcd^B^B^B --> a

abcd^We^Af^Lgh --> efgh

 gof^D^D^D^Dcode^C^C^Cl --> code golf

ocde gol^H^J^Jco^Ff --> code golf

edgecase^H^D^B^J^F^C^J^B --> dgecas

Rules

• This is code-golf, shortest answer wins
• Standard loopholes are not allowed
• A submissiom may be a program/function/link/lambda/chain/etc.

Tags: code-golfstring

Sandbox things

• Is anything unclear?
• Should any special char be added or removed?
• Is there an edge case not covered by the examples?
• Are the rules and I/O restrictions fine or should I change anything?

Answer 27

Snap (card game)

Answer 28

Display a number in Toki Pona

Answer 29

Khinchin's constant bad estimate

Answer 30

Unicode Calendar Generator

Rules

Your program will receive a valid date in the format relevant to your language (date object or three int for year, month, day or whatever) and should returns a fancy unicode calendar as such (note that the title is right/left aligned):

Given Y-M-D as 2021-10-13
Then

╔════════════════════╗
║ October ░░░░░ 2021 ║
╟──┬──┬──┬──┬──┬──┬──╢
║░░│░░│░░│░░│░░│01│02║
╟──┼──┼──┼──┼──┼──┼──╢
║03│04│05│06│07│08│09║
╟──┼──┼──╔══╗──┼──┼──╢
║10│11│12║13║14│15│16║
╟──┼──┼──╚══╝──┼──┼──╢
║17│18│19│20│21│22│23║
╟──┼──┼──┼──┼──┼──┼──╢
║24│25│26│27│28│29│30║
╟──┼──┼──┼──┼──┼──┼──╢
║31│░░│░░│░░│░░│░░│░░║
╚══╧══╧══╧══╧══╧══╧══╝

Given Y-M-D as 2021-11-13
Then

╔════════════════════╗
║ November ░░░░ 2021 ║
╟──┬──┬──┬──┬──┬──┬──╢
║░░│01│02│03│04│05│06║
╟──┼──┼──┼──┼──┼──╔══╗
║07│08│09│10│11│12║13║
╟──┼──┼──┼──┼──┼──╚══╝
║14│15│16│17│18│19│20║
╟──┼──┼──┼──┼──┼──┼──╢
║21│22│23│24│25│26│27║
╟──┼──┼──┼──┼──┼──┼──╢
║28│29│30│░░│░░│░░│░░║
╚══╧══╧══╧══╧══╧══╧══╝

Given Y-M-D as 2021-06-15
Then

╔════════════════════╗
║ June ░░░░░░░░ 2021 ║
╟──┬──┬──┬──┬──┬──┬──╢
║░░│░░│01│02│03│04│05║
╟──┼──┼──┼──┼──┼──┼──╢
║06│07│08│09│10│11│12║
╟──┼──╔══╗──┼──┼──┼──╢
║13│14║15║16│17│18│19║
╟──┼──╚══╝──┼──┼──┼──╢
║20│21│22│23│24│25│26║
╟──┼──┼──┼──┼──┼──┼──╢
║27│28│29│30│░░│░░│░░║
╚══╧══╧══╧══╧══╧══╧══╝

This is code-golf, so you the shortest bytes of each language will be the winner.

Inspired by qwerty.dev