Sandbox for Proposed Challenges

Question

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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.

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Answer 1

Output every string

code-golf

Your task here is simple. Write a program, in as few bytes as possible, which prints every single possible string. Your program should, given infinite memory, never terminate, however for any given string there should be a finite time to be generated. (that is, a aa aaa aaaa ... Won't work as it will never generate b).

The strings to be generated should consist of all the characters in the same encoding as your answer, which you must specify if not utf-8.

The exception is that you must choose a character to exclude from your strings, which you will use to delimit strings. You may optionally have one leading delimiter.

Remember to include the empty string!

Answer 2

Arrange ranges of numbers in columns

Write a program to print from m to input n with step s, arranging the numbers in either horizontal or vertical columns.

Clarifications

• You can use any two values, or kinds of values, for signifying horizontal and vertical columns, specifying these in your answer.

Test cases

from:
m = 1, n = 15, s = 1, vertical columns
to:
         111111
123456789012345

from:
m = 1, n = 11, s = 2, horizontal columns
to:
1
3
5
7
9
11

from:
m = 1, n = 11, s = 2, vertical columns
to:
     1
135791

Any more clarifications or test cases?

This challenge is based on a chat mini challenge by Helka Homba, which is allowed to be used in real challenges under the conditions of Calvin's Hobbies Public License.

Answer 3

Natural Order Sorting

Goal :: Writing a sorting algorithm that doesn't need preceding zeroes to sort music files properly.

Natural Order Sorting will be defined in this way:

• Consecutive Digits (ie [0-9]+) are considered one character and its value is the evaluation of those digits as an integer (eg int("0123"))
• Uppercase Letters (ie [A-Z]) are each their own character and its value is the ASCII value of the letter
• Lowercase Letters (ie [a-z]) are each their own character and its value is the corresponding uppercase value plus .5
• Symbols (ie [^0-z]) are each their own character and its value is the ASCII value of the symbol
• Symbols are always before Digits which are always before Letters
• If two characters are in the same category, the one with the small value precedes the other

Specification

• Input :: An unordered list of strings (flexible on how)
• Output :: A list of strings that are naturally ordered (flexible on how)
• Victory :: Shortest program/function in bytes, wins

Test Cases

Input                             Output
-----                             ------
10,11,8,9                      -> 8,9,10,11
appleA,CiderB,AppleC           -> AppleC,appleA,CiderB
File1,File12,File143A,File031B -> File1,File2,File031B,File143A

code-golfsorting

Answer 4

Source code standard deviation

Your program should accept as input a string, convert it to a unsigned byte array using UTF-8 encoding and output the standard deviation of the n bytes.

Standard deviation is given by this formula, where x1...xn are the string's bytes:

Example

Input hello:

• UTF-8 encoding returns the list [104,101,108,108,111]
• mean is 106.4
• standard deviation is 3.49857113690718

More test cases:

• ppcg: 5.678908345800274
• aaaaa: 0
• azazaz: 12.5
• smiley☺: 41.12432220162674

Scoring

Your score is the standard deviation of your source code, using the above algorithm, divided by the length of your source in bytes, using UTF-8 encoding. The higher the better.

For example, the score for the program hello is: 3.49857113690718 / 5 = 0.699714227381436

Related: Calculate Standard Deviation

Answer 5

The many errors of twin primes

code-golf primes classification

---

Note: this is a repost of my earlier challenge, but with a different winning condition and better rules.

Background

Bob was handed the following assignment for his programming class (this is not the actual challenge).

Homework assignment 11: Twin primes

Take as input an integer n ≥ 8 and print a single character, depending on n:

• If n is not a prime number, print N for "Not prime".
• If n is a prime number, but neither of n - 2 and n + 2 is, print I for "Isolated prime".
• If n and n + 2 are both prime numbers, print L for "Lower twin prime".
• If n and n - 2 are both prime numbers, print U for "Upper twin prime".

Bob tried hard to solve the assignment, but his program kept crashing, and in the end, he gave up and submitted it in hope of partial credit. Nevertheless, Bob's program has the curious property that even though it never does what it's supposed to, the input is still classified correctly depending on the program's behavior: non-primes result in no output, isolated primes in a crash, lower twin primes in an infinite loop with no output, and upper twin primes in an infinite loop that keeps printing the correct message.

The Task

Your task is to replicate the behavior or Bob's solution: you shall write a program or function that behaves as follows. Your input is a single integer n ≥ 8.

1. If n is not a prime number, print nothing and exit gracefully.
2. If n is a prime number, but none of n - 2 or n + 2 is, print nothing and exit with a runtime error of some kind (like stack overflow or division by 0).
3. If n and n + 2 are both prime numbers, print nothing and keep running indefinitely (or until you run out of memory).
4. If n and n - 2 are both prime numbers, repeatedly print the character U to STDOUT indefinitely (or until you run out of memory). The output can contain newlines, commas or other separators.

Input can be taken with any of our default methods, but all output must go to STDOUT (and STDERR in case of error) or closest alternative.

The lowest byte count wins.

Test cases

8 -> [no output]
9 -> [no output]
10 -> [no output]
11 -> [infinite loop]
12 -> [no output]
13 -> UUUUUUUUU[continues indefinitely]
14 -> [no output]
15 -> [no output]
16 -> [no output]
17 -> [infinite loop]
18 -> [no output]
19 -> UUUUUUUUU[continues indefinitely]
20 -> [no output]
21 -> [no output]
22 -> [no output]
23 -> [runtime error]
29 -> [infinite loop]
31 -> UUUUUUUUU[continues indefinitely]
37 -> [runtime error]

---

Sandbox notes

To keep the rules simple, I decided to only allow output to STDOUT.

Answer 6

Prime Factors that Weren't there Before

Given a list of integers a, calculate the prime factorization for each integer in the array. Then, return a list of factors that do not appear in the original input, even as part of another number. For instance, if you were given:

a = [1243,11311]

The prime factors would be calculated as:

a' = [[11, 113], [11311]] = []

Because 11 appears in 11311, and 113 appears in 11311, the result would be [], an empty set.

---

Lets look at another example:

a = [270,325,192] = [[2, 3, 3, 3, 5], [5, 5, 13], [2, 2, 2, 2, 2, 2, 3]] = [13]

---

Another example:

a = [27072,32585,19296] a' = [[2, 2, 2, 2, 2, 2, 3, 3, 47], [5, 7, 7, 7, 19], [2, 2, 2, 2, 2, 3, 3, 67]] a'' = [47,67]

---

A bigger example:

a = [56,3924,10000,1240124]
a' = [[2, 2, 2, 7], [2, 2, 3, 3, 109], [2, 2, 2, 2, 5, 5, 5, 5], [2, 2, 31, 73, 137]]
a'' = [7,109,31,73,137]

This is code golf, lowest byte-count wins.

Answer 7

Play time

Hello. It is time to play the most popular portuguese card game: Sueca! So for people who does not know the game, it is needed to print a wall poster to make them know the power and the points each card has.

So, the job is to print an ASCII art wall as:

    11        10        4         3         2        ———       ———       ———       ———       ———

╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ 
|A     A| |7     7| |R     R| |V     V| |D     D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♥     ♥| |♥     ♥| |♥    /♥| |♥    /♥| |♥    /♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| 
|       | |  ♥ ♥  | | ♔ /  | | ♗ /  | |  ♕ /  | |  ♥ ♥  | |  ♥ ♥  | |  ♥ ♥  | |       | |   ♥   | 
|   ♥   | |   ♥   | |   /   | |   /   | |   /   | |  ♥ ♥  | |   ♥   | |       | |  ♥ ♥  | |       | 
|       | |  ♥ ♥  | |  / ♔ | |  / ♗ | |  / ♕  | |  ♥ ♥  | |  ♥ ♥  | |  ♥ ♥  | |   ♥   | |   ♥   | 
|A     A| |7 ♥ ♥ 7| |R/    R| |V/    V| |D/    D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| |♥     ♥| 
╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ 

╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ 
|A     A| |7     7| |R     R| |V     V| |D     D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♦     ♦| |♦     ♦| |♦    /♦| |♦    /♦| |♦    /♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| 
|       | |  ♦ ♦  | | ♔ /  | | ♗ /  | |  ♕ /  | |  ♦ ♦  | |  ♦ ♦  | |  ♦ ♦  | |       | |   ♦   | 
|   ♦   | |   ♦   | |   /   | |   /   | |   /   | |  ♦ ♦  | |   ♦   | |       | |  ♦ ♦  | |       | 
|       | |  ♦ ♦  | |  / ♔ | |  / ♗ | |   / ♕ | |  ♦ ♦  | |  ♦ ♦  | |  ♦ ♦  | |   ♦   | |   ♦   | 
|A     A| |7 ♦ ♦ 7| |R/    R| |V/    V| |D/    D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| |♦     ♦| 
╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯

╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ 
|A     A| |7     7| |R     R| |V     V| |D     D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♣     ♣| |♣     ♣| |♣    /♣| |♣    /♣| |♣    /♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| 
|       | |  ♣ ♣  | | ♚ /  | | ♝ /  | |  ♛ /  | |  ♣ ♣  | |  ♣ ♣  | |  ♣ ♣  | |       | |   ♣   | 
|   ♣   | |   ♣   | |   /   | |   /   | |   /   | |  ♣ ♣  | |   ♣   | |       | |  ♣ ♣  | |       | 
|       | |  ♣ ♣  | |  / ♚ | |  / ♝ | |  / ♛  | |  ♣ ♣  | |  ♣ ♣  | |  ♣ ♣  | |   ♣   | |   ♣   | 
|A     A| |7 ♣ ♣ 7| |R/    R| |V/    V| |D/    D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| |♣     ♣| 
╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ 

╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ ╭───────╮ 
|A     A| |7     7| |R     R| |V     V| |D     D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♠     ♠| |♠     ♠| |♠    /♠| |♠    /♠| |♠    /♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| 
|       | |  ♠ ♠  | | ♚ /  | |  ♝/  | |  ♛ /  | |  ♠ ♠  | |  ♠ ♠  | |  ♠ ♠  | |       | |   ♠   | 
|   ♠   | |   ♠   | |   /   | |   /   | |   /   | |  ♠ ♠  | |   ♠   | |       | |  ♠ ♠  | |       | 
|       | |  ♠ ♠  | |  / ♚ | |  / ♝ | |  / ♛  | |  ♠ ♠  | |  ♠ ♠  | |  ♠ ♠  | |   ♠   | |   ♠   | 
|A     A| |7 ♠ ♠ 7| |R/    R| |V/    V| |D/    D| |6     6| |5     5| |4     4| |3     3| |2     2| 
|♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| |♠     ♠| 
╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯ ╰───────╯

Answer 8

Left-to-Right calculator

Given the opinion I posted on https://ux.stackexchange.com/a/99984/51560 , I want to have a calculator where the least-significant least digits are placed on the left.

The input must come from stdin. It only needs to support non-negative integers. Additions must support any number of parcels, and to end the input of parcels input an empty line. In every example, all above the first ——— line is input, the first ——— line itself and the lines below are output.

Example:

+
2134
254
89
————
0684

Subtractions input is always composed by two operators:

-
3351547
945613
———————
4894317

Multiplications input is also two operands.Must support at multiplications where the second operator is < 100 and output the auxiliary addition like the way it is done by hand.

*
94651
74
———————
345901
 69526
———————
305537

Answer 9

Contiguous Palindromic Subsequencing

Given a word a, perform the following operations:

1. Group string into palindromic subsequences of length > 2 and non-palindromic subsequences. (You should prioritize partition length over partition index, for instance esse shouldn't result in ['e','ss','e'], it should be ['esse']. However, if the lengths are the same for two subsequences, use index to prioritize which you choose).
2. Make all non-palindromic subsequences palindromic (single characters are palindromic here).
3. Put it back together.

You may assume only printable ASCII characters are used.

---

Examples:

raggamuffin -> ['r','agga','muffin'] -> ['r','agga','muffiniffum'] -> raggamuffiniffum

bananaracecar -> ['b','anana','racecar'] -> ['b','anana','racecar'] -> Unchanged.

(Since each palindrome grouping would be the same length, use the first one).
SIZE OF GROUP > INDEX OF GROUP
abaca -> ['aba', 'ca'] -> ['aba','cac'] -> abacac

(Always choose the bigger palindrome, THEN go by index)
cheesewheels -> ['che','ese','wh','ee','ls'] -> ['chehc','ese','whw','ee','lsl'] -> chehcesewhweelsl

(Always choose the bigger palindrome, THEN go by index)
1223224 -> [1,22322,4] -> Unchanged.

abbabbababbababba -> ['a', 'bb', 'abbababbababba'] -> Unchanged.

abcdefg -> ['abcdefg'] -> ['abcdefgfedcba'] -> abcdefgfedcba

slammedintoacardoor -> ['sla', 'mm', 'edinto', 'aca', 'rd', 'oo', 'r'] -> ['slals', 'mm', 'edintotnide', 'aca', 'rdr', 'oo', 'r'] -> slalsmmedeintotniacardroor

eeefffgegffhi -> ['eee','f','ffgegff','hi'] -> ['eee','f','ffgegff','hih'] -> eeefffgegffhih

---

This will be code-golf, lowest byte-count wins.

Answer 10

1 line ASCII Domino play

The game is described on my own question I posted on Domino game maximum achievable points.

The rules for scoring are on the link, and I am reposting them here:

The rules for scoring are: every time a part is placed, if the sum of both ends of the dominoes chain is a multiple of 5, you add it to you current score.

example: [4|2] [2|1] makes 5 points

A double (every part where the two halfes are equal) is always placed rotated by 90º; so for accounting purposes, unlike other pieces, both sides ot the part are taken into account.

Example:

___       ___
|6|       |4|
——— [6|4] ———  
|6|       |4|
———       ———

makes for 20 points.

One single part placed accounts as the two tips.

Example [2|3] accounts as 5 points

And

___ 
|5| 
——— 
|5| 
———  accounts as 10 points.

The challenge is to write a game that is an ASCII one line domino game for me to play.

Rules:

• You must output to stderr/stdout
• Line Width is 80 chars
• The first two chars are reserved for displaying points, aligned at right. By definition, it will always be a multiple of 5; and the third is always a space

• Given space is limited:

  • Every join of two parts will conjoin and they will be separed by a | they will share instead of ][

  • Double parts (those where the two halves are equal) will be represented abbreviate:

    • [ | ] => [ ]
    • [1|1] => [=]
    • [2|2] => [+]
    • [3|3] => [*]
    • [4|4] => [&]
    • [5|5] => [X]
    • [6|6] => [%]
  • Except for white double, all whites are represented by only the other half
  • Every other part is represented by [NM], where N and M are the number of each half
• The ends of the whole dominoes chain are always terminated by []
• The initial state is an empty table. First piece placed will be at the center
• When chain begins to not fit, at one of the ends, it must be adjusted to fit by pushing the whole placing a little bit to the left or the right.
• The last 3 chars of the line are reserved for user input. User can only input a piece not yet placed. User input is NM which is displayed; and a keypress of + or - which will NOT be displayed to avoid a newline feed. The key press tells what side of the chain will the new piece will be snapped:
  • - to left
  • + to right
  • It also must validate the snapping. If user snaps to a non-matching piece, just do nothing. The program will NOT be smart enough to make guesses; so it will NOT make a piece to snap on the other side if piece does not match user specified side
  • And after each valid placing of a piece, must update the points display if there are some to score.

Example of an INVALID placed chain, containing a sequence which would not be possible, because there are pieces snapped to not-matching pieces.

  5 [ |=|+|*|&|X|%|1|2|3|4|5|6|12|13|14|15|16|23|24|25|26|34|35|36|45|46|56] 12{+}

The {+} is not displayed, it is there just to illustrate the input:

Answer 11

Graphical Borromean Rings

Here is an SVG rendering of the Borromean Rings:

<svg xmlns="http://www.w3.org/2000/svg" height="200" width="200">
  <defs>
    <radialGradient id="green">
      <stop stop-color="transparent" offset="70%"/>
      <stop stop-color="#0F0" offset="75%"/>
      <stop stop-color="#CFC" offset="85%"/>
      <stop stop-color="#0F0" offset="95%"/>
      <stop stop-color="transparent" offset="100%"/>
    </radialGradient>
    <radialGradient id="blue">
      <stop stop-color="transparent" offset="70%"/>
      <stop stop-color="#00F" offset="75%"/>
      <stop stop-color="#CCF" offset="85%"/>
      <stop stop-color="#00F" offset="95%"/>
      <stop stop-color="transparent" offset="100%"/>
    </radialGradient>
    <radialGradient id="red">
      <stop stop-color="transparent" offset="70%"/>
      <stop stop-color="#F00" offset="75%"/>
      <stop stop-color="#FCC" offset="85%"/>
      <stop stop-color="#F00" offset="95%"/>
      <stop stop-color="transparent" offset="100%"/>
    </radialGradient>
    <mask height="100" width="100" y="0" x="0" id="back">
      <rect fill="#FFF" height="100" width="50" y="0" x="0"/>
      <rect fill="#FFF" height="50" width="50" y="25" x="50"/>
    </mask>
    <mask height="100" width="100" y="0" x="0" id="front">
      <rect fill="#FFF" height="25" width="50" y="0" x="50"/>
      <rect fill="#FFF" height="25" width="50" y="75" x="50"/>
    </mask>
  </defs>
  <circle mask="url(#back)" fill="url(#green)" r="50" cy="50" cx="50"/>
  <circle fill="url(#blue)" r="50" cy="93.3" cx="75"/>
  <circle fill="url(#red)" r="50" cy="50" cx="100"/>
  <circle mask="url(#front)" fill="url(#green)" r="50" cy="50" cx="50"/>
</svg>

Please write a full program to generate a graphical-image which resembles the above rendering reasonably well. In particular:

• Solid colours, aliased pixels or overlap artefacts are not acceptable
• Your colours should contrast with each other
• Your circles must default to at least 100px in diameter (I wanted larger circles in my snippet but I get a scroll bar if I try)
• Your circles must have the appearance of overlapping impossibly
• Rotations and reflections are perfectly acceptable

Output is via any generally acceptable output format e.g. writing to vector or raster image format or displaying directly to the screen. This is code-golf, so the shortest program wins.

Related: ASCII Borromean Rings

Answer 12

Number that includes the amount of digits of itself

code-golfnumber

Create a number where each digit represents the amount of this digit the number itself contains. Maybe my english is too bad to describe it clearly so here is an example:

6210001000
explanation:
6               -> this number contains 6 times '0'
 2              -> this number contains 2 times '1'
  1             -> this number contains 1 time  '2'
   0            -> this number contains 0 times '3'
    0           -> this number contains 0 times '4'
     0          -> this number contains 0 times '5'
      1         -> this number contains 1 time  '6'
       0        -> this number contains 0 times '7'
        0       -> this number contains 0 times '8'
         0      -> this number contains 0 times '9'

We will call those numbers self-describing. Each self-describing number must be 10 digits long to be able to represent all digits from 0 to 9.

I have two possible goals for this challenge:

1. Create a program which prints out all self-describing numbers in the range 0000000000 < X < 99999999999
2. For a given integer in the range 0000000000 < X < 99999999999 print out true if it's a self-describing number, else false.

I can add further examples and rules if i move it out of the sandbox.

Answer 13

Digit stream with no 42

You should write a program or function which receives no input and outputs a stream of digits.

• The stream should contain at least once every positive integer number which does not contain the digit sequence 42. E.g. The string 1231 contains the integers 1 12 123 1231 2 23 231 3 31 (and 1 again)

• The stream should not contain the digit sequence 42.

• If your interpreter can't handle infinite output gracefully you can add code to only print the first n digits. This added code does not count to your score.

• Note that the stream 203204205... contains 42.

• No randomness should be used.

This is code-golf so the shortest entry wins.

Do we have infinite output tag?

Answer 14

Where am I?

code-golf(Some other tags pls help)

Your task in this challenge is to output the location of the user. This may be done by means of GeoIP, a builtin GPS device, or any other means. Output should either be in the format (latitude, longitude) accurate to at least one degree, or (City, [optional state/province/etc], Country). Errors due to the GPS device being inaccurate or similar which are not the fault of your code are allowed. Fewest bytes wins.

Answer 15

Do you accept me?

code-golf

---

Introduction

Being accepted is very important to people. But words are also people (right!?). So they also want to be accepted. However most people work non-deterministically and as such it's only fair to transfer that into our decision whether we accept a word. Of course, because a stupid human can't remember much the instructions to decide whether to accept a word must be short...

Input

Your input will be

• a list of non-negative integers - the "word" (this is easier than using strings and actual alphabets)
• a list of triples of non-negative integers - the transitions, you may also use unordered data structures here
• an integer - the starting state
• a list of non-negative integers - the accepting states, you may also use unordered data structures here

You may use any other object or whatever than integers if it pleases you.

Output

A truthy or a falsey value.

What to do?

Basically implement an NFA.
That is, read every single character (ie every number) from left to right and for each one of them look whether there exist a transition from your current state using this character. If so follow it and repeat the process for the next letter. If you face an empty list, your current state must be in the list of accepted states if it is output true and stop examining other paths if it isn't continue examining the other options. If you get stuck (ie the word isn't empty but there's no way to continue), output false.

Who wins?

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

Examples

For the following examples I'm going to use this automaton:

which has starting state 10, accepting states [13] and transitions

[(10,4,11),
(11,4,11),
(11,1,12),
(12,1,12),
(12,3,13),
(13,3,13),
(11,3,13)]

These three parameters are assumed to be also passed in the examples. Word examples for this automaton are:

[1,2,3,4] -> false
[4,1,3,4] -> false
[4,1,3] -> true
[4,1,3,3,3] -> true
[2,1,3,4,3,2] -> false
[4,1,4] -> false
[4,3,1] -> false
[4,3,3] -> true

Answer 16

Simulate a vibrating string

code-golf

Vibrations are an integral part of physics. In this challenge, you will be implementing a simulation of a vibrating string.

This is actually rather easy to do as a result of the Huygens–Fresnel principle, which allows us to use a simulation process similar to cellular automata.

(don't have time to write a full spec right now. Also, I have a 2D version working but figured 1D was enough for a challenge)

Below is an example of a string vibrating at its second harmonic, with each row being 1 tick of the simulation.

  1.00  2.00  1.00 -1.00 -2.00 -1.00
  0.95  1.90  0.95 -0.95 -1.90 -0.95
  0.85  1.70  0.85 -0.85 -1.70 -0.85
  0.71  1.42  0.71 -0.71 -1.42 -0.71
  0.54  1.07  0.54 -0.54 -1.07 -0.54
  0.33  0.67  0.33 -0.33 -0.67 -0.33
  0.11  0.23  0.11 -0.11 -0.23 -0.11
 -0.11 -0.22 -0.11  0.11  0.22  0.11
 -0.33 -0.66 -0.33  0.33  0.66  0.33
 -0.53 -1.07 -0.53  0.53  1.07  0.53
 -0.71 -1.42 -0.71  0.71  1.42  0.71
 -0.85 -1.70 -0.85  0.85  1.70  0.85
 -0.95 -1.90 -0.95  0.95  1.90  0.95
 -1.00 -2.00 -1.00  1.00  2.00  1.00

This challenge is based off the math found on this website.

Answer 17

Task Scheduling code-golf

Given as input:

• A unix time at which to first run the program
• Delay between runs (can be 0)
• Number of times to run the program (-1 if infinite)
• A program to be run through the console when triggered

Run the program under specified conditions.

• You can assume your program will always be running
• Run the equivalent of nohup <command> &.

Answer 18

The many names of Túrin

Tolkien's character Túrin had a multiple personality disorder and consequently needed to change name on a regular basis to be called by something fitting its current mood. He has been known as Turambar, Mormegil, Gorthol, Adanedhel, Dagnir Glaurunga, the Wildman of the Woods, Neithan and some other unofficial nicknames alluding to his tenderness for his sister.

This must have been a real headache for the author: not only had he to find the new names but he also had to remember the translation in English¹, since every new name is introduced along the lines of "From this day he was known as [Compound_Elvish_word], that is [Word of word]"

Your task is to automatize the production of epithets to help Tolkien finish his Unfinished Tales.

Given a list of Sindarin² substantives and their English translations (see list below) as an external file, a list or any reasonable format, randomly take two Sindarin substantives (repetition is possible) and print "From this day he was known as Sindarin1sindarin2, that is English2 of English1"

(Note the inversion of words in the translation, and the capitalisation)

Input: none

Output: A string

The list: (names can be capitalized in your own list, but the formatting must be consistent. The order of the couples can also be changed)

Sindarin    English
--------------------
amarth      fate
ang         iron
aur         morning
brethil     birch
carch       fang
celeb       silver
draug       wolf
galad       glittering
glor        light
gwathel     sister
manadh      doom
megil       sword
melethron   lover
mor         darkness
naur        flame
taur        forest

Examples:

• From this day he was known as Galadaur, that is Morning of Glittering
• From this day he was known as Mormelethron, that is Lover of Darkness
• From this day he was known as Draugdraug, that is Wolf of Wolf

Hobbits played golf and Codë was the Vala of challenges in the Silmarillion, so this is code-golf.

¹ Sorry, Tolkien specialists, I'm probably massacring Quenya, Sindarin and many other concepts

² I think

Answer 19

Minimum exchange of bills

code-golfcombinatorics

You're at the supermarket, buying groceries for the week. At the end, the cashier rings up your cart and declares that your total cost is exactly $76. You reach into your wallet, and find a $50, four $20s, and a $1, for a total of six bills.

We consider a transaction to be you paying money to the cashier, and the cashier giving you your change (if applicable). Your total for a transaction is the net amount of money you owe the cashier, which is calculated by the amount you pay less the amount of change you get. We can think of a transaction as adding the bills you pay to the cashier, and subtracting the bills you get in return. Thus, the following is a non-exhaustive list of possible transactions in this scenario:

$50 + $20 + $20 - $10 - $1 - $1 - $1 - $1 (8 bills)
$20 + $20 + $20 + $20 - $1 - $1 - $1 - $1 (8 bills)
$20 + $20 + $20 + $20 + $1 - $5           (6 bills)
$50 + $20 + $20 + $1 - $10 - $5           (6 bills)

Given a total of $76, and having 1 $50, 4 $20s, and 1 $1, the minimum exchange of bills comes out to 6 bills.

Challenge

Given an integer Bill and a list of bills in your wallet [Ones Fives Tens Twenties Fifties Hundreds], calculate the number of bills in a minimum exchange of bills between you and the cashier.

Rules

1. Your program can accept your input in any reasonable way. You can accept an integer followed by a list of six integers separated by reasonable means. You can accept seven integers separated by any reasonable means. If your language cannot accept input in any reasonable form, you may, at no penalty, hardcode the input into your program. You may only hardcode input if your language cannot reasonably accept meaningful input.
2. Your program must output the number of bills in the minimum exchange transaction. Your program may not print any of the possible transactions themselves.
3. You may assume that you will always have enough money to cover your bill, possibly requiring some change from the cashier.
4. You may assume that the cashier has an unlimited number of all bills at their disposal.
5. You may assume that all inputs are non-negative integers. It is possible that your bill comes out to $0. No integer input will ever be greater than 1000. That's too many bills and quite frankly, too many groceries.
6. This is code-golf, so fewest bytes wins.

Test cases

Input                        Output
[76,1,0,0,4,1,0]              6

I'll come up with and post some more test cases if people think this is a good challenge.

Possible bonus challenge:

In the United States, a $2 is a rare, but legal, bill issued by the treasury. If you wish, you can have your program accept another integer, between the number of Ones and Fives, representing the number of $2-bills you have in your wallet, which you can use to pay for your groceries. However, since such bills are so uncommon, the cashier will not have any on-hand to give to you as change.

Answer 20

loripsum.net

The purpose of this challenge is to emulate the functionality of the loripsum.net website. This website takes in a "number of paragraphs" and a list of randomized HTML5 stylizations and outputs a pre-formatted HTML5 lorem ipsum text that is REALLY good for placeholders on a prototype website. Your code, however, will focus more on the stylization aspect of this website.

---

Given a block of lorem ipsum text in the following format:

<segment> := <paragraph> | <paragraph><new-line><segment>

<paragraph> := <sentence> | <sentence><paragraph>

<sentence> := <character_run><sentence_end>

<character_run> := <printable_ascii_without_newline_or_period>|<pawnop><character_run>

<sentence_end> := \n | . | ? | !

---

Here's an example of a possible input:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quonam, inquit, modo? Progredientibus autem aetatibus sensim tardeve potius quasi nosmet ipsos cognoscimus. Quod non faceret, si in voluptate summum bonum poneret. Duo Reges: constructio interrete.

Tubulo putas dicere? Cum salvum esse flentes sui respondissent, rogavit essentne fusi hostes. Dat enim intervalla et relaxat. Satisne ergo pudori consulat, si quis sine teste libidini pareat? Negare non possum. An hoc usque quaque, aliter in vita? Plane idem, inquit, et maxima quidem, qua fieri nulla maior potest. Quid ei reliquisti, nisi te, quoquo modo loqueretur, intellegere, quid diceret?

Itaque ad tempus ad Pisonem omnes. Universa enim illorum ratione cum tota vestra confligendum puto. Haec dicuntur inconstantissime. Dicimus aliquem hilare vivere; Qui non moveatur et offensione turpitudinis et comprobatione honestatis? Sed quot homines, tot sententiae; Quippe: habes enim a rhetoribus; Omnes enim iucundum motum, quo sensus hilaretur. Tria genera bonorum; Profectus in exilium Tubulus statim nec respondere ausus;

Certe non potest. Dempta enim aeternitate nihilo beatior Iuppiter quam Epicurus; Graece donan, Latine voluptatem vocant. Itaque a sapientia praecipitur se ipsam, si usus sit, sapiens ut relinquat. Quid est igitur, inquit, quod requiras? Atque haec coniunctio confusioque virtutum tamen a philosophis ratione quadam distinguitur. Ego vero volo in virtute vim esse quam maximam;

Verum hoc idem saepe faciamus. Huic mori optimum esse propter desperationem sapientiae, illi propter spem vivere. Si enim ita est, vide ne facinus facias, cum mori suadeas. Indicant pueri, in quibus ut in speculis natura cernitur. Apparet statim, quae sint officia, quae actiones. An est aliquid per se ipsum flagitiosum, etiamsi nulla comitetur infamia? Non autem hoc: igitur ne illud quidem. Res enim se praeclare habebat, et quidem in utraque parte.

---

Your task, given the input t from above, is to apply one formatting operations at random once per paragraph, defined by the following list of operations:

• Character Run Operations (Should be performed on 1-5 word runs chosen at random. This should NEVER cross sentence boundaries (\n|.|?|!))
  • Bold <b></b>
  • Italic <i></i>
  • Underline <u></u>
• Sentence Operations (Should be performed on 1-2 sentences in the paragraph)
  • Block Quote <blockquote></blockquote>
  • Preface <pre></pre>
  • Heading <h1></h1> ... <h6></h6> (Chosen at random)
• Paragraph Operations (Should turn entire paragraph into this format, separated by sentences if the operation is segmented (like a list)).
  • Unordered List <ul><li>Sentence 1</li>...<li>Sentence n</li></ul>
  • Ordered List <ol><li>Sentence 1</li>...<li>Sentence n</li></ol>

So, here is one possible random output:

[1:HEADING(h1 chosen),2:BOLD(4 times),3:PREFACE(1 sentence),4:UNORDERED-LIST,5:BLOCKQUOTE(2 sentences)]

Applied to the input from above (t):

Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Quonam, inquit, modo? Progredientibus autem aetatibus sensim tardeve potius quasi nosmet ipsos cognoscimus. Quod non faceret, si in voluptate summum bonum poneret. Duo Reges: constructio interrete.

Tubulo putas dicere? Cum salvum esse flentes sui respondissent, rogavit essentne fusi hostes. Dat enim intervalla et relaxat. Satisne ergo pudori consulat, si quis sine teste libidini pareat? Negare non possum. An hoc usque quaque, aliter in vita? Plane idem, inquit, et maxima quidem, qua fieri nulla maior potest. Quid ei reliquisti, nisi te, quoquo modo loqueretur, intellegere, quid diceret?

Itaque ad tempus ad Pisonem omnes. Universa enim illorum ratione cum tota vestra confligendum puto. Haec dicuntur inconstantissime. Dicimus aliquem hilare vivere; Qui non moveatur et offensione turpitudinis et comprobatione honestatis?

Sed quot homines, tot sententiae;
Quippe: habes enim a rhetoribus; Omnes enim iucundum motum, quo sensus
hilaretur.

Tria genera bonorum; Profectus in exilium Tubulus statim nec respondere ausus;

• Certe non potest.
• Dempta enim aeternitate nihilo beatior Iuppiter quam Epicurus; Graece donan, Latine voluptatem vocant.
• Itaque a sapientia praecipitur se ipsam, si usus sit, sapiens ut relinquat.
• Quid est igitur, inquit, quod requiras? Atque haec coniunctio confusioque virtutum tamen a philosophis ratione quadam distinguitur.
• Ego vero volo in virtute vim esse quam maximam;

Verum hoc idem saepe faciamus. Huic mori optimum esse propter desperationem sapientiae, illi propter spem vivere.

Si enim ita est, vide ne facinus facias, cum mori suadeas. Indicant pueri, in quibus ut in speculis natura cernitur. Apparet statim, quae sint officia, quae actiones. An est aliquid per se ipsum flagitiosum, etiamsi nulla comitetur infamia? Non autem hoc: igitur ne illud quidem. Res enim se praeclare habebat, et quidem in utraque parte.

Wow! Isn't that much prettier? Here's the code view:

<h1>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</h1> Quonam, inquit, modo? Progredientibus autem aetatibus sensim tardeve potius quasi nosmet ipsos cognoscimus. Quod non faceret, si in voluptate summum bonum poneret. Duo Reges: constructio interrete.

Tubulo <b>putas dicere</b>? Cum salvum esse flentes sui respondissent, rogavit <b>essentne fusi</b> hostes. Dat enim intervalla et relaxat. <b>Satisne ergo pudori consulat, si quis sine</b> teste libidini pareat? Negare non possum. An hoc usque quaque, aliter in <b>vita</b>? Plane idem, inquit, et maxima quidem, qua fieri nulla maior potest. Quid ei reliquisti, nisi te, quoquo modo loqueretur, intellegere, quid diceret?

Itaque ad tempus ad Pisonem omnes. Universa enim illorum ratione cum tota vestra confligendum puto. Haec dicuntur inconstantissime. Dicimus aliquem hilare vivere; Qui non moveatur et offensione turpitudinis et comprobatione honestatis? <pre>Sed quot homines, tot sententiae; Quippe: habes enim a rhetoribus; Omnes enim iucundum motum, quo sensus hilaretur.</pre> Tria genera bonorum; Profectus in exilium Tubulus statim nec respondere ausus;

<ul><li>Certe non potest.</li><li>Dempta enim aeternitate nihilo beatior Iuppiter quam Epicurus; Graece donan, Latine voluptatem vocant.</li><li>Itaque a sapientia praecipitur se ipsam, si usus sit, sapiens ut relinquat.</li><li>Quid est igitur, inquit, quod requiras? Atque haec coniunctio confusioque virtutum tamen a philosophis ratione quadam distinguitur.</li><li>Ego vero volo in virtute vim esse quam maximam;</li></ul>

<blockquote>Verum hoc idem saepe faciamus. Huic mori optimum esse propter desperationem sapientiae, illi propter spem vivere.</blockquote>Si enim ita est, vide ne facinus facias, cum mori suadeas. Indicant pueri, in quibus ut in speculis natura cernitur. Apparet statim, quae sint officia, quae actiones. An est aliquid per se ipsum flagitiosum, etiamsi nulla comitetur infamia? Non autem hoc: igitur ne illud quidem. Res enim se praeclare habebat, et quidem in utraque parte.

Take note specifically of how I split the sentences on the paragraph operators, you delimit by ONLY periods and NEWLINES, nothing else ends a sentence. Also, make not of how the character run operators can span multiple words, BUT NOT MULTIPLE SENTENCES, you must stop before the next sentence begins (EXCLUDING THE ENDING NEWLINE OR PERIOD). As in, it's only applicable to the <character_run> language definition.

This is code-golf lowest byte-count will be declared the winner.

Answer 21

Find square sum products integer math

It's possible to find sets of three numbers whose product including their sum is a square number. Examples:

• (3 + 2 + 1) * 3 * 2 * 1 = 6²
• (3 + 3 + 2) * 3 * 3 * 2 = 12²
• (4 + 4 + 1) * 4 * 4 * 1 = 12²
• (9 + 8 + 1) * 9 * 8 * 1 = 36²
• (8 + 5 + 5) * 8 * 5 * 5 = 60²
• (8 + 7 + 6) * 8 * 7 * 6 = 84²
• (9 + 8 + 8) * 9 * 8 * 8 = 120²

Please write a program or function to find square sum products for me.

Since there are an infinite number of square sum products, even excluding trivial multiples, you should limit your output to depend on a characteristic number N. Your program should always output the same square sum product(s) for a given N, and there should be at least one value of N for each possible square sum product that will cause your program to output that product. However, I will be flexible in what N actually represents, as long as you describe it in your answer. Here are some examples:

• N is one sixth^{[citation needed]} of the square root of the square sum products. For example, an N of 2 would find the second and third of my examples.
• N is the upper bound of the largest summand. For example, an N of 9 would find all of my examples and then some.
• N is the number of square sum products to be found. For example, an N of 12 would find all of my examples and then some.

For the output, I don't actually want the summands or the square root. Instead, please output the pairwise sum of the summands. Please also exclude duplicates (i.e. reorderings) from your answer.

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

Answer 22

Dual Kimian (Error) and Regular Quine Polyglot code-golf polyglot quine

Create a program that is

• a non-erroring proper quine in one language...
• ...and a proper quine that produces its own source code through an error in another language

What is an error quine?

The compiler/interpreter/runtime to produce error output when compiling/running your program which is identical to your program's source code.

• Your program may be specific to a particular version or implementation of your language's compiler/interpreter/runtime environment. If so, please specify the particulars.
• Only standard compiler/interpreter/runtime options are permitted. You cannot pass some weird flag to your compiler to get a specific result.
• The program does not need to be syntactically or semantically valid.
• The program must not produce any output of its own (e.g. by calling print or an output function). All output generated upon attempting to compile/run the program must originate from the compiler/interpreter/runtime.
• The complete output of the compiler/interpreter/runtime must be exactly identical to your program source code.
• The compiler/interpreter/runtime must generate at least one error message when invoked with your program.

^{(adapted from nneonneo's "Make an error quine!" challenge)}

• Polyglots from different versions of the same language or similar languages are allowed

Answer 23

Sandbox Questions

• Is it a good idea to post this as a separate challenge? This one is significantly easier and I fear that posting it would take too much attention away from the original challenge.

---

Detect if your program has been bit-flipped code-golf radiation-hardening

Write a program that outputs

NOT CORRUPTED

If any single bit is substituted by the alternate bit the program should output

CORRUPTED

• Do not read your source code from a file

Answer 24

Binary beads clock

The challenge is dedicated to pseudo-graphical representation of objects, e.g. like by ascii-art. Puzzle is geometrical: to represent bistrings as beads using tiles. The result must be beads-like strings where one is more like a bead and zero is more like a stem (or smaller bead). The solution can result in wide variety of visual concept but there are specific guides, see below.

A simple example of binary beads using single tiles, here standard characters:
Input: 1001, 0101, 0011.
Output:

s--s
-s-s
--ss

or e.g. PETSCII console:

So these are only example form, but now you must "upscale" it, but since you are not in graphical mode, the resulting image must be structure of source units, i.e. it must be a rectangular tiling. In other words. it is not allowed just to draw sprites for each next upscale step. So the whole must be a real console app or code which emulates the console behaviour itself within the guidelines. So you can draw any tiles and use them also. Solution should show some reference to console output, e.g. if using graphical lib, a "print" function should be made which takes the data.

Task

The task is to write an application or function wich draws scalable yet visually consistent beads with efective usage of tiles. Tilesets with least amount of tiles and yet with outstanding rich beads look must win. In other words, one should find good relation between tiles amount and good possibility to present different sizes.

One can present different length strings, but the whole layout must be of adequate size. Multiple words on line is allowed and even welcome especially if shows interesting use case.
Usage of graphical libs is welcome, e.g. to emulate a simple console-like output.
All tiles can be custom, i.e. this should not be necessarily standard characters of console. In real console any characters possible can be used or patched with custom tiles if possible. Any OS can be used.

Restrictions:

Final image:

• must include at least 2 different types of beads (different sizes), i.e. interesting scalability example
• each bead type must share some tiles with other beads
• structures should be good visible from various distance and contiguos as possible
• "zero=stem, ones=bead" rule is not strict, creativity is very welcome but it should be not too far from rule to compare results
• artiscism in forms is always bonus points!

Tiles:

• maximal amount of tiles in the tileset : 16
• are rectangular, e.g 16x8, 8x8 pixels ...
• minimal size: 6x6, maximal size: 24x24 pixels
• only two-color but the whole image can have more colors.

Code:

• Non-cryptic plain code: C, Python, Basic, Fortran and those not too far from it
• hacks (e.g. for old platforms) should be documented somehow and reproducable in theory

Points given for:

• less unique tiles yet with rich possibilities
• visual consistence by each beads type presented, but two types must not necesserily have same style
• Hint: even within one type, the look of one bead can vary but the whole string easily decodable
• interesting scaling possibilities, e.g. parametric scaling
• fullfill the restrictions
• less operations and minimalistic code
• working application, e.g. interactive counter or a micro-game is welcome

Solution publishing:

• title: amount of tiles used and pixel sizes info
• visual examples easy to follow
• notes about interesting sides of solution
• code and some explanation

Sandbox note: If there are unclear point, free to point to corrections. Please suppose better tags if needed.

Tags: code-challengetilinggraphical-outputascii-arttypographybinary

Answer 25

Rainbow Cat Program

code-golf

Recently, I remembered a program I'd written in C# a while back for fun. It takes a string as input, then outputs that same string, cycling through a rainbow of colours. I now realize that this is basically a cat program, but with the added complexity of the output changing colour every 100ms. So I figured it would make an interesting challenge.

The aim is to make your own "rainbow cat program", taking a string as input, and outputting that same string cycling through the following colours in sequence: red, yellow, green, blue, purple, and pink. Not quite a proper rainbow, but close enough. The colours must change every 100ms (or as close to 100ms as your chosen language will allow).

For reference, here's an extremely badly-golfed version of my original C# program (370 bytes):

using System;using System.Threading;class P{static void Main(){var a=Console.ReadLine();for(;;){L(a,ConsoleColor.Red);L(a,ConsoleColor.Yellow);L(a,ConsoleColor.Green);L(a,ConsoleColor.Blue);L(a,ConsoleColor.DarkMagenta);L(a,ConsoleColor.Magenta);}}static void L(string a,ConsoleColor b){Console.Clear();Console.ForegroundColor=b;Console.WriteLine(a);Thread.Sleep(100);}}

And a gif of it in action!

Other Rules

• Trailing whitespace/newlines are allowed; printing so many newlines that you push the text off the screen, then writing it again in the next colour, is not allowed. You must physically clear the screen and rewrite the text rather than writing it out over and over.
• Once the cycle starts, it should continue indefinitely without any user input.
• Standard golfing loopholes apply.
• This is code-golf, so shortest program wins. Feel free to compete for the shortest program in any given language, though: don't feel put off by the golfing languages!

Answer 26

Avoiding Averages

Given a non-empty list of positive integers, reorder the list such that for every pair of indices, the average of the values at those indices is not contained in any index between them.

Rules

• This is code-golf so the shortest code wins.

Work in-progress

Answer 27

Compute the CYK-Table!

code-golfgrammars

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Context-Free Grammars

A context-free grammar is a grammar consisting of rules from one variable to a list of variables and symbols. Every string purely consisting of symbols that can be produced using these rules is said to be accepted by the language. For the purpose of this challenge we're only going to consider grammars in CNF which means that on the right side there's either two variables or one symbol (we're gonna ignore the empty language for this challenge).

The CYK-Algorithm

The CYK-Algorithm is a method to check whether a given word is recognized by a context-free language in CNF. For doing this it iterates over the word and applies all possible rules on all substrings and writes them down in a nice table. This table can then be used to successively find variables generating larger substrings until you (don't) hit the word.

The Input

Your input will be

• A list of strings representing the word
• A list of triples of strings, representing the rules from one variables (the first in the triple) to two variables
• A list of pairs of strings, representing the rules from one variable to a symbol
• A string, representing the starting variable

You may replace the above input format with your favorite input format, as long as you can encode the same amount of information.

The output

The output will be three-dimensional: A list of rows consisting of a list of "candidates" which is a list of strings representing a list of variables. An illustration of this is on Wikipedia.

You may replace the above output format with your favorite output format, as long as you can encode the same amount of information.

Who wins?

This is code-golf so the shortest code in bytes to solve the challenge wins!

Example

Start Symbol: "X"
Word: ["b","a","c","b"]
Rules #1: [("X","X","Y"),("X","Z","Z"),("Y","W","Z"),("Z","X","Y"),("W","Y","W")]
Rules #2: [("X","a"),("Y","a"),("Z","b"),("W","c")]

We're gonna do this step-by-step:

The substrings of length 1 first (this is your first row):

b    , a       , c   , b
["Z"],["X","Y"],["W"],["Z"]

Now for the substrings of length 2 (this is your second row):

[],["W"],["Y"] 

(because there's no way to get ZX or ZY, but W -> YW and Y -> WZ)

Now for the substrings of length 3 (this is your third row):

[],["X","Y","Z"] 

(because there's no rule to get ZW, but X->XY (1+2), Y->WZ (2+1), Z->XY (1+2) where the sum denotes the lengths of of the used substrings)

Finally for the substrings of length 4 (this is your fourth row):

["X"]

(because X->ZZ(1+3))

So in total your final table for this example is gonna look like this:

[
[["Z"],["X","Y"],["W"],["Z"]],
[[],["W"],["Y"]],
[[],["X","Y","Z"]],
[["X"]]
]

where the first index increases as we go downwards, the second increases as we go to the right an dthe third denotes the variable within the "cell".

Answer 28

Physical String Length

Given the following information:

• (String) s - A string to be printed.
• (String) f - The font in which it is to be printed.
• (int) pt - The size of the font in which it is to be printed in pts (no decimals).
  • Note that the input units are in pt (1/72 inch).
  • The output unit should be pixels, rounded to the nearest integer.
  • Use 96 PPI in your conversion.

Output:

• The physical length of the string (how many pixels wide the final string is).

Below are a few examples and a piece of code that will let you test arbitrary combinations.

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import java.awt.Canvas;
import java.awt.Font;
public class F {
    public static void main(String[]args){
        System.out.println(physicalStringLength("What?", "Calibri", 12));
        System.out.println(physicalStringLength("What?", "Calibri", 24));
        System.out.println(physicalStringLength("What?", "Calibri", 36));
        System.out.println(physicalStringLength("What?", "Calibri", 72));
        System.out.println(physicalStringLength("What?", "Helvetica", 12));
        System.out.println(physicalStringLength("What?", "Times New Roman", 12));
        System.out.println(physicalStringLength("What?", "Courier New", 12));
    }

    public static int physicalStringLength(String s, String f, int pt) {
        System.out.print(s + "@[" + f + "," + pt + "]=");
        return new Canvas().getFontMetrics(new Font(f,0,pt)).stringWidth(s);
    }
}

Here's some base-line examples, the output has be created using the above piece of Java code:

What?@[Calibri,12]=35
What?@[Calibri,24]=65
What?@[Calibri,36]=97
What?@[Calibri,72]=193
What?@[Helvetica,12]=35
What?@[Times New Roman,12]=31
What?@[Courier New,12]=35

If you want to see the length of any other strings, use the code provided as a base-line. Using a Java has been banned due to the usage of the example unless you'll be providing a different methodology (kinda sucks, cause Java may be one of the few with a built-in).

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This is code-golf, lowest byte-count wins.

Answer 29

Binary Grids

code-golfrestricted-complexity

Consider the N-dimensional binary grid, with dimensions {d1,d2,...,dN}. Here are a few examples:

6 (N=1): 100101

3x7 (N=2):

1001001
0110110
1001001

3x3x3 (N=3):

010   001   100
100   011   110
011   110   001

What each of these example grids have in common is: they do not contain any consecutive sequences of the same digit longer than 2.

The Challenge

Write a program or function which, given a list of dimensions, outputs the number of binary grid configurations with the given dimensions that satisfy this condition.

Input

A list of positive integers (>1), either via stdin or passed as an argument. Example: 3 2 6, [3,2,6], etc.

Output

The number of valid configurations, either as a returned value or printed to stdout, or something similar.

Constraints

• While brute-force solutions can work, their time complexity is O(2^N), which is way too long for anything but the smallest grids. Write something which will complete before my computer becomes obsolete, please!
• Standard loopholes are forbidden, not that I think very many of them would apply here anyway.
• This is code-golf, so the shortest code wins, with tiebreakers going to the fastest code.

Sandbox Questions

1. Is this interesting?
2. Is this doable?
3. What's a better way to word the time complexity restrictions?
4. The only example for which I actually know the answer is for [6]... do I need more? I'd have to solve this myself first...

Answer 30

Golf Me a Bubble Sort

Your task is to create a program that performs a bubble sort.
For those who don't know, a bubble sort is a simple sorting algorithm where two adjacent items are taken & swapped if they are in the wrong order until all values are in the correct order.

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Rules

1. You must provide an explanation for how your answer does a bubble sort.
2. You may not use built-in or standard library sorting algorithms. You must make your own code.
3. Your program should take a group of numbers as input and output them in the correct order.
   • Input format: 10 5 9 2 . . . (and so on)
   • Output can be an array returned by the program when run.
   • Output can also be the correctly ordered values separated by whitespace.
4. Speed does not matter as much as of the program functions.

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Test Cases

• 10 5 9 2 1 6 8 3 7 4 (you can format it differently depending on your language)
• 1 2 5 4 3

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