Sandbox for Proposed Challenges

Question

What is the Sandbox?

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

To post to the Sandbox, scroll to the bottom of this page or click on the "Add Proposal" link below, and click "Answer This Question". Click "OK" when it asks if you really want to add another answer. Write your challenge just as you would when actually posting it. You may also add some notes about specific things you would like to clarify before posting it. Other users will help you improve your challenge by rating and discussing it. When you think your challenge is ready for the public, go ahead and post it, replace the post here with a link to the challenge and delete it.

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

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

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

Answer 1

Maximize the velocity of a group of cars

---

A group of cars are in the right lane of a straight two lane highway. Each car has a preferred speed. In order to reach this preferred speed, some of the cars need to change lanes, perhaps multiple times.

All cars are exactly 1 meter long. At the start of the simulation, there is zero space between each car and the car in front of it. Acceleration is instant. Cars move at their preferred speed whenever possible. If a car would bump into another car, instead it immediately decelerates to match the speed of the car in front.

Give the starting order and preferred speed of each car, your task is to find some combination of lane changes such that all cars reach their preferred speed, and could continue to do so forever without any further lane changes, in the smallest amount of time.

Input

Two lists are given as input:

• A list of strings that represent car names
• A list of integers that represent preferred speeds, in meters per second

The order of the car names indicates the starting order, with the first car in the list begins at the front of the pack. You can map cars to speeds using position in the list.

Output

You will output a list of lane change events that, if followed, leads to a situation where all cars are currently driving at their preferred speeds, and could continue to do so forever. The solution must also be the fastest such solution in terms of simulation time. Another way to say this is that the timestamp of the last lane change event must be minimal.

Each event must include a timestamp and a car name. The timestamp must be the number of seconds since the beginning of the simulation, rounded to the nearest hundredth of a second.

---

code-golf

Answer 2

Decide if an integer is uniform

I was recently implementing a Local Binary Patch (LBP) descriptor, and found the need to decide if a number is uniform, as described below. You can read about why this is needed in object detection here.

Input/Rules:

1. Take a (signed!) integer n in any way that seems reasonable to your language of choice.
2. The number will be given as a decimal.
3. Your approach must work with at least all 32 bit encoded integers, including 0. This means from −2,147,483,648 to 2,147,483,647, i.e. from −(2^31) to 2^31 − 1
4. Negative numbers must be turned to binary with Two's-complement. (With One's complement the output is the same as for the unsigned version of the number every time).
5. Only the minimal number of bits required to encode the given number matters.

Output:

A truthy/falsey value if the number is uniform.

Uniformity:

An integer n is considered to be uniform, if the number of transitions from 1 to 0 or from 0 to 1 in the binary encoding of n ist less equal to 2.

Examples:

Given the number 12, its binary encoding is 1100. There is 1 transition here:

1100 |

Thus, your output should be truthy.

Given the number 10, its binary encoding is 1010. There are 3 transitions in here:

1010 |||

Thus, your output should be falsey.

Given the number -12, its binary two's complement encoding is 0100. There are 2 transition here:

0100 ||

Thus, your output should be truthy.

Here is an example for which the two's complement matters: Given the number -125, its binary two's complement encoding is 10000011. There are 2 transitions here:

10000011 | |

Thus, your output should be truthy.

Side note: If we did the same with one's complement, the encoding of -125 would be 10000010, which has 3 transitions.

Shortest code in bytes wins.

Sandbox notes:

This is my first code golf question, feel free to yell at me. Tags: code-golf sand-box numbers decision-problem

Answer 3

Make a shuffle quine!

_{Closely based off this sandbox post, however I deleted the old one and posted this new answer for new feedback.}

code-challengequineanagram

An shuffle quine is defined as a quine, of which shuffled sets of "chunks" also form quines.

For example, pretend in my magical language the code 123 is a quine.

Let's split this into 3 chunks. 1, 2, and 3. In your answers, these chunks can be any lengths and there can be any number greater than 1 of chunks.

You get a better score for more possible shuffled quines you can make. For example, if 21, 23, 13, 312, and 31 are also quines, in addition to 123, you get (15/6 = 2.5) * <sum of chunk lengths> for your score.

Your score is calculated by the formula sum_of_chunk_lengths * (number of possible shuffled programs/number of quines). In this formula, least score is better.

This is code-golf, so the shortest code wins!

Final notes:

• Each shuffled code is a quine itself, i.e. prints itself not the original program.
• Programs have to be distinct, i.e. you can't count abb and abb as 2 because you swapped the bs.

Sandbox notes:

Yeah, this is really hard. I don't think it's impossible though.

Answer 4

Prisoner's dilemma

Inspired by the "Mafia" proposal

Write a bot that plays the Prisoner's dilemma. King of the hill

Payoff matrix:

Rules:

• Your bot must be a full program, not a function.
• Your bot must run when the server does ./run in it's folder.
• No shenanigans.
• If you want to remember something, save it to a file in your directory.

Input/Output

When the server does ./run:

from_server contains your opponent's last move - Either Cooperate or Defect. On the first round it contains Let's play!

When your program exits (60 sec max):

to_server contains your choice this round. Either Cooperate or Defect. Any other output is interpreted as forfeit; you got 0 points and your opponent gets 5. If both bots forfeit on any turn, nobody gets any points.

Provided bots

There are a few bots that are guaranteed to exist:

• Always defect
• Always cooperate
• 75% cooperate / 25% defect
• 25% cooperate / 75% cooperate
• 50% cooperate / 50% defect

Testing

Your bot will be played against every other bot in a random number of rounds > 100.

Winning

Get the most points after you've played every other bot

Fiddly bits

The game is a file structure something like so:

prisoner/
  -> server.py
  -> yournameherebot/
     -> from_server
     -> to_server
     -> run
     -> *Any other files you want*
  -> someotherbot/
  -> anotherbot/
  -> titfortat/
  -> 50-50_random/

Meta

Please give your CC with your comment instead of a downvote. It's a sandbox for a reason :)

Answer 5

Divide an array into left and right halves.

Input: An array of floating-point values, or whatever is a reasonably large numeric type in your language.

Output: Two arrays. The original array should be the concatenation of the output arrays. The sums of the elements in the two arrays should be as equal as possible.

Examples:

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

Functions or full programs please; no snippets. Normal code-golf rules and restrictions apply.

Answer 6

City Zoner KoTH

You are a city zoner, and your opponent want to zone dirty industrial. You need to stop him. The mayor has set the following rules.

1. A random player is selected to zone the first location. They take turns zoning area. If one player has twice as much area zoned than the other player, that player is skipped (can happen repeatedly)
2. We have a 20x20 square to zone (400 squares total). A player can choose how much they zone, but it must be a rectangle with an area of at least 5. A player cannot zone more than 200 squares total (across the entire game)
3. If the game ends in a tie, the player who played last wins

Your goal is to ensure your opponent zones as few squares as possible.

Answer 7

Store a secret code-golf

Given a password and a secret,

• Serve at localhost:8080.
• If you receive a POST request to / with the parameter p=(...) then check the given password against the fed in password.
  • If it is correct, return a plaintext file with the secret.
  • If it is incorrect, return a 400 error
• Return 400 for any other requests

Rules

• No need to salt and hash the password
• Your server should be able to start in five seconds.
• Your server must be able to server for at least five hours.
• Your server must be able to handle at least 20 connections a second at least in theory. Test script:

---

import requests, random, time
import sys
from string import printable

def gen_string():
    s = ''
    for i in range(random.randint(1, 20)):
        s += random.choice(printable)
    return s

def make_request(str):
    is_child = os.fork()
    if is_child:
        requests.get(str)
        sys.exit()

while True:
    for i in range(20):
        make_request(gen_string())
    time.sleep(0.05)

Answer 8

Exponentiation by squaring

Given an integer x and a non-negative integer n, compute xⁿ using exponentiation by squaring. The key feature of this method is that the time complexity for exponentation can be reduced from Θ(n) using naive exponentiation to Θ(log n) using exponentiation by squaring. There are other names for this method as well as multiple methods which each have an equivalent time complexity. One of them will be explained but feel free to implement the one that is best suited for golfing in your language.

An iterative version is displayed below in Python

def exponentiate(x, n):
    if n == 0:
        return 1
    y = 1
    while n > 1:
        if n % 2 == 0:
            x = x * x
            n = n / 2
        else:
            y = x * y
            x = x * x
            n = (n - 1) / 2
    return x * y

Rules

• This is code-golf so the shortest code wins.
• Your function or program must have a time complexity of Θ(log n). Keep in mind that only time is restricted, not space.
• Your function or program must support all inputs which would not result in integer overflow in your language's integer datatype.
• You are not allowed to use any builtins that perform exponentiation.

Answer 9

Polytope of the pops

In 3 dimensions, there are 5 regular convex polytopes: the platonic solids.

In 2 dimensions, there is an infinity of regular convex polytopes: the triangle, the square, the pentagon, the hexagon, etc…

In 4 dimensions, there are 6 such polytopes, and for 5 dimensions or more, only 3 polytopes - check that cool video for more details.

Challenge

Given as input an integer n>=0, return the number of regular convex polytopes in n-dimensional space, or -1 if the number is infinite.

The sequence (A060296) is (starting with 0 dimensions):

1, 1, -1, 5, 6, 3, 3, 3, 3, 3, 3, 3...

Test cases

0 → 1
1 → 1
2 → -1
3 → 5
4 → 6
5 → 3
2017 → 3

Answer 10

Interpreter chain!

answer-chaining

Create an interpreter for the previous submission! The interpreter could take a string, an array of characters, etc.

Your interpreter must be able to identify each command in the input and interpret the commands.

The first answer must print the integers from 1 to 10.

I/O

(We need this because some languages have trouble with arrays of strings)

To chain the answers, we would need a delimiter to separate the code to interpret and the input of the interpreted code. Thus, you may use any single-character delimiter of your choice to separate the two inputs. Your program must be able to separate the two inputs. Your actual input will always be one string.

What if the previous answer is in Mathematica?

You only need to implement the commands used in the previous submission. That is, if your program/function is run with the previous submission as input, it should become an interpreter for the submission before that. Chaining all the answers would ultimately give integers from 1 to 10.

The commands in the previous answer are too complicated/high-level!

There is no need to implement all aspects of those commands. Your implementation only needs to have identical behavior to the original command when it is used in identical manner to the previous answer.

For instance, if the previous answer is in Brainf*ck, and it uses only 10 cells, you do not need to make an infinite tape; a length-10 array will suffice.

If the previous answer is in Jelly and has a . to put 0.5 in the stack, you do not need to implement the usage of . to form decimal numbers (unless it is used that way).

Note: Commands that are no-op still should be implemented as no-op (your code must recognize the commands).

How do I test my interpreter? It takes too long to evaluate the chain!

To prevent this issue, each answer must contain a test program for the next answer. The test program must use all commands in the interpreter, in the same manner.

Example of an interpreter

An Aheui program:

방망희 (* This program takes an integer as input and puts it in a stack (방),
          prints it as integer (망), and then terminates (희) *)

Invalid interpreters in Mathematica:

Print[Input[];Input[]]
(* This does not interpret the previous solution; it just does the identical task, ignoring the first input (the Aheui code) *)

If[Input[]=="방망희", Print[Input[]]]
(* This doesn't define each command *)

Fold[Switch[#2, "방망", Print[Input[]], "희", Abort[]]&,, Input[]]
(* This doesn't define each command *)

Valid interpreter in Mathematica:

Fold[stack={}; Switch[#2, "방", AppendTo[stack, Input[]], "망", Print[Last@stack];
  stack = Most[stack], "희", Abort[]]&,, Input[]]

Rules

• Loopholes are not allowed
• Any four consecutive answers cannot contain the same language twice.
• The second to last submission (i.e. proven not to break the chain) by Feb 12 (0:00 UTC) will be the winner.

Answer format

4. [Language](https://link.to.specifications)

Your code here

This answer interprets language XYZ.

[Try it Online!](https://tio.run/nexus/language#@___/___)

Explanation

code snippet

This part interprets the x command.

code snippet

This part interprets the y command.

List of commands

A, B, C, D

Test program

... A( ... ); B( ... ); C( D( ... ) ); ...

Answer 11

Chicken

No, before you ask,this challenge is not about the language.

Chicken is a game played with two cars (or two computers) where two drivers face each-other on a street. Each car may swerve or stay fixed in its path. Here is an idealized payoff matrix

              Player 1
                  Swerve        Stay
Player 2 Swerve    +3/+3        +10/+1          
Stay                +1/+10      -25/-25    

The values given for both swerving reflects the lack of ego damage, +3 is given for a win, but both staying results in a bothersome predicament with a high risk of a crash and where both have to reverse.

Now your job is to write a bot that will play this game. You will be provided with needed information as command line arguments.

A sample invocation will look like this.

foolanguage myBot.foo 4 w,w,w,w,w,w,t,w

Where the first command line argument is a string containing the number of goes you have had in the match and the second is a list containing each of you and your opponents decisions respectively (w is swerve and t is stay). Here is a break down of the list.

 (your first move),(opponents first move),(your second),(opponents second) 

This will be set up in a round robin fashion. You will play some arbitrarily high (say 100) rounds against each bot and your score will be totalled. Least damaged bot (highest scoring bot) wins!

---

Entering

You will provide a command stem and a unique bot name. So the sample bot can be called fooBot, and the command stem (after which arguments are appended) looks like "foolanguage myBot.foo"

Your bot will then output w (swerve) or t (stay) with 50 ms.

Your bot must be be able to make both choices. No locking in to just one choice.

Also, your bot must be deterministic (prng's may be seeded with a private seed. If you wish to do this, insert a dummy seed, and change it right before the competition) please publish the has to ensure you don't tweak it in light of other submissions.

---

The payoff matrix isn't quite realistic, but in order to make this game make sense and various strategies to work, I decided its important to tailor it this way.

Answer 12

This is my first attempt at posting a code golf question. :) The following task is something that I've been thinking about for a while now. To me it seems that most code golf tasks, while often quite amazing, are of little more than of academic interest to anyone. In the modern world (of the World Wide Web), however, RESTful web services are of utmost importance.

I haven't seen many tasks like this here, so I wonder if it's appropriate, or if it needs any additional specs?

---

RESTful Web Service

Your task in a nutshell: implement a web server that can store and return values in a key-value fashion.

Rules

1. Your application must act as a web server on localhost. The TCP port number must be 80 or higher.
2. The server must be usable with the command line tool named curl, which comes pre-installed in every Linux system.
3. The server is essentially a key-value storage where the keys are integers. You may choose to have your keys start from either 0 or 1, i.e. from localhost:80/0 or localhost:80/1. Your server must support storing at least 256 values, i.e. up to localhost:80/255, or /256 if you chose 1-based indexing.
4. "HTTP PUT" to an address must update the value, "HTTP GET" must retrieve it: for example, "curl -XPUT -d 'foo' localhost:80/5" must store the value "foo" into position 5. "curl -XGET localhost:80/5" must then return "foo". "GET" and "PUT" are the only HTTP verbs that need to be supported.
5. The server must always return the HTTP status code "200 OK", unless the user GETs an URL where nothing has been stored yet, in which case the status code must be "404 Not Found".
6. The server must be able to store values that are of at least 64 bytes long.

This is a code golf task, so the shortest answer wins.

Answer 13

How extreme can a letter be?

Challenge

Write a function or program that accepts a rectangular grid of letters (A-Z) as input, and provides an output as follows:

• If the grid contains repeated letters, output the maximum rectilinear distance between two positions on the grid covered by the same letter.
• If every letter in the grid is unique, output 0.

Example

Given this grid:

AEBZWZSFUS
XWHZITHJNN
OQDSLRZFCW
KOMBQQVAGT
FAGIBOZZAX
MECUIFYKYB
UGURYVFHAT
IICZSFMUTC
JPPHXNXSEW
TSUTJMVCNI

...your output should be 17. This is the rectilinear distance between the S on the top right corner and the S on the bottom row.

Rules

This is code golf; shortest code in bytes wins. Standard loopholes disallowed.

Formatting

• Input via standard input, ordered collections (list/array/etc) of strings, or two dimensional array/list/etc of characters is allowed.
• Output via return value, exit code, or standard output is allowed.

Input guarantees

(If the input doesn't comply with these, you don't have to handle it)

• The input is a rectangular grid.
• Every position on the grid is an upper case letter.
• The grid will be at least 2 characters wide.
• The grid will be at least 2 characters tall.
• The grid will be no wider than 98 characters.
• The grid will be no taller than 98 characters.

Output restriction

• Your output should be a single non-negative number indicating the request value.

Test Cases

IXHNBFJFQLQGKEWVCXCX
DVBRMDCGENVDYWDJLADY
FPMTNQHOFPPURUMZXPEJ
ZLOIFSYPKLXFOYOIKUMJ
LKZOSZWWKLWLFZBQQLYJ
-> 19

ABCDEFG
HIJKLMN
OPQRSTU
-> 0

DSMPAHNP
JUWYNWOE
AIUOCIPY
MHODAXVG
NFETRIWH
YDQYVLZL
LDTZBYER
JEXPFRDR
-> 13

ZYXWVUTSRQPO
TSRQPOZYXWVU
NMLKGIHGFEDC
HGFEDCNMLKGI
-> 7

QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
-> 40

code-golf grid

Answer 14

Blank Card + Jera + Batteries

mathnumbergamecode-golf

---

Background

In the dungeon-style game "The Binding of Isaac", there is a trick involving the use of three items, called the Blank Card, Jera, and the Battery. The Blank Card is a usable item that allows for the use of single-use items repeatedly when charged, the Jera item (single-use) allows for the duplication of items on the ground, and the Battery is a ground item which charges the current usable item. Having all three at once allows the player create as many batteries as they please, allowing them to gather all the player-stat altering items in the game with minimal effort.

However, the number of batteries which appear when repeatedly duplicating the batteries depends on a few things. Say that, at any given time, you have n batteries on the ground. Every time that you grab the battery and use the card simultaneously, you end up with 2n - 1 batteries on the ground (where n is the number of batteries you had just before picking up the battery). Your new n is now the current number of batteries on the ground. This sequence continues with each use of the blank card (hereon referred to as an "iteration").

General Formula

For the sake of clarification, the general formula for this sequence may be found below:

Where b represents the number of batteries and n represents the number of iterations.

Task

Given two positive integers x and y, where x is an initial amount of batteries (b0) and y is the number of iterations to enact (n), write a program or function which finds the number of batteries you end up with on the ground.

Examples

Let f(x, y) be the function defined in the task and let [] symbolize the steps taken to reach the answer (not included in this challenge):

>>> f(1, 5)
1
[1, 1, 1, 1, 1]

>>> f(2, 4)
17
[3, 5, 9, 17]

>>> f(8, 8)
1793
[15, 29, 57, 113, 225, 449, 897, 1793]

Answer 15

Display text in Comic Sans!

I haven't seen any challenges that require outputting text in a variable-width font, and of course I had to pick the best one.

Goal:

Display some text in the font Comic Sans. Characters must be variable width; i should use less space than W, for example. Kerning is not required.

Notes:

Your score is the program size (in bytes).
You may assume that the font "Comic Sans MS" is installed on the computer, or that a font file (or image containing the characters in that font) is in the current directory. Storing additional data in this file is not allowed; it must be a standard font or image file.

Input:

A string containing the text to display. This will only contain printable ASCII characters (32 to 126). This can be passed to a function, typed in by the user, loaded from a file, etc.

Output:

The text written in Comic Sans. This can be saved as an image, or just displayed on the screen graphically. However, direct text output is not allowed. For example, this would not be a valid HTML solution:

*{font-family:"Comic Sans MS"}

<input>

code-golf graphical-output

Answer 16

Crossed out 44 is still regular 44

As it happens, the HTML strikethrough <s>4</s> lines up (at least on some systems) with the crossbar of the number 4 so that the two don't differ in appearance: 4 and 4 look like the same thing. This causes crossed out bytecounts in answers to code golf questions seem a bit confusing if they consist entirely of 4s or if they end or begin with a 4.

For instance, 48 44 34 31 bytes seems a bit silly.

However, there is a way to make the strikethrough over a 4 appear more clearly. If the bytecount begins with the digit 4, adding a non-breaking space (ASCII character 255) before the number will make the strikethrough extend beyond the crossbar of the digit 4. Similarly if the bytecount value ends with 4, the non-breaking space is appended to the end.

For example, 44 becomes  44 , 457 becomes  457 and 64 becomes 64 .

The Goal

The task here is to automate this fix.

Take a string like this: <s>48</s> <s>44</s> <s>34</s> 31 bytes as the input, and output or return the string with added non-breaking spaces at the end of each striken through number that ends with the digit four, and to the beginning of each striken through number that begins with the digit four.

So, for example, <s>48</s> <s>44</s> <s>34</s> 31 bytes becomes <s> 48</s> <s> 44 </s> <s>34 </s> 31 bytes. And here's the difference in effect: 48 44 34 31 bytes becomes  48  44  34  31 bytes.

Be sure to use non-breaking spaces, not regular spaces. Do not add them before or after numbers that are not crossed out. You can assume that all strikethroughs are closed (so there's no <s> that's missing its </s>). If there is anything else than the number inside the strikethrough block, no spaces should be added.

Your solution can be a program or a function. This is code-golf, so the shortest submission (for each language) wins. Standard loopholes apply.

Answer 17

Texplode

koth

---

Texplode is like Hexplode, but played on a tetragonal (square) grid. explains the rules

I/O

You will provide two device files / named pipes / terminals / COM ports / other. One of these will be for input, and the other will be for output.

The input provided to your program will be a series of ASCII numbers n^2 characters long, followed by a ; character. The file will be flushed after this is put into it. The meaning of each number is as follows:

• 0: There are no counters here. You can place here.
• 1: There is one counter here, but it is not yours.
• 2: There are two counters here, but they are not yours.
• 3: There are three counters here, but they are not yours.
• 4: There is one counter here, and it is yours. You can place here.
• 5: There are two counters here, and they are yours. You can place here.
• 6: There are three counters here, and they are yours. You can place here.

These numbers should be interpreted as being laid onto a n by n grid.

The output provided by your program should be a number followed by a ;. The number should be the position in the input stream that your program wants to place a counter. It must be a position that you can place in, otherwise Undefined Behaviour will occur.

Controller

The Texplode engine will be here soon.

Answer 18

Render STL files

code-golfgraphical-output

STL means StereoLithography. It's a common file format, used in 3D printing.

The way it works is quite simple. You change every surfaces to triangles. For example, a cube would have 12 triangles, since it has 6 sides, and each sides has 2 triangles.

In this challenge, you have to read STL(A) files and render them.

---

Explain me more about the file format..

^{Well, technically, I linked you to the wikipedia, but I'll just explain, You can just, uh, go to the wiki if you want, you know?}

Alright. the file is in this format.

solid [optional name]
facet normal ni nj nk
    outer loop
        vertex v1x v1y v1z
        vertex v2x v2y v2z
        vertex v3x v3y v3z
    endloop
endfacet
endsolid [optional name]

The part you have to look is the vertexes. you can see there are 3 vertexes each with three numbers (each of them are coodrinates of each axes). Remember I told that you change every surface to triangles? These three vertexes form a triangle.

and the part between facet normal and endfacet will be given multiple times, forming multiple triangles, forming a 3D object. like the cube I told you before.

You do not have to look at the numbers right after the facet normal. it will not affect the shape. (at least in this challenge)

---

Examples

I couldn't copy all of them so I decided to leave a link.

Answer 19

Sandbox notes

• This is the first time I write a controller; and it's been a while since I wrote an actual program. If you feel so inclined, feedback is appreciated.

Initial draft of the controller (java) here: https://github.com/S119349/cooperative-koth

---

king-of-the-hill The Cooperation Game

king-of-the-hill card-game java

In this king-of-the-hill challenge, instead of competing, players will have to work together to beat a game. The player who on average gets the best results over all game runs, is the winner for this challenge. The game is inspired on the mechanics of "The Game".

Game mechanics

The goal of the game is to play as much cards as possible on four piles on the table. Two piles can only accept cards in strictly increasing order, the other two in strictly decreasing order. The game is over as soon as a player cannot play a card.

Piles

The game starts with four piles, numbered 0 through 3 inclusive. Piles 0 and 1 accept cards in strictly increasing order; piles 2 and 3 accept cards in strictly decreasing order. Initially, the piles are

Pile number |  0  |  1  |  2  |  3  |
       Card |  1  |  1  | 100 | 100 |

There is an exception to the rule of accepting only strictly increasing/decreasing order. You are allowed to play a card exactly 10 less or more respectively than the current card. For example, if the piles are

Pile number |  0  |  1  |  2  |  3  |
       Card |  1  |  32 |  78 | 100 |

you are allowed to play 22 on pile 1, or 88 on pile 2.

Taking turns

The game starts with a shuffled draw stack containing 98 cards, numbered 2 through 99 inclusively. Each player is dealt 6 cards at the start of the game. The cards are known only to the players themselves.

During a turn, a player must play at least two cards ^{Exception: you only have one card, or you're out of cards, because the draw stack is empty}, up to all the cards in their hand. After their turn, the player will restock from the draw stack to 6 cards (or less at the end of the game).

Reacting

After each card is played, other players are allowed to react: if you have the perfect card in your hand, you may want to warn players not to add anything to that pile! Since your cards are secret to you, this is done by assigning priorities to each pile. The priority is from 0 to 5 inclusive, with 0 signifying no interest at all in that particular pile, and 5 begging other players not to add anything to that pile. Other players can use these priorities as they deem fit; including completely ignoring it.

Interaction with the controller

You will create a player that extends the abstract Player class. You will have to implement void turn() (for playing a card) and int[] react() (for announcing your priorities). A reference implementation, SimpleTom, is provided, but may be removed from the competition if there are enough competitors.

In void turn(), you are required to either playCard(int card, int pile) or endTurn(). Note that you may only play one card per invocation of turn(), to give other players an opportunity to react(). Doing anything else (playing two cards, playing no cards at all) will result in losing the game, with all the cards still in the game adding towards each player's score!

In int[] react(), you are required to return an array of your priorities on each pile. An example would be return new int[] {a, b, c, d} with a through d the priorities for each pile. Here, 0 <= a <= 5.

To see what is happening, you have access to some members

• ArrayList<Integer> hand contains all cards currently in your hand.
• In the gameState member of the default Player class:
  • int [] gameState.piles contains the four piles. It is an integer array of size 4, with each element the last played card on that pile.
  • Map<Player, int[]> gameState.priorities. A map containing the latest priorities issued by each Player in the game.
  • Player[] gqameState.players can be used to list all the players in the current game; as well as determine how many cards they have by calling int nHandCards(). Note however that you may not access these players in any other way! (force them to do a turn, force them to lose, make them expose their hand, etc).

Concerning the other players: you may know who is playing and assess their skill during a game (for example, figure halfway through a game that SimpleTom is not trustworthy, and that two of the other players are of type SimpleTom). You may not save this information between games, or hard-code strategies concerning other players.

Do's and don'ts

All entries are open-source. You are encouraged to write commonly used functions (e.g., something to keep track of what cards have already been played) as separate functions, so others may use them. When you use code from others, always attribute your source. It is not OK to copy someone's algorithm and just tweak a few values - your code should be significantly different from others.

You are allowed to use a different languages than Java, if you write your own wrapper class (or use someone else's wrapper class). I usually only use Try it Online!, so I don't have any compilers installed on my Ubuntu box. If you use another language that is not available on Ubuntu by default, please include a few lines on how to install your language. Your entry will be non-competing if it takes me more than two minutes to follow these instructions, so a script or copy-pasteable command line code is preferred.

Answer 20

Hex address to little endian escaped string

You are a brilliant hacker and you just gained access to a unprotected computer! To complete your exploitation, you need to convert a set of hexadecimal addresses into a different format.

You remember your lessons from university and you find out the machine you're on is little endian, meaning the order of the bytes is "reversed".

To make a break from your illegal activity, you decide to code a little program that does that automatically.

The Goal

Convert a string of the form

0x12345678

to

\x78\x56\x34\x12

You set up a few tests and their potential results:

0x080483b4   =>   \xb4\x83\x04\x08
0x00000fff   =>   \xff\x0f\x00\x00
0xfffffff0   =>   \xf0\xff\xff\xff
0xefbeadde   =>   \xde\xad\xbe\xef

Rules

The input is of the form 0xXXXXXXXX and the output must be of the form \xXX\xXX\xXX\xXX. The input will always be 10 chars long and the output must be 16 chars long.

The score is the number of bytes used to write the encoding function. If the input string appears in the solution (i.e. not passed as an argument) it is not taken into account. The display of the result is implied (e.g. no need to print, puts, ...).

Answer 21

Implement Fizz Buzz in the C Preprocessor without the use if #if code-golf restricted-source

Note: I understand that there is already a question for Fizz Buzz and the preferred method is to place a bounty on an existing question instead of asking a new one. However, I believe that this warrants its own question.

The C Preprocessor Language is Turing Complete when used in a loop. Your task is to implement Fizz Buzz up to and including a given integer without the use if #if.

• You must be able to implement Fizz Buzz for inputs from 6 to 100. You can support more if you wish, but it is not required.
• #define INPUT <input> will be placed at the top of the file to provide input. This is not included in your bytecount.
• The output is defined as the output of cpp compilation with all lines beginning with # stripped away fed back into cpp for as many times as needed until the results of two steps are identical.
  • You must be able to prove this takes a finite amount of steps.
• Specify the version of the C Preprocessor Standard to use.
• No custom compiler flags.
• No using compiler extensions.
• You can delimit items with the delimiter of your choice.
• There can be extra delimiters at the start.
• Trailing newlines are allowed.
• #if is not allowed!
• It must be exactly Fizz, Buzz, and FizzBuzz. Case sensitive.

A submission might look like this:

#define MAIN(...) \ 
  // ... 
MAIN(INPUT)

It will be compiled as

#define INPUT <input>
#define MAIN(...) \ 
   // ... 
MAIN(INPUT)

...using the command cpp filename.

Steps for getting output:

1. cp file file2
2. cp file2 file
3. cpp file > file2
4. Remove all lines beginning with # in file 2.
5. If file2 is identical to file, exit. The current file2 is defined as the output.
6. Repeat steps 2-5 until exit.

Examples

Multiple outputs for a single input indicates all are valid

6 -> 1, 2, Fizz, 4, Buzz, Fizz
6 -> 1, 2, Fizz, 4, Buzz, Fizz, 
6 -> , 1, 2, Fizz, 4, Buzz, Fizz
6 -> , 1, 2, Fizz, 4, Buzz, Fizz, 
15 -> 1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, Fizz Buzz,

Answer 22

Nibbles Nostalgia

People from my generation certainly know what is the Nibbles game! If you are not here included, what I am asking is a one-line version the level 1 of https://www.youtube.com/watch?v=UmeKHtei0qo (time: 14s—54s)

The challenge is to write a game that is a one line, one level Nibbles game using only the line buffer.

Rules:

• You must output to one or both of stderr/stdout
• Line Width is 80 chars
• Snake will always begin at the middle with 2 chars in width
• For a user to loose, the head of the Snake must hit one of the ends
• Each time a number {1...9} is catched the snake grows using the formula new_witdh= current_width + 2 * catched_number
• Of course numbers appear in an random position of the white space, never in Snake's body
• The char for each snake block body is ASCII \219 █
• It only accepts two keys, the Arrows for Left and Right. Does nothing when in the same sense; inverts head and tail when inverse
• First move is always to right
• It must be available somewhere online for me to play
• Timing between each turn of snake movement is 200 ms (This will be adjusted to make it more realistic)
• If user looses, you will output in the same line a full line of ASCII \127 char ⌂ and quit.
• If user wins, you will output in the same line a full line of ASCII \2 char ☻ and quit

It is a [code-golf] challenge, where there will be no accepted answer; I just made the challenge for my own fun!

UPDATE: I made a nice discovery: The original game is playable on http://stevehanov.ca/blog/index.php?id=92, by mouse clicking on Compile and Run

Answer 23

Caps Lock Morse Code

Inspired by Blink the CAPS LOCK

Input will be a string that contains only characters that can be represented in morse code.

Convert the input string to morse code and then output it using either the Caps Lock, Num Lock or Scroll Lock indicators on the keyboard

Thoughts on the challenge

• I think this would be good as a code golf
• How specific should I be on defining what the output looks like, is the above sufficient or should a specific time length be given for dots and dashes?

Answer 24

Free the Prisoners

code-golf

Your task is to free a few prisoners. Here they are, in their cells:

[sad] [shame] [cops]

---

Rules, explained

They have to be specifically freed using whitespace as replacement for each replaced letter, and then place the words to the right of the string, with an additional space separating the string area.

The first example would become:

[   ] [     ] [    ] sad shame cops

Here is a code snippet that lets you see the prison cell before and after, plus a JS function. The square brackets ([]) are assumed, and do not need to be typed in the box.

console.log(`Original Cell:     Waiting for input...`);
  console.log(`Emptied Cell:      Waiting for input...`);
  console.log(`Empty Cell Length: Waiting for input...`);

var string = '';
var emptyCell = function(string) {
  string = string.replace('[', '').replace(']', '');
  return ' '.repeat(string.length);
};

window.onkeyup = function() {
  string = document.getElementById('cagecontent').value;
  
  console.clear();
  
  console.log(`Original Cell:     '${string}'`);
  console.log(`Emptied Cell:      '${emptyCell(string)}'`);
  console.log(`Empty Cell Length: ${emptyCell(string).length}`);
};

<textarea id='cagecontent' placeholder='Place text, minus the brackets, here.'></textarea>

There is one known error for this script: the first bracket rule doesn't work. Sorry about that.

Any whitespace on the edge of an imprisoned string (ex. test with a space before) would stay while emptying the cells, but would be trimmed when placed outside. The aforementioned test with some extra whitespace on the edge would look like this:

[ test]
[     ] test

As you can see, instead of two spaces between the original string and the freeing area, there is only one.

[test]]
[    ]] test

Rules, simplified

• Trailing spaces are allowed.
• Replace each character in a prison cell string with a single blank space.
• Place each freed thing to the right of the original string.
  • Separate the original string and the freed things with a single space.
  • Extra whitespace on the sides of a string, when placed to the right of an original string, is removed.
• Your testing string will be: (Let us out!)>[mad] [angery] [11]]
  • Should result in: (Let us out!)>[ ] [ ] [ ]] mad angery 11
• No common loopholes, of course.

Scoring

If you look at the tags, you can see that this question is a code-golf puzzle. The tag wiki excerpt for this tag is:

Code-golf is a competition to solve a particular problem in the fewest bytes of source code. If you want to score by characters instead of bytes, please state this explicitly in the challenge. If source code length is not the primary scoring criterion, consider using another tag instead.

That means, the question (of any language) with the least amount of bytes is the top-scoring solution!

Answer 25

Is this bitstring divisible by 3?

code-golf binary string decision-problem

---

Your challenge is to write a program or function that, given a string of bits representing a positive integer, outputs or returns a truthy value if it's divisible by 3, and a falsy value otherwise.

Rules

• You may not convert the input to a number in any way. You may manipulate the string or loop through each digit, so long as you don't convert it to your language's native number type.
• Input may be given as a string or an array of digits.

Truthy examples

11
110
1001
1100
1111
10010
10101
11011
111111
10010011
1010010001
10101010101
100100101010001011110101010001
1000000000000000000000000000000000000000000000000001
1111111111111111111111111111111111111111111111111111
11000001001011110010001010001001010110000010100001001000100101
1111001111110010001110111011001010100100001000110100010011101011110010010111100111011100110101000011100110011111001010000111011110010111000100001010101001000001111011011111000101001111010010010010000110101100011001011111111000111001110110011011101010011000

Falsy examples

1
10
100
101
111
1000
1010
1011
1101
10000
11111
10101010101011
1101001000100001000001000000100000001
10000000000000000000000000000000000000000000000000001
11111111111111111111111111111111111111111111111111111
11000001001011110010001010001001010110000010100001001000100110
1101011111110011110010011101010011000001101011001111001001011010100000000110001111001101100000001010010111100111000101001001000011100000110111010010100000100001100101110000011010000010110010101011110010100110101100000011101101010000010011000001001001010101

---

Sandbox questions

Obviously as a Do X without Y question this is walking a very fine line. There are several string manipulation techniques (which I won't spoil here) that I'd like to see used, rather than solutions that just loop through the string and repeatedly add a digit and take modulo 3. I could be more strict and not allow any numbers in the process, but I don't know if that's a good idea... Suggestions? Is it even possible to make this a good challenge?

Answer 26

Leaderboard golf: posted

Answer 27

The Mass Murderers of Josephus

Everyone knows the Josephus challenge and its setup: you arrange n people in a circle, and the first person kills the second, and from then on the first alive person to the right of the previous "killer" kills the next alive person to their right. For example, with four people:

  1
4   2    (4 people in a loop)
  3

  1
4        (1 kills 2)
  3

  1
         (3 is closest to the right of the previous killer 1,
  3       and kills 4, who is to the right)

  1      (1 is closest to the right of the previous killer 3,
          and kills 3, who is to the right)

The last remaining person is 1, in this case.

Your task, however, is to find the most murderous of these people - or whoever killed the most people. In the above example, the "murderer" is 1, who killed 2 people: 2 and 3.

In a bigger example, of 10 people (this is a line of 10 people, right wraps around to the left):

PEOPLE ALIVE  | KILL TALLY
1 2 3 4 5 6 7 |
1   3 4 5 6 7 | 1: 1
1   3   5 6 7 | 1, 3: 1
1   3   5   7 | 1, 3, 5: 1
    3   5   7 | 1, 3, 5, 7: 1
    3       7 | 3: 2; 1, 5, 7: 1
            7 | 3, 7: 2; 1, 5: 1

There's a tie for the person with the most kills: when a scenario like this arises, the answer is average of all the people with the most kills - in this case, it is (3 + 7) / 2 = 5.

Task:

You must make a program or function that takes one input, the amount of people in the circle, and output the murderer (or the average of multiple murderers).

Rules and specs:

• The input will never be above 2^31 - 1.
• The input is guaranteed to be a positive integer.
• Your program must work out 100 within the timeframe of TIO (60 seconds). If you're not using TIO, provide an interpreter for me to test your program on (preferably an online one).

Answer 28

Chemistry 101

Question

Given the atomic number of an element in the range [1-118] print out the group and period, of that element as given by the following Periodic Table Of Elements.

For elements in the Lanthanide and Actinide series, (ranges [58-71] and [90-103]), you should instead print L for the Lanthanides and A for the Actinides

You may write a program or a function and use any of the our standard methods of receiving input and providing output.

You may use any programming language, but note that these loopholes are forbidden by default.

^{[Source] I couldn't have put it better!}

[Source]

Test Cases

The output here separates the group and period with a single space

| Input | Output |
|   1   |  1 1   |
|   33  |  15 4  |
|   45  |  8 5   |
|   71  |  L     |
|   93  |  A     |
|   117 |  17 7  |

Scoring

Simple code-golf. Shortest number of bytes wins

Answer 29

Android Lock Screen Art

graphical-outputpermutationscode-golfgrid

---

Background

In the land of Android, there exists a password type that looks like this:

It's essentially a connect-the-dots for a password. Today, we'll be making art with it.

The Task

Your program should export as many distinct combinations of pattern lock as image files with the following specifications:

1. Images should be 500x500 pixels large.
2. Dots should be located at positions (x, y):
   • (125, 125)
   • (125, 250)
   • (125, 375)
   • (250, 125)
   • (250, 250)
   • (250, 375)
   • (375, 125)
   • (375, 250)
   • (375, 375)
3. Lines should be drawn with a circular brush head of radius 8px.
4. Background color and line color may be any color of your choosing, but must not be the same color and it must be consistent.
5. The pattern should pass through all points ONCE, with the exception of the first point, which should be the first and last point drawn from/to.

Examples

The following output is valid (starts at top-left):

The following output is valid:

The following output is invalid:

This breaks condition 5 (repeat use of top-left, middle, and middle-left).

The following output is also invalid:

This passes through the top left twice and the start point is not the same as the end point (breaks rule 5 twice).

Scoring

The program with the largest number of distinct outputs wins, with the shortest program being the tiebreak.

Answer 30

All your base are belong to us 6 * 9 = 42

When Douglas Adams wrote THHGTTG, he just made up a formula for the answer to Life, the Universe and Everything. And then some spoilsport pointed out that it was a valid formula... when interpreted in base 13.

Given an input formula, please output as many bases as you can find where the formula is valid.

You must at a minimum support base 10 to base 16 inclusive, but you are strongly recommended to support base 2 to at least base 36.

You must at a minimum support the ()*+= operators, but you are strongly recommended to support - and /, and either ** or ^ for exponentiation. Note that the division will always be exact in valid bases, but may not be exact in invalid bases, so for 11/2=8 you should only output 15.

Examples

11/2=8
15

10+10=10*10
2

6*9=42
13

11**11=2101
3

This is code-golf, so the shortest answer that breaks no standard loopholes wins.