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4674 Answers 4674

140 141
143 144

Input part of staff, output its midi.


  • 0-9: octave symbol. Set O = the value.
  • CDEFGAB: a note.
    • If octave is just set, then use the octave.
    • Otherwise, if the distance to last note is larger than 5 (C-A, D-B or C-B),
      • Increase O by 1 if the new note is C or D; decrease if A or B.
    • Output O*12+{C:0, D:2, E:4, F:5, G:7, A:9, B:11}+K[O,c]
  • #, b, ##, bb, %: accidentals. Set K[next note] to 1, -1, 2, -2, 0, respectively.
  • |: bar line. Reset accidentals. (Since beats are not given, bar line doesn't have other meaning.)
  • You can assume all outputs are in [0,127], accidentals appear before octave if both exist, no double octave, octave or accidental to bar line, first note has octave provided

Test cases:

4CCGG|AAG => 48,48,53,53,55,55,53
4CDEFGAB|C4G5C => 48,50,52,53,55,57,59,60,55,60
5E#DEDE4B%DCA => 64,63,64,63,64,59,62,60,57
4C#CFAC => 48,49,53,57,60
#0D#E||##F#G#A#B||##C#D => 3,5,7,8,10,12,14,15
0EDCB => (invalid)
A#|B => (invalid)
10C => (invalid)
#9B => 120
9BCDEFG => 119,120,122,124,125,127
9BCDEFGA => (invalid)

  • Should I have key signatures?
  • Should I shift octave by 1?
  • s and f or # and b?
  • are triple accidentals allowed?
  • \$\begingroup\$ I would keep it simple: note to midi rather than staff to midi to avoid confusing nonmusicians, so no key signatures and no multiple flats/sharps. #`` and b` are used almost universally. That leaves the choice of natural symbol, I would probably go for something nonalphanumeric like ~ or & . I suppose you could keep the bar to reset accidentals to avoid making it too simple. \$\endgroup\$ Mar 24 at 15:09
  • \$\begingroup\$ The octave change needs some thinking about. I would suggest sticking with the standard octave CDEFGAB, although this means octave change when you move between nearby B and C. I appreciate what you're trying to do with your "larger than 5" system but the interval (at least if expressed in letters) needs to be smaller. C to F could be a default up change, and C to G a default down change. C to G is known as a fifth in 1-indexed musical notation, though it's actually only a change of 4 letters in 0- indexed. \$\endgroup\$ Mar 24 at 15:13
  • \$\begingroup\$ @LevelRiverSt I'm recently on Braille Music, where 4th and 5th by default remain in same octave. Lilypond just use the nearest one, though \$\endgroup\$
    – l4m2
    Mar 25 at 2:54

Is the triangle decided?

Given some angles and edges of a triangle, decide if it's decided, impossible or multi possibility.


3 angles and 3 edges. Choose a non-positive value, maybe 0 or non-number, as input to mean not provided. Order is flexible, like [a,b,c,A,B,C], [A,b,C,a,B,c], etc.


3 values, representing decided, impossible or multi possibility.

  • Allow different placeholder for angle and edge?
  • Due to imperfect float, extra condition(AAAS) would likely make it wrongly claim impossible. Suggestion?
  • \$\begingroup\$ I assume that decided means that all the angles and sides are consistent with another, and actually form a Euclidean triangle. Impossible would be the opposite of this. Multi possibility only makes sense if the input is incomplete, i.e. not enough information (angles and edges) to finalise an entire triangle with all sides and angles known. Is that correct? Could you please elaborate what your definition of those three categories are? Also, you have stated that the input is 3 angles and 3 edges. Can it actually be 0-3 angles and 0-3 edges? \$\endgroup\$ Apr 1 at 7:39
  • 1
    \$\begingroup\$ @DanielOnMSE Angles and edges may be missing, which I said maybe (take) 0 or non-number \$\endgroup\$
    – l4m2
    Apr 1 at 8:11

Number houses in a street

House numbering varies across the world, and sometimes within a country, but the traditional numbering system in my country is to have the odd numbers ascending on one side of the street and the even numbers ascending in the same direction on the other side of the street. Here is an example:

9 |
  | 10
  | 8
7 |
5 |
  | 6
  | 4
3 |
1 |
  | 2

Here there are two detached houses, one at each end of the street, and four pairs of semi-detached houses. The empty spaces are probably where the garages and driveways are, but they are not relevant here, so I have left them out.

Your challenge is to write a program or function that will take an unnumbered street and number it.

You can input the houses in any convenient way, so you could take input as a diagram but with the houses marked by a fixed placeholder (e.g. ?), or you could take a pair of lists of distances of each house from the start of the street (so for the above example the input could be [[1, 2, 5, 6, 9], [0, 3, 4, 7, 8]].) Note that there may be two houses directly opposite each other, and there may also be different number of houses on each side of the street.

As well as numbering from the bottom left up, you may also number from the top right down, like this:

 2 |
   | 1
   | 3
 4 |
 6 |
   | 5
   | 7
 8 |
10 |
   | 9

The house numbers on the left of the street must be right-justified and those on the right of the string must be left-justified. The street can be marked with any fixed non-empty non-numeric string of your choice; it doesn't have to be | .

In addition to the above two output formats, I will also allow any rotations (but not transpositions) of the above output formats, in case that is helpful for you, e.g.

 18  64  2
9  75  31


a byte array of length 1 to 31, inclusive.

Take an example, oxDE, 0xAD


Write each byte into 8-bit binary, big-endian 1101111010101101

Average split into 8 parts 11 01 11 10 10 10 11 01

Convert each part from binary to number [3,1,3,2,2,2,3,1]

  • Which endian, or allow both?
  • \$\begingroup\$ @greybeard Title not decided. Average mean with total=m, each given m/8. I say number cuz lots of language at the moment is just number, you need to printf %d to convert it to decimal, or %x hex \$\endgroup\$
    – l4m2
    Apr 1 at 0:31
  • 1
    \$\begingroup\$ Average split -> Evenly split \$\endgroup\$
    – Bubbler
    Apr 1 at 4:33
  • \$\begingroup\$ I don’t understand the question Which endian […]? Endianness is only relevant if multiple bytes together represent one number. In this challenge we have up 31 independent bytes/numbers so endianness is not an issue. \$\endgroup\$ Apr 2 at 10:12
  • \$\begingroup\$ @KaiBurghardt That reverse the array, it seems reasonable to allow both \$\endgroup\$
    – l4m2
    Apr 2 at 10:16
  • \$\begingroup\$ I see. Well, it does not seem “reasonable” to me. Could you explain? I say, KISS – keep it simple. An array element with a lower index comes first, there is no ambiguity in that. \$\endgroup\$ Apr 2 at 10:50

Vending Machine Simulator

Alternate title: Linear Logic Simulator


Write an interactive program that asks you to design a vending machine, and then simulate the vending machine.

The fuss is, the vending machine is designed for simulation of linear logic.


The vending machine has some items available for purchasing, identified by words consisting of ASCII capital Latin letters.

Upon accepting a penny, the vending machine will or will not output an item, owing to its design.

The vending machine's design is defined as a logical expression consisting of the items and the binary operators. The binary operators and their semantics are:

  • P times Q: This vending machine has one slot. Upon accepting a penny, the vending machine will output the items P and Q together.

  • P with Q: This vending machine has two slots. The left slot, upon accepting a penny, will let the machine output P. The right slot, upon accepting a penny, will let the machine output Q.

  • P plus Q: This vending machine has one slot. Upon accepting a penny, the machine has fifty-fifty chance to output P or output Q.

  • P par Q: This vending machine has two slots, and one of them, chosen with fifty-fifty chance, has a pre-installed coin.

    • If you insert a penny in the other slot, the vending machine will consume one of the two pennies with fifty-fifty chance, and will output the item that corresponds to the consumed penny.

    • However, if you insert a penny in the slot that already had a penny pre-installed, the machine will reject the inserted coin, giving it back to you. You will try again with the rejected penny.

I/O format


Worked Examples

Example #1

Design your vending machine: (CANDY with CHIPS) times CHOCOLATE
Simulating (CANDY with CHIPS) times CHOCOLATE...
    Simulating (CANDY with CHIPS)...
        Which slot will you insert a penny? (Left|Right): Left
        Simulating CANDY...
            You get the CANDY.
    Simulating CHOCOLATE...
        You get the CHOCOLATE.

Example #2

Design your vending machine: CANDY par (CHIPS plus CHOCOLATE)
Simulating CANDY par (CHIPS plus CHOCOLATE)...
    Which slot will you insert a penny? (Left|Right): Left
    Wrong guess! The machine rejects the penny.
    Which slot will you insert a penny? (Left|Right): Right
    Correct guess!
    The machine decides to simulate CANDY.
    Simulating CANDY...
        You get the CANDY.

Example #3

Design your vending machine: CANDY par (CHIPS plus CHOCOLATE)
Simulating CANDY par (CHIPS plus CHOCOLATE)...
    Which slot will you insert a penny? (Left|Right): Right
    Correct guess!
    The machine decides to simulate (CHIPS plus CHOCOLATE).
    Simulating (CHIPS plus CHOCOLATE)...
        The machine decides to simulate CHOCOLATE.
        Simulating CHOCOLATE...
            You get the CHOCOLATE.

Meta Question

Any misunderstanding I have? Especially for par?


Rotation by triple skewing

You can rotate a two-dimensional array by an angle by sampling or some other mechanism to approximate the resulting value at a specific point. However this is not very effective for a small array, such as an ASCII-art picture. Instead, we can approximate the rotation by a triple skew.

The first skew shifts the rows of the array by an amount proportional to the distance above or below the centre of rotation. This value is an input which I shall call \$ t \$.

The second skew shifts the columns of the array by an amount \$ \frac{-2t}{1+t^2} \$ multiplied by the distance to the left or right of the centre of rotation.

The third skew is a copy of the first skew.

The shift amounts should be one of rounded, floored or ceilinged so that each row or column is shifted by an integer amount.

The array should be considered to be cyclic so that elements shifted will wrap around to the other side.

Given an input array, a centre of rotation, and \$ t \$, output the resulting rotated array.

The array may be any convenient data type such as bytes, characters or integers. If the array is of characters then you may also represent it as a list of strings.

Example of the three skews for \$t=0.475\$:

  012       012          27DE      27DE 
 34567     34567        16CJK     16CJK 
89ABCDE    89ABCDE     05BIQR     05BIQR
FGH IJK -> FGH IJK -> 34A PVW -> 34A PVW
 STUVW       STUVW    FGNTY       FGNTY 
  XYZ         XYZ     LMSX        LMSX  

This is , so the shortest program that breaks no standard loopholes wins!


Construct the largest number by combining

Given an array, each time you can remove two values \$a\leq b\$, and add value \$\min\left(2a\color{red}{+1},a+b\right)\$.

Return the largest value you can get.

Duplicate Checker

  • The red part is +0 or +1
  • Is it fine to leave some values?
  • \$\begingroup\$ By "Largest value you can get", do you mean: Repeat the function until only 1 value remains, or Return the highest value obtained by a pair in the original list? \$\endgroup\$
    – ATaco
    Apr 4 at 20:52
  • \$\begingroup\$ @ATaco Not decided, ref "Is it fine to leave some values?" \$\endgroup\$
    – l4m2
    Apr 5 at 4:09

Is this function communative?

Given a function of the form of a valid mathematical expression with at least two variables named a through z, determine if it is impossible to rearrange the values of the variables so that the result is different. For example:

$$ x + y - 3 $$

would be commutative, because let's \$x = 2\$ and \$y = 6\$. Then the result would be 33, but even if you made \$x = 6\$ and \$y = 2\$, the result would be the same.


  • The expression consists of digits (0-9), addition (+), subtraction (-), multiplication (*), and division (/). No ab, it will always be written as a * b.
  • You may evaluate the expression left-to-right or adhere to the order of operations, but it must be consistent.
  • Variables can be any positive integer including zero unless that might result in division by zero.

Test cases

x + y - 3 => True
x * 3 / y => False
3 * x + y / x * 0 => True
  • 1
    \$\begingroup\$ Case x/x, x-y+0/0 ? \$\endgroup\$
    – l4m2
    Apr 10 at 1:00
  • \$\begingroup\$ What about x+2 + (y*y - 4) / (y - 2)? \$\endgroup\$ Apr 11 at 8:35
  • 1
    \$\begingroup\$ Do you have a solution? Is this problem always solvable? \$\endgroup\$
    – Tbw
    Apr 12 at 20:54
  • 1
    \$\begingroup\$ Typo in the title. And if the input can't contain parentheses, aren't left to right and order of operations solutions on totally different playing fields? (Maybe allow/encourage looser I/O, like prefix notation or even a pre-parsed tree structure.) \$\endgroup\$ Apr 17 at 2:01
  • 2
    \$\begingroup\$ Test cases with more than two variables would be good. \$\endgroup\$
    – pxeger
    Apr 17 at 10:12
  • \$\begingroup\$ Things to avoid: parsing expressions \$\endgroup\$
    – xnor
    2 days ago

Given a piece of notes, make accidentals clear.

Accidentals include b, % and #. Pitch names include uppercase A to G1. In input, every note is an accidental and a pitch name. Besides, bar lines exist to split bars.

For each note in output,

  • Default1 claims that a note share the recent accidental with same pitch name in this bar, or % if same pitch name never appeared in this bar. If this is false, preserve accidental as-is. Otherwise,
  • Default2 claims that a note share the recent accidental with same pitch name if there are less than 8 notes between it and current note, % otherwise. If this is false, surround the accidental with (). Otherwise, remove the accidental in output.

Test cases:

%C%C%C%C|#C#C#C#C|#C#C#C#C|%C%C%C%C| =>

enter image description here

1 Whether CDEFGAB or ABCDEFG doesn't matter here

Sandbox Notes

  • Any nouns incorrect
  • Name of Default1 and Default2
  • How does this work in real?
  • \$\begingroup\$ I'm pretty sure for default 2 that a note shares the accidental if there is a same note in the same measure, might be wrong. \$\endgroup\$ Apr 11 at 13:41
  • \$\begingroup\$ @LarryBagel Don't quite understand. Example? \$\endgroup\$
    – l4m2
    Apr 11 at 21:30
  • \$\begingroup\$ I mean that if there is a c-sharp in a measure and a normal c after that c-sharp in the same measure, that c will also be sharp. But if that c is in any other measure (without a c accidental preceding it), it's natural. \$\endgroup\$ Apr 12 at 12:34

Compose Two Polynomials


Given two polynomials \$p\$ and \$q\$ with integer coefficients (and with one indeterminate), output their composition \$p \circ q\$.

I/O format


It is assumed that the inputted polynomials have no leading zero coefficients, and the outputted polynomial shall have no leading zero coefficients, either.


Here, the polynomials are represented as lists of coefficients in descending degree of terms.

p(x), q(x), p(q(x))

[], [2,1], []
[1,2], [], []
[1], [1], [1]
[1], [2], [1]
[4,1], [1], [5]
[2,0], [1,2], [2,4]
[1,2], [2,0], [2,2]
[1,0], [3,3,3,-2], [3,3,3,-2]
[1,0,-1], [1,0,-1], [1,0,-2,0,0]
  • \$\begingroup\$ Duplicate? \$\endgroup\$
    – xnor
    2 days ago
  • \$\begingroup\$ @xnor Nevermind; though that question is poorly titled. \$\endgroup\$ yesterday

This is a joint post with https://puzzling.stackexchange.com/questions/126255/dishonest-dungeon-staff

I guess the tags would be something like fastest-algorithm, math, decision-problem, combinatorics.

You are faced with the difficult task to set up a dungeon for adventurers. However you made a deal with the guild: any adventurer brave enough to beat the dungeon and reach the treasure room will be guaranteed to receive some treasure, whatever he or she does. Of course, this goes against your master's rules, and so you will need to be clever about it. Under normal circumstances, the treasure room works as follows:

There are N keys, and M rooms containing one treasure chest each. Every key opens at least one chest, and every chest has at least one key opening it, but you have no control over which keys open which chests. Each adventurer can pick a key, enter one chest room, and attempt to open each chest reachable from that room, with each key in his or her possession. Your plan is to place the keys on keyrings (so that an adventurer that picks a key also gets any other keys on the same keyring), and dig tunnels connecting different chest rooms (so that an adventurer that enters a chest room can also reach any other rooms connected to it via tunnels), so that for every combination of keyring and chest room, there is at least one key on the keyring that can open a chest reachable from that room. Now, if you were unsupervised, you could put all N keys on the same keyring and connect all M rooms to each other, but you are under close surveillance, so you will need to minimize the risk of getting caught. In practice, this means that you will need to ensure the adventurer wins, with the fewest combinations of keys and chest. For example, combining key 1 and key 2 in one key ring and then combining this key ring with key 3 counts for 2 combinations, and the same goes for chests. You don't have all eternity to find a solution. Your procedure should be able to tell you the actions to take in a reasonable time as a function of N and M.

Is there a way you can ensure you fulfill your contract in the minimum number of combinations?

Input : N,M two integers with no dominance.

Output : The minimum number of combinations that satisfies the constraint.

New contributor
Fluorine is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.

Divisibility patterns

I wrote a script to visualize problem spots for code in this question and the output was prettier and more patterny than I expected. Your task in this challenge is to create a similar (generalized) output in as few bytes as possible.


Your inputs are a string and an integer. Your output is the 2d matrix of results achived from adding 0 to N spaces between each character and then deleting 0 to M length segments.

Another way to interpret this is "if given a program meant to solve one 'slice' of the linked question, how would it impact each of the other programs?"


input of 5 abcdefghijklmnopqrstuvwxz, one output per line and matrix columns seperated with an extra newline:

a     f     k     p     u     
a  c  e  g  i  k  m  o  q  s  u  w  z 
a b c d e f g h i j k l m n o p q r s t u v w x z 
a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  z  
a     b     c     d     e     f     g     h     i     j     k     l     m     n     o     p     q     r     s     t     u     v     w     x     z     

a    g    m    s    z
a    e    i    m    q    u    z 
a    d    g    j    m    p    s    v    z 
a    c    e    g    i    k    m    o    q    s    u    w    z  
a    b    c    d    e    f    g    h    i    j    k    l    m    n    o    p    q    r    s    t    u    v    w    x    z    

a d g j m p s v z
a   f   k   p   u   
a   d   g   j   m   p   s   v   z 
a b c d e f g h i j k l m n o p q r s t u v w x z 
a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   z   

a  f  k  p  u  
a  e  i  m  q  u  z
a  c  e  g  i  k  m  o  q  s  u  w  z 
a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  z 
a f k p u 
a d g j m p s v z
a b c d e f g h i j k l m n o p q r s t u v w x z 



Valid programs take one integer and one string input (or equivalent from your language), and output (N+1)^2 strings corrosponding to each combination of N and M. The order the strings are output in does not matter.

@sandbox: is the problem clear/understandable? what other tags would apply? also, how long after posting should I wait before adding the script I golfed? I doubt that sed would be the first language anyone else would want to solve this problem with anyways; I mostly made this becasue I had fun golfing it myself and wanted to see how much better or worse other languages did.


Enumerate all matches of a regex

For this challenge, we'll be using a simplified dialect of regular expressions, where:

  • A lowercase letter from a to z matches itself.
  • (expr1|expr2) matches either of expr1 and expr2. You will not have to handle more than two operands, and you can assume there will always be parentheses around this. Instead of (a|b|c) you'll recieve ((a|b)|c).
  • (expr)* matches zero or more copies of expr. You can assume there will always be parentheses around the expression, i.e. you'll recieve (a)* and not a*.
  • (expr)? matches either nothing or expr. You can assume there will always be parentheses around the expression, i.e. you'll recieve (a)? and not a?.
  • expr1expr2 matches expr1 followed by expr2.

You may instead take the expression as some sort of AST. For example, this would be an acceptable format for the regex (be)*((a)?|(c|d)*), but you can use any reasonable format as long as it doesn't contian any information not present in the original regex. You may assume the expression and all subexpressions are nonempty - ()*, (a|), ()? and similar will never occur in the input.

Your challenge is to, given a simplified regex in this format, output all finite strings that the regex matches. However, there will be (countably) infinitely many strings that are matched, and every single one of them must appear at some finite index in the output. You can assume the regex will have infinitely many potential matches, and your output may contain duplicate strings so long as every string eventually appears.

For example, given (a)*(b)*, your output should contain all strings consisting of zero or more as followed by zero or more bs. Given this regex, outputting , a, aa, aaa, aaaa, aaaaa... (note the empty string) would not be allowed as this output would never include any string containing one or more bs. Outputting , b, a, bb, ab, aa, bbb, abb, aab, aaa, bbbb, abbb, aabb..., however, using Cantor diagonalization to enumerate all possibilities, is fine as it will eventually output every string.

Standard output rules apply - you may output all matches, or take an 0/1-indexed n and output the nth / first n terms. This is , shortest wins!


These are potential sequences of the first 20 terms for the given regex. It's fine if your solution outputs a different sequence as long as it eventually outputs everything.

ab* -> a, ab, abb, abbb, abbbb, abbbbb, abbbbbb, abbbbbbb, abbbbbbbb, abbbbbbbbb, abbbbbbbbbb, abbbbbbbbbbb, abbbbbbbbbbbb, abbbbbbbbbbbbb, abbbbbbbbbbbbbb, abbbbbbbbbbbbbbb, abbbbbbbbbbbbbbbb, abbbbbbbbbbbbbbbbb, abbbbbbbbbbbbbbbbbb, abbbbbbbbbbbbbbbbbbb
a*b* -> , b, a, bb, ab, aa, bbb, abb, aab, aaa, bbbb, abbb, aabb, aaab, aaaa, bbbbb, abbbb, aabbb, aaabb, aaaab
a*c?b*d -> d, cd, bd, cbd, ad, acd, bbd, cbbd, abd, acbd, aad, aacd, bbbd, bbbcd, abbd, acbbd, aabd, aacbd, aaad, aaacd
(a|b)* -> , a, b, ba, bb, baa, bab, bba, bbb, baaa, baab, baba, babb, bbaa, bbab, bbba, bbbb, baaaa, baaab, baaba
(aa*b)* -> , ab, aab, aaab, abab, aaaab, aabab, abaab, aaaaab, aaabab, aabaab, abaaab, ababab, aaaaaab, aaaabab, aaabaab, aabaaab, abaaaab, aababab, abaabab

Consecutive Composites

Your task is to write a program or function which, given a positive integer N, finds the first block of N consecutive composite numbers.

This should be the first block of integers which fit the requirements, larger than 0. For example, with an input of 2, the output must be [8, 9], and not [14, 15].


  • The numbers in the block should be printed or returned as a list, in any reasonable format.
  • Submissions may be either full programs which perform I/O, or functions - no snippets.
  • You can assume that the block of numbers your program has been request to find is within your language's standard integer range.
  • This is , so the shortest program (in bytes) wins! Standard golfing loopholes apply.

Test Cases

1 -> [1]
2 -> [8, 9]
5 -> [24, 25, 26, 27, 28]
6 -> [90, 91, 92, 93, 94, 95]
10 -> [114, 115, 116, 117, 118, 119, 120, 121, 122, 123]

  • 1
    \$\begingroup\$ This is essentially codegolf.stackexchange.com/q/23844/194 with a tweaked output format. \$\endgroup\$ Feb 6, 2017 at 9:34
  • \$\begingroup\$ One is not a composite number, the smallest is four, so the test case for 1 should be [4]. \$\endgroup\$ Feb 6, 2017 at 20:39
  • \$\begingroup\$ @JonathanAllan i've misused the term composite there, I meant 'non-prime' - regardless, I probably won't post this anyway and Peter pointed out it's basically a dupe. \$\endgroup\$
    – FlipTack
    Feb 6, 2017 at 22:02

Wifi Puzzle! Crack the router [code-golf] [networking]


Consider that you have three wifi routers in your home , all with different SSIDs and none of them are dualband. You have invited a mischievous friend to your home who had changed the password of each router, without letting you know about it. Now to annoy you more he has set up a programming challenge.


Your friend has created three .txt files containing a set of passwords with only one correct among them. (i.e. each .txt file contains a correct password while all other are wrong ones. Also one .txt file contains only one correct password) and the .txt files do not specify which one may contain the correct password for a certain router (i.e. you cannot be sure that file1.txt(let us assume it is one of those .txt files) contains the password for router1( say any one of those routers). Now your friend has kept them in a certain directory( say E:\Wifi) and asked you to create a programme or function that would pick up a file and take input from it, try to connect to a random Access point ( out of the three routers) and find which password fits to which router.

Sample Input

Let us consider a file, file1.txt( or any other name you like) be like this


Note that each password contains a capital letter, numbers, special characters, (of a standard keyboard) and each file contains only five unique passwords. Also all the .txt files are in the same directory and there are no subdirectories in the directory concerned. Also each .txt file contains at least one correct password.

Sample Output

Your programme or function must keep a log of its activity in a separate file log.txt which you may put in the same directory concerned or in a different directory. The log file must show which router has been cracked with which password and also the file containing it.

Example: Say that router1 ( SSID of a router) has been cracked by the password A12e77799U5 from file1.txt so the output of the log.txt must be

router1 password A12e77799U5
File: file1.txt

Also you must be sure that all the output goes into the log.txt not seperate files each time a router is cracked. You can create a programme or a function in any programming language.

Keep In Mind

  1. This is code-golf so the shortest answer wins.

  2. Standard loopholes apply as usual.

Discussion I feel to ask this question but the foremost problem I face is how can others test their code. Also strict I/o rules (like the log.txt I mentioned ) are not appreciated here. So please help me out!

  • 1
    \$\begingroup\$ So, you want us to access the network settings programmatically? Even if we disregard the difficulties in testing it, this is not a golfing challenge, but rather a challenge in convincing our OSes to let us fiddle with the settings, and then figuring out how. \$\endgroup\$ Feb 12, 2017 at 19:25
  • \$\begingroup\$ So is there any category I can put it in, I mean any tags. \$\endgroup\$
    – jyoti proy
    Feb 12, 2017 at 20:04

Portable bitmap checkerboard pattern

Your task is to create a checkerboard pattern and store it in a PBM.

Size of the checkerboard is passed in STDIN as two numbers. Output is written to STDOUT.

Test case:


5 5
0 1 0 1 0
1 0 1 0 1
0 1 0 1 0
1 0 1 0 1
0 1 0 1 0

This is so the shortest code wins


Bike saddle drawn through a fractal

Based on the Mandelbrot image in every language, and on the observation the 3rd layer (0 indexed) always looks like a bike saddle, I had a little bit different challenge:

  • Language must be capable of graphical output or drawing charts (saving files disallowed)
  • Render a window or control that is resizable by mouse action. As example, it can be a typical GUI Window with the typical frame that allows resizing
  • After resizing the GUI element, the fractal should be updated according to the new pixel space
  • The fractal coordinates range from approximately -2-2i to 2+2i
  • The pixels outside of the 3rd layer (0 indexed) of Mandelbrot set should have one color; the ones inside 3rd and inner layers should have another. The only two colors used should be clearly distinguishable
  • At least 99 iterations
  • ASCII art not allowed

Winning conditions:
Shortest version (size in bytes) for each language will get a mention in this post, ordered by size.
No answer will ever be 'accepted' with the button.

  • \$\begingroup\$ @Mark Jeronimus: credits to you. \$\endgroup\$
    – sergiol
    May 27, 2017 at 8:48
  • \$\begingroup\$ "The only two colors used should be clearly distinguishable" Clarification? \$\endgroup\$
    – Joao-3
    Aug 15, 2023 at 14:30

Do nothing

Write a program which terminates normally (not in an error), producing no output on the standard output stream (or the language's closest equivalent), nor on the standard error stream, regardless of what content is present on the standard input stream. (Note that this is intentionally overriding the normal I/O defaults; this is a challenge entirely about input/output handling.)

Additionally, your program may not have any other side effects (e.g. writing files, changing persistent state), unless they're an unavoidable consequence of running a program on the operating system you're using (e.g. on Linux, it's OK to change the "next process ID number to be assigned" value inside the kernel, because that happens whenever you run a program).

Finally, to avoid numerous uninteresting 0-byte (or boilerplate-plus-0-byte) solutions, you may not use a language in which the shortest program that does nothing (i.e. complies with the above specification) is also the shortest (or tied for the shortest) program which runs without error (but possibly reacts to input or produces output). In other words, you can't use a language unless doing nothing is more verbose than doing something.


  • Intentionally exiting the program early is permitted. If you do exit the program manually, on a system that uses exit codes, you may do so with any exit code.
  • Crashing the program is not permitted, even if it (for some reason) exits with a "success" code after the crash.
  • "No output" means 0 bytes of output, not even a trailing newline.
  • Likewise, your program must be able to handle any finite sequence of bytes on the standard input stream, even if it isn't, say, made of characters in the current encoding (but rather of arbitrary octets). You do not need to handle infinite input, though (e.g. your program won't be connected to /dev/zero or the like).
  • You don't have to actually read input; it's your choice as to whether you want to read and discard it, or not read it at all.

Victory condition

As a challenge, shorter is better, measured in bytes. (Remember that if you need to run the program in an unusual way, that incurs a byte penalty, under standard PPCG rules.)

Because languages which are particularly suited for this task (such as Perl and Python) are excluded by the rules, there's not much point in talking about the best answer cross-language; rather, the aim is to find the best answer you can in the language which you submit in. (Historically, on this sort of challenge, answers that are more unusual, interesting, or better-explained have tended to get more votes.)

Sandbox questions

Is this too trivial? We were discussing it in chat as a joke, and realised that it's actually possibly more interesting than it sounds. I'm fairly sure the spec's correct (although would definitely appreciate knowing if something's wrong here!), but would appreciate feedback on how much people would hate me if I posted it to main.

  • \$\begingroup\$ you can't use a language unless doing nothing is more verbose than doing something.you can't use a program unless your program is more verbose than any other program which does something. You must provide a shorter program which does something to prove your solutions validity. \$\endgroup\$
    – Adám
    Jun 8, 2017 at 1:03
  • \$\begingroup\$ @Adám: If you did that, people would just add a comment byte or two to create a program of the shortest possible length that was longer than a program that did something. That isn't particularly interesting. \$\endgroup\$
    – user62131
    Jun 8, 2017 at 1:21
  • \$\begingroup\$ So I write a buffer null that accepts input stdin > /dev/null I think it should do nothing. If it produces Moby Dick I will be surprised. \$\endgroup\$
    – Willtech
    Dec 28, 2023 at 8:23

Plan and Chain a route through OEIS

Your Task is to reach so many OEIS sequences you could make with chaining your last sequence with a operation to a new sequence.

You must avoid last sequence minus last sequence plus first sequence or something similar that your new sequence is based on the first sequence except to make the second sequence.

Your starting OEIS sequence is in every case https://oeis.org/A001477

Given as Input an positive Integer and a Letter that matches [A-Z] or [a-Z]


PHP, 171 bytes


Try it online!

The example gives back the n value of a OEIS sequence for the following letters. A letter greater h is for this example a invalid input

  • a https://oeis.org/A001477 numbers
    $a Valid first sequence

  • b https://oeis.org/A000035 mod 2
    $b=$a&1 Valid use the variable in the sequence before

  • c https://oeis.org/A109613 odd numbers
    $c=$a+!$b Valid Can use sequences before

  • d https://oeis.org/A110654 a(n) = floor(n/2) + n mod 2
    $d=(($c-!$b)/2^0)+$b Valid an invalid example is $d=(($a/2)^0)+$b cause it not use the sequence before

  • e https://oeis.org/A000217 triangular
    $A[$b]=$e=$d*$c Valid you can create help variables

  • f https://oeis.org/A000290 square
    $f=$e+$A[!$b] Valid use a help variabale and the variable of the sequence before. $f=$A[!$b]+$A[!$b] Invalid causes it makes the same value but use indirectly the variable of the sequence before

  • g https://oeis.org/A000142 factorial $g=$a?$g*sqrt($f):1 Valid cause your condition is not always the case that it have no relationship to the sequence before.

  • h https://oeis.org/A019590 Fermat's Last Theorem $h=$g%2 Valid but now we have the problem to find the next sequence

Could You make a full alphabet? My alphabet ends with the letter h

  • \$\begingroup\$ I'm rather confused as to what is being asked here. It might be helpful to state how one can get from one sequence to another. \$\endgroup\$
    – Wheat Wizard Mod
    Jun 10, 2017 at 20:47
  • \$\begingroup\$ @WheatWizard I could understand you. The problem is at the moment to make rules that avoid that a trivial solution exits. There are too many sequences in OEIS. The way from every sequence to the next should not end in a simple addition or multiplication. But evrything else should be allowed to get more creative solutions \$\endgroup\$ Jun 10, 2017 at 20:56
  • \$\begingroup\$ (1) The first sentence says that the aim is to build the longest chain possible, but the scoring mechanism rewards average code length per element in the chain rather than number of chains. I would think it most likely as it stands that the winner would be a chain of length 1 or at most 2. (2) If you delete everything from the header Example to the end, do you think that the question still makes sense? If not (and I don't think it does), it needs a lot of work. (3) What do the two values in the input mean? Why is the second one a letter rather than a number? \$\endgroup\$ Jun 10, 2017 at 21:10
  • \$\begingroup\$ (4) I'm not sure how feasible it is to write objective rules which forbid "trivial" expressions. (5) It is not clear how to interpret the rule about the 32nd term where either it is not known or the sequence is finite and shorter than 32 terms. \$\endgroup\$ Jun 10, 2017 at 21:12
  • \$\begingroup\$ @PeterTaylor (1) Think you that popularity Contest is a better winning criteria? (2+3) to limit the chaining length to 26. The goal is to show relationsships between two or more sequences. (4+5) Yes it is not easy and I can drop it if I switch to popularity Contest \$\endgroup\$ Jun 10, 2017 at 21:26
  • \$\begingroup\$ @WheatWizard I allow now trivial solutions \$\endgroup\$ Jun 10, 2017 at 21:53
  • \$\begingroup\$ I'm not clear on the purpose of the inputs if we're just supposed to hard code our way from one sequence to the next​. Replacing your PHP example with more generic, more verbose pseudo-code might help. \$\endgroup\$
    – Shaggy
    Jun 11, 2017 at 0:16
  • \$\begingroup\$ @programmer5000 exists a limit of correct tags? \$\endgroup\$ Jun 11, 2017 at 11:39
  • \$\begingroup\$ @Shaggy See it as restriction for ways to code. You must have a chaining to the sequence before. So far I know any working code is a pseudocode \$\endgroup\$ Jun 11, 2017 at 11:48

Braid Badly Boundlessly

Your program or function must, given a string in any standard input format, output an infinite stream of delimiter-separated strings where each string is determined from the previous by a braiding algorithm. The program starts with printing the input string.

The algorithm is described as follows: Infinitely alternate between

(1) splitting the string into three substrings then swapping the first two substrings and flattening.


(2) splitting the string into three substrings then swapping the last two substrings and flattening.

starting with (1).

The three substrings should be of non-increasing length with the maximum length no more than 1 greater than the minimum length of the three substrings. (This means that when the length of the given string is a multiple of three, the three substrings should be the same length. When the length of the given string is one more than a multiple of three, the first substring should be one character longer than each of the last two substrings. When the length of the given string is two more than a multiple of three, the first and second substrings should each be one character longer than the last substring.)


Let the input be "abcdefg". Let the delimiter be a newline.

Then the program would first print "abcdefg".

It applies (1) which splits the string into ["abc","de","fg"] and swaps the first two elements, reaching ["de","abc","fg"]. It flattens to get "deabcfg" which it prints and uses for the next step.

The program applies (2) to "deabcfg" to split into ["dea","bc","fg"] and swaps into ["dea","fg","bc"], flattening to reach "deafgbc".

The program applies (1) to "deafgbc" and the process repeats ad infinitum.

Then the output would be the newline-separated



  • Note that the string should not be split at the beginning and then only swapped later. The string should be split on each and every iteration
  • The delimiter between lines could be whichever character is convenient. You may assume it does not appear in the input string.
  • The string input shall be at least three characters
  • The input consists solely of printable characters (0x20-0x7F)
  • Of course, standard loopholes are forbidden.


  • The input and output should be taken in standard I/O methods.
  • The input and output should be taken as string, list of characters, or equivalent.
  • The output should be output continuously, which means you may assume infinite memory.

Test cases

For the test cases, we will assume that the delimiter is a newline. Just the portion before the endless stream is repeats is shown.

O Canada!
O Canada!
anaO Cda!
anada!O C
da!anaO C
da!O Cana
O Cda!ana
A man, a plan, a canal - panama!
A man, a plan, a canal - panama!
an, a canalA man, a pl - panama!
an, a canal - panama!A man, a pl
 - panama!Aan, a canal man, a pl
 - panama!A man, a plan, a canal
 man, a pla - panama!An, a canal
 man, a plan, a canal - panama!A
n, a canal  man, a pla- panama!A
n, a canal - panama!A man, a pla
- panama!A n, a canal man, a pla
- panama!A man, a plan, a canal 
man, a plan- panama!A , a canal 
man, a plan, a canal - panama!A 
, a canal -man, a plan panama!A 
, a canal - panama!A man, a plan
 panama!A m, a canal -an, a plan
 panama!A man, a plan, a canal -
an, a plan, panama!A m a canal -
an, a plan, a canal - panama!A m
 a canal - an, a plan,panama!A m
 a canal - panama!A man, a plan,
panama!A ma a canal - n, a plan,
panama!A man, a plan, a canal - 
n, a plan, panama!A maa canal - 
n, a plan, a canal - panama!A ma
a canal - pn, a plan, anama!A ma
a canal - panama!A man, a plan, 
anama!A mana canal - p, a plan, 
anama!A man, a plan, a canal - p
, a plan, aanama!A man canal - p
, a plan, a canal - panama!A man
 canal - pa, a plan, anama!A man
 canal - panama!A man, a plan, a
nama!A man, canal - pa a plan, a
nama!A man, a plan, a canal - pa
 a plan, a nama!A man,canal - pa
 a plan, a canal - panama!A man,
canal - pan a plan, a ama!A man,
canal - panama!A man, a plan, a 
ama!A man, canal - pana plan, a 
ama!A man, a plan, a canal - pan
a plan, a cama!A man, anal - pan
a plan, a canal - panama!A man, 
anal - panaa plan, a cma!A man, 
anal - panama!A man, a plan, a c
ma!A man, aanal - pana plan, a c
ma!A man, a plan, a canal - pana
 plan, a cama!A man, anal - pana
 plan, a canal - panama!A man, a
nal - panam plan, a caa!A man, a
nal - panama!A man, a plan, a ca
a!A man, a nal - panamplan, a ca
a!A man, a plan, a canal - panam
plan, a cana!A man, a al - panam
plan, a canal - panama!A man, a 
al - panamaplan, a can!A man, a 
al - panama!A man, a plan, a can
!A man, a pal - panamalan, a can
!A man, a plan, a canal - panama
lan, a cana!A man, a pl - panama
lan, a canal - panama!A man, a p
l - panama!lan, a canaA man, a p
l - panama!A man, a plan, a cana
A man, a pll - panama!an, a cana

Quick! Tell me all the numbers from 1 to 100,000!

Your task is to write a program or function that, when run, output all the numbers from 1 to 100 thousand as quickly as possible to STDOUT. It's that simple. All answers are tested on an HP Compaq nx9420 with an Intel Core Duo @ 1.83 GHz and 3 gigs of RAM using the time command.

Of course, standard loopholes are strictly forbidden.
This is , so may the fastest code win and the best programmer prosper...

  • 3
    \$\begingroup\$ Have you tried running an example to see if the times are variable enough to be meaningful? As-is, this is going to be strongly dependent upon how fast the code can do I/O, which makes the challenge pretty uninteresting, IMO. \$\endgroup\$ Jul 19, 2017 at 18:16
  • \$\begingroup\$ @AdmBorkBork Might be interesting \$\endgroup\$
    – ckjbgames
    Jul 19, 2017 at 21:12
  • 1
    \$\begingroup\$ As far as I can tell, this takes less than a tenth of a second, which means submissions will probably be differentiated solely by noise on your computer. \$\endgroup\$ Jul 20, 2017 at 2:37
  • \$\begingroup\$ upvoted, though I think the differenciation is really difficult, unless you test it on a raspberry PI (for example) having ONLY the program and its compiler installed. \$\endgroup\$ Jul 20, 2017 at 13:36
  • \$\begingroup\$ @FryAmTheEggman How could I improve on that? \$\endgroup\$
    – ckjbgames
    Jul 20, 2017 at 23:38
  • 1
    \$\begingroup\$ @V.Courtois I do have a Pi, and I think I will use that (it has Raspbian installed). \$\endgroup\$
    – ckjbgames
    Jul 20, 2017 at 23:39
  • \$\begingroup\$ The time is still so small even a basic operating system will have to much noise in process creation, etc, for this to work out. You need to make what we are computing substantially more complicated for this to be reasonable. \$\endgroup\$ Jul 21, 2017 at 0:10
  • \$\begingroup\$ @FryAmTheEggman K \$\endgroup\$
    – ckjbgames
    Jul 21, 2017 at 1:20
  • \$\begingroup\$ @ckjbgames good then :) \$\endgroup\$ Jul 21, 2017 at 5:26

What's that character? (Part 1)

Recently I ran a command on my laptop that returned a bunch of characters - some printable, some non-printable. I'm having trouble figuring out what those characters are, so I could use some help. Unfortunately, I'm running low on disk space, so you'll have to write me the shortest program you can that I can run.


Given a list of ASCII characters, return their names as written on www.asciitable.com, my go-to site for looking up character points.


You may take a string, a list of characters, or a list of ASCII code points (e.g. 'a' -> 97).

You may optionally take the length of the string/list as well. Note that for C, you must take this parameter, since the string could contain NUL bytes, so strlen won't work here.


Output is flexible as usual; you may print or return from a function as you see fit. You should output a list of strings.

The Table

8 BS
10 LF
11 VT
12 FF
13 CR
14 SO
15 SI
16 DLE
17 DC1
18 DC2
19 DC3
20 DC4
21 NAK
22 SYN
23 ETB
24 CAN
25 EM
26 SUB
27 ESC
28 FS
29 GS
30 RS
31 US
32 Space
33 !
34 "
35 #
36 $
37 %
38 &
39 '
40 (
41 )
42 *
43 +
44 ,
45 -
46 .
47 /
48 0
49 1
50 2
51 3
52 4
53 5
54 6
55 7
56 8
57 9
58 :
59 ;
63 ?
64 @
65 A
66 B
67 C
68 D
69 E
70 F
71 G
72 H
73 I
74 J
75 K
76 L
77 M
78 N
79 O
80 P
81 Q
82 R
83 S
84 T
85 U
86 V
87 W
88 X
89 Y
90 Z
91 [
92 \
93 ]
94 ^
95 _
96 `
97 a
98 b
99 c
100 d
101 e
102 f
103 g
104 h
105 i
106 j
107 k
108 l
109 m
110 n
111 o
112 p
113 q
114 r
115 s
116 t
117 u
118 v
119 w
120 x
121 y
122 z
123 {
124 |
125 }
126 ~
127 DEL

Test Cases

[0, 97, 7, 22] -> [NUL, a, BEL, SYN]

More to come...


  • Would it be more interesting to use the UTF-8 names for the printable characters (0x20 - 0x7E), and the ASCII names for the control characters?
  • \$\begingroup\$ hand copy the table from the website please dont. Try a Google search: theasciicode.com.ar/ascii-codes.txt \$\endgroup\$
    – Stephen
    Jul 23, 2017 at 22:39
  • \$\begingroup\$ @StepHen good call, thanks \$\endgroup\$ Jul 23, 2017 at 23:24
  • \$\begingroup\$ Downvoter: I would much like your feedback rather than just your vote \$\endgroup\$ Jul 24, 2017 at 1:39
  • 1
    \$\begingroup\$ IMO just have take a letter and output the code. Since that part is boilerplate str.chars.map( real program ). Also for ASCII char names NUL is it ok is we output them in lower case? e.g. nul (obviously ascii letters would have fixed case) \$\endgroup\$
    – Downgoat
    Jul 24, 2017 at 1:42

Lennyface parser and selector

Your mission

Create, in the language of your choice, a program that outputs a randomly selected lennyface (artistic minifigures, see this) from an input - a string composed of numbers and lennyfaces. You will have to : first, parse this input; second, extract a probability mass function f from the parsed input; third, select and output a lennyface respecting f. Read the rules for more details.


  • Input : A string with lennyfaces and numbers (positive AND negative integers), separated by newlines. You may take input by STDIN or function parameter for example.
  • Output (STDOUT for example) : the randomly-selected lennyface, as a string.
  • The input creates a probability mass function f. If l is a lennyface, then f(l)=(sum of all numbers since the previous lennyface)/x where x is obtained afterwards by summing each of those numerators. @Sandbox : is it clear enough?
  • If (sum of all numbers since the previous lennyface) is equal to zero or negative, you must do as if the numerator is equal to 1 in f's definition.
  • A line with a number contains only this number ; same for a line with a lennyface. So you can assume there will never be a number in a lennyface.
  • If there is nothing on a line (two newlines in a row), you must consider it as a lennyface.
  • You must consider that the last line of the string is directly before its first line. See Test 1 for an example.
  • You can assume there will be at least 1 lennyface in the list; it cannot be composed just by numbers (don't forget that an empty line is a lennyface too).


Given this input list :

( ͡° ͜ʖ ͡°)


You must have 1/42 chances of outputting ( ͡° ͜ʖ ͡°), 2/42 chances of outputting ¯\_ツ_/¯, 38/42 chances of outputting └[⸟‿⸟]┘ and 1/42 chances of outputting nothing (line 7).

Test cases

Test 1


Must output (⌐■_■) with 3/3 chances.

Test 2


Must output ʢ◉ᴥ◉ʡ with 1/1 chance.

Test 3


Must output \(ᗝ)/ with 1/1 chance.

Test 4

( ͡° ͜ʖ ͡°)
☞   ͜ʖ  ☞


Must output ( ͡° ͜ʖ ͡°) with 1/42 chance, ¯\_ツ_/¯ with 1/21 chance, ☞  ͜ʖ  ☞ with 19/21 chances and nothing with 1/42 chance.

Test 5


( ͡° ͜ʖ ͡°)

Must output ( ͡° ͜ʖ ͡°) with 1/4 chance and nothing with 3/4 chance, since there are 3 empty lines.

Test 6


( ͡° ͜ʖ ͡°)

Must output nothing with 43/44 chance and ( ͡° ͜ʖ ͡°) with 1/44 chance.

@Sandbox : should I add test cases?

This is , so shortest code in bytes wins. Standard loopholes apply.

Note : Please do not be discouraged if the parsing is difficult to handle in your language, or if testing is hard because of randomness. Your solution might be very interesting algorithmically, not obviously in terms of golfing. Just please explain in your answer why it works.

Moreover, this is the first code-golf I create, so please let me know if something is not appropriate or if I should give more details on a point. And overall, if you downvote, explain me why so I can improve it.

  • \$\begingroup\$ Yours tests seems a bit contraditory. The number is the chance of the next face (line), so what's the point of the empty line in the example / test 4? By the same logic, the test1 should have a 3/4 of outputting nothing? What is the point of the 0 in the test 4? \$\endgroup\$
    – Rod
    Jul 3, 2017 at 14:03
  • \$\begingroup\$ Why is the chance of outputting ( ͡° ͜ʖ ͡°) 1/42 and not 0 ? (since there are no numbers above it) \$\endgroup\$
    – Dada
    Jul 3, 2017 at 14:04
  • \$\begingroup\$ Sorry ! I forgot to copy paste the fact that the minimal chance is 1! \$\endgroup\$ Jul 3, 2017 at 14:05
  • \$\begingroup\$ Also, a common thing to do on challenges involving randomness, and therefore, hard to test, is to ask people to provide a mandatory explanation, or at least ask them to show why it works. \$\endgroup\$
    – Dada
    Jul 3, 2017 at 14:05
  • \$\begingroup\$ @Dada thanks. I note this. \$\endgroup\$ Jul 3, 2017 at 14:06
  • \$\begingroup\$ @Rod the empty line is a lennyface, as said here : If there is nothing on a line, you must consider it as a lennyface. \$\endgroup\$ Jul 3, 2017 at 14:08
  • \$\begingroup\$ @V.Courtois I meant and empty line without a preceding number \$\endgroup\$
    – Rod
    Jul 3, 2017 at 14:09
  • \$\begingroup\$ As I said, the minimum is one (sorry again for forgetting it). \$\endgroup\$ Jul 3, 2017 at 14:10
  • 1
    \$\begingroup\$ If only positive integers are to be expected, you should write it. Otherwise, give some details and examples about what you consider "numbers". \$\endgroup\$
    – Dada
    Jul 3, 2017 at 14:12
  • \$\begingroup\$ @Dada editing. In fact I said the minimum is 1, but you can have things like 2,-1,-3,17 and then your lennyface ; that means the probability is 15/ total. \$\endgroup\$ Jul 3, 2017 at 14:14
  • \$\begingroup\$ @V.Courtois just a small suggestion, to make the "list as circle" more explicit you could change the value to something else than 0 or 1, this way it would not overlap the "missing number" rule \$\endgroup\$
    – Rod
    Jul 3, 2017 at 14:15
  • \$\begingroup\$ @Rod does it? Sorry if I'm not getting what you are saying, but the list is always a circle, meaning if your list is 2,3,( ͡° ͜ʖ ͡°),4,5,☞  ͜ʖ  ☞,6, you have 6+2+3 chance of getting ( ͡° ͜ʖ ͡°) and 4+5 chance of getting ☞  ͜ʖ  ☞. \$\endgroup\$ Jul 3, 2017 at 14:18
  • \$\begingroup\$ thanks for editing @musicman523 \$\endgroup\$ Jul 4, 2017 at 7:21
  • 5
    \$\begingroup\$ KISS. This is far more complicated than common sense would require. Deliberately overcomplicating things to make it "more difficult" is a guaranteed method to make a bad question. \$\endgroup\$ Jul 4, 2017 at 7:32
  • 1
    \$\begingroup\$ The challenge has two parts as far as I can tell. a) Create a probability mass function from an input by parsing b) sample from the probability mass function. Part a) needs to be rewritten as it is at best ambiguous and at worst just incorrect. \$\endgroup\$
    – user9206
    Jul 5, 2017 at 7:50

Golf Cubically code

Your task is to optimize Cubically source code using one or more optimizations in this post.

How this challenge works:

  • You will choose one or more optimizations below and write a program (in the language of your choice) that performs those optimizations on a Cubically program.
  • Your program will take a Cubically program as input using any allowed input methods, and output a Cubically program using any allowed output methods.
  • The first answer to successfully perform all optimizations wins!


1. Face turn arguments

Before a face turn is performed, the interpreter calculates turns = turns mod 4. So R5 would be equivalent to R1 which is equivalent to R, R7 is equivalent to R3 which is equivalent to R', etc. Also note that R11111 is equivalent to R5, and R22 is equivalent to nothing at all.

Performing this optimization will mean evaluating all arguments to an R, L, U, D, M, E, or S command and shortening them as much as possible.

Test cases:

Relevant code -> Optimization
R11           -> R2
R1            -> R
L33           -> L2
U22           ->
D222          -> D2
M11111        -> M
E00001        -> E
S9            -> S

2. Repeated face turn

When multiple calls to the same face turn command are present right next to each other, they can clearly be golfed. For example, R2R1 is equivalent to R3. UUU is equivalent to U3. F2F2F2F2 is equivalent F8.

Test cases:

Relevant code -> optimization
R2R2R2        -> R6            (R2 if you also choose optimization 1)
LLL           -> L3
UU            -> UU or U2
D3D2D1        -> D6            (D2 if you also choose optimization 1)

3. "Set notepad to" commands

There are some commands that, instead of adding to/subtracting from/multiplying by/dividing by the notepad, just assign to it. Here are all such commands:


When called with multiple arguments, since each argument calls the command separately, only the final argument is relevant. So =123 is equivalent to =3, _00000 is equivalent to _0, and :12345678987654321 is equivalent to 1.

Test cases:

Relevant code -> Optimization
_333          -> _3
=12321        -> =1
+54321        -> +54321
:55           -> :5
/55           -> /55

4. Repeated non-face-turn commands

When multiple face turn commands are present right by each other, their arguments can simply be added together. Commands do not act this way. While R2 calls R with 2, =2 calls = with the face sum of the front face (face index 2).

To perform this optimization, when multiple commands outside of RLUDFBMES appear next to each other, simply remove the duplicated commands without removing the arguments.

Relevant code -> Optimization
_1_1_1_1      -> _1111         (_1 if you also choose optimization 3)
%11%22%33     -> %112233       (%3 if you also choose optimization 3)
+12345+67+8   -> +12345678

5. Nonexistent commands

Go check out the Cubically commands page and you'll see that there are plenty of characters that are not commands. For example, there are no commands that are lowercase letters.

To perform this optimization, remove all nonexistent commands and their arguments from the Cubically source. If the commands also have arguments, you must remove the arguments so that they are not passed to the previous command.

Test cases:

Relevant code -> Optimization
moo cow moo   -> 
moo2cow2moo   -> 
misteR2 FOO   -> R2F
FEAR ME.      -> ERME
u1U2u3U4u5U6  -> U2U4U6   (nothing if you also choose optimization 1, U12 if you also choose optimization 2)

6. Non-implicit commands

There are lots of implicit commands in Cubically (RLUDFBMES()$~&E!), but there are plenty that need to be called with arguments. So %%%% is equivalent to nothing at all while %%2%% is equivalent to %2.

Test cases:

Relevant code -> Optimization
%%%%          -> 
$$$$          -> $$$$
++2++2++2     -> +2+2+2                 (+222 if you also choose optimization 4)
+++>--<-      -> Not Brainf**k, sorry!  (:P)


I'll add more optimizations later.

  • \$\begingroup\$ Clarification on R123: That's the same as R6 and R2, not R3, right? Digits are summed, there are multidigit numbers? That would be better to specify \$\endgroup\$
    – isaacg
    Aug 17, 2017 at 20:13
  • \$\begingroup\$ A few things: first, I can't find the tag "fgitw", is there a typo? Second, does optimization 1 require handling F and B as well, or just the currently listed ones? Third, in optimization 3 most of the listed commands seem invalid because the notepad is used in calculation and then overwritten with the output; for example =11 is not the same as =1 in most circumstances. In fact, I think only _: are valid. Fourth, is the winning answer one which performs all optimizations in a single program, or one which contains a separate program for each optimization? \$\endgroup\$ Aug 18, 2017 at 18:03

Hungry for Apples?

enter image description here

This challenge is simple, given an integer 0 <= n or 0 < n, output an ASCII-apple with that many bites taken out of it.

No bites (0):

   .'   ''   '.
   ;          ;
  :            :
  :            :
  :            :
   :          ;
   '.        :

Bite 1:

   .'   ''   '.
   ;          ;
   '-.         :
     }         :
   .-'         :
   :          ;
   '.        :

Bite 2:

   .'   ''   '.
   '-.        ;
     }         :
     }         :
     }         :
   .-'        ;
   '.        :

Bite 3:

   .'   ''   '.
   '-.        ;
     }      .-'
     }      {
     }      '-.
   .-'        ;
   '.        :

Bite 4:

   .'   ''   '.
   '-.      .-'
     }      {
     }      {
     }      {
   .-'      '.
   '.        :

Bite 5:

   .'   ''   '.
   '-.      .-'
     }".    {
     } }    {
     } }    {
   .-'"     '.
   '.        :

Bite 6:

   .'   ''   '.
   '-.      .-'
     }"~".  {
     } } }  {
     } } }  {
   .-'"~"   '.
   '.        :

Bite 7:

   .'   ''   '.
   '-.      .-'
     } } } }{
     } } } }{
   .-'"~"~" '.
   '.        :

Bite >7:

[empty output]


  • You may have trailing spaces, make it consistent though.
  • You may have exactly 1 trailing newline.
  • You are NOT doing an animation here, you are taking in n and outputting an apple.
  • You may error on integers less than 0, as the spec provides n > 0.
  • You must have empty output (no error) on n > 7/8.
    • You threw out the core; you didn't error the core into non-existence.

This is

  • 3
    \$\begingroup\$ I feel this would be better if there was some more symmetry in the 5, 6, and 7 bytes so that people could possibly make better compression. \$\endgroup\$ Aug 4, 2017 at 18:26
  • \$\begingroup\$ @AdmBorkBork better? \$\endgroup\$ Aug 22, 2017 at 21:26
  • 1
    \$\begingroup\$ Yes, much better. \$\endgroup\$ Aug 23, 2017 at 12:33

Proper Kerning

Kerning is the adjustment of spacing between pairs of letters in order to obtain an aesthetic result. When kerning is applied automatically by a program (typically whatever editor you're using), it is said to be automatic. There are two types of automatic kerning. The one used in this challenge is metric kerning. With metric kerning, the amount of space between pairs of letters is dictated by the kerning tables found in the font file.

Given a TrueType font file, output the kerning values for each mapping in the kerning table for ASCII characters 48 - 122 inclusive.



l="A" r="C" v="-15"
l="A" r="G" v="-15"
l="A" r="J" v="23"
l="A" r="O" v="-23"
l="A" r="Q" v="-23"
l="A" r="T" v="-160"
l="A" r="U" v="-32"
l="A" r="V" v="-89"
l="A" r="W" v="-80"
l="A" r="Y" v="-150"
l="A" r="t" v="-52"
l="A" r="v" v="-38"
l="A" r="y" v="-41"
l="A" r="?" v="-68"
l="B" r="A" v="-20"
l="B" r="T" v="-48"
l="B" r="V" v="-25"
l="B" r="W" v="-24"
l="B" r="X" v="-44"
l="B" r="Y" v="-57"
l="B" r="Z" v="-20"
l="B" r="f" v="-20"
l="B" r="t" v="-20"
l="B" r="v" v="-20"
l="B" r="x" v="-15"
l="B" r="y" v="-20"
l="C" r="G" v="-18"
l="C" r="J" v="12"
l="C" r="O" v="-18"
l="C" r="Q" v="-18"
l="C" r="T" v="10"
l="D" r="A" v="-30"
l="D" r="J" v="-22"
l="D" r="T" v="-23"
l="D" r="V" v="-24"
l="D" r="W" v="-14"
l="D" r="X" v="-31"
l="D" r="Y" v="-39"
l="D" r="Z" v="-22"
l="E" r="A" v="-22"
l="E" r="C" v="-24"
l="E" r="G" v="-24"
l="E" r="O" v="-32"
l="E" r="Q" v="-32"
l="E" r="S" v="-20"
l="E" r="Z" v="-10"
l="E" r="a" v="-34"
l="E" r="c" v="-28"
l="E" r="d" v="-30"
l="E" r="e" v="-37"
l="E" r="f" v="-64"
l="E" r="o" v="-37"
l="E" r="q" v="-30"
l="E" r="t" v="-24"
l="E" r="v" v="-48"
l="E" r="w" v="-34"
l="E" r="y" v="-48"
l="F" r="A" v="-115"
l="F" r="C" v="-18"
l="F" r="G" v="-18"
l="F" r="J" v="-109"
l="F" r="O" v="-18"
l="F" r="Q" v="-18"
l="F" r="S" v="-29"
l="F" r="X" v="-22"
l="F" r="Z" v="-11"
l="F" r="a" v="-55"
l="F" r="c" v="-28"
l="F" r="d" v="-20"
l="F" r="e" v="-30"
l="F" r="o" v="-28"
l="F" r="q" v="-20"
l="F" r="s" v="-35"
l="G" r="T" v="-10"
l="G" r="V" v="-10"
l="G" r="W" v="-9"
l="G" r="Y" v="-30"
l="G" r="v" v="-29"
l="G" r="w" v="-22"
l="G" r="x" v="-14"
l="G" r="y" v="-30"
l="J" r="A" v="-35"
l="J" r="X" v="-20"
l="K" r="C" v="-78"
l="K" r="G" v="-80"
l="K" r="O" v="-97"
l="K" r="Q" v="-97"
l="K" r="S" v="-18"
l="K" r="U" v="-29"
l="K" r="W" v="-34"
l="K" r="a" v="-34"
l="K" r="c" v="-40"
l="K" r="d" v="-33"
l="K" r="e" v="-37"
l="K" r="f" v="-25"
l="K" r="m" v="-32"
l="K" r="n" v="-32"
l="K" r="o" v="-37"
l="K" r="p" v="-32"
l="K" r="q" v="-33"
l="K" r="r" v="-32"
l="K" r="s" v="-18"
l="K" r="t" v="-38"
l="K" r="u" v="-32"
l="K" r="v" v="-101"
l="K" r="w" v="-95"
l="K" r="y" v="-85"
l="L" r="C" v="-22"
l="L" r="G" v="-47"
l="L" r="J" v="25"
l="L" r="O" v="-45"
l="L" r="Q" v="-45"
l="L" r="T" v="-150"
l="L" r="U" v="-44"
l="L" r="V" v="-147"
l="L" r="W" v="-118"
l="L" r="Y" v="-167"
l="L" r="f" v="-23"
l="L" r="t" v="-38"
l="L" r="v" v="-78"
l="L" r="w" v="-72"
l="L" r="y" v="-79"
l="O" r="A" v="-23"
l="O" r="J" v="-27"
l="O" r="T" v="-55"
l="O" r="V" v="-25"
l="O" r="W" v="-22"
l="O" r="X" v="-64"
l="O" r="Y" v="-55"
l="O" r="Z" v="-38"
l="O" r="x" v="-12"
l="O" r="z" v="-10"
l="P" r="A" v="-151"
l="P" r="J" v="-140"
l="P" r="T" v="-9"
l="P" r="V" v="-10"
l="P" r="X" v="-35"
l="P" r="Y" v="-11"
l="P" r="Z" v="-29"
l="P" r="a" v="-44"
l="P" r="c" v="-43"
l="P" r="d" v="-34"
l="P" r="e" v="-41"
l="P" r="f" v="12"
l="P" r="o" v="-41"
l="P" r="q" v="-34"
l="P" r="s" v="-32"
l="P" r="t" v="12"
l="P" r="y" v="12"
l="Q" r="J" v="41"
l="Q" r="T" v="-47"
l="Q" r="V" v="-25"
l="Q" r="W" v="-12"
l="Q" r="X" v="12"
l="Q" r="Y" v="-46"
l="Q" r="g" v="59"
l="Q" r="j" v="79"
l="Q" r="x" v="31"
l="Q" r=";" v="60"
l="Q" r="]" v="32"
l="R" r="C" v="-18"
l="R" r="G" v="-19"
l="R" r="O" v="-20"
l="R" r="Q" v="-20"
l="R" r="S" v="-27"
l="R" r="T" v="-20"
l="R" r="V" v="-28"
l="R" r="W" v="-18"
l="R" r="Y" v="-30"
l="R" r="e" v="-36"
l="R" r="o" v="-42"
l="R" r="v" v="-26"
l="R" r="w" v="-33"
l="R" r="y" v="-33"
l="S" r="A" v="-15"
l="S" r="J" v="-9"
l="S" r="T" v="-14"
l="S" r="V" v="-14"
l="S" r="W" v="-15"
l="S" r="X" v="-13"
l="S" r="Y" v="-20"
l="S" r="v" v="-23"
l="S" r="w" v="-17"
l="S" r="y" v="-25"
l="T" r="A" v="-160"
l="T" r="C" v="-42"
l="T" r="G" v="-59"
l="T" r="J" v="-65"
l="T" r="O" v="-58"
l="T" r="Q" v="-58"
l="T" r="S" v="-10"
l="T" r="T" v="28"
l="T" r="a" v="-160"
l="T" r="c" v="-177"
l="T" r="d" v="-147"
l="T" r="e" v="-182"
l="T" r="g" v="-151"
l="T" r="m" v="-127"
l="T" r="n" v="-127"
l="T" r="o" v="-182"
l="T" r="p" v="-127"
l="T" r="q" v="-147"
l="T" r="r" v="-127"
l="T" r="s" v="-153"
l="T" r="u" v="-127"
l="T" r="v" v="-92"
l="T" r="w" v="-86"
l="T" r="x" v="-90"
l="T" r="y" v="-93"
l="T" r="z" v="-142"
l="T" r=";" v="-114"
l="T" r=":" v="-134"
l="U" r="A" v="-45"
l="U" r="J" v="-40"
l="V" r="A" v="-96"
l="V" r="C" v="-18"
l="V" r="G" v="-25"
l="V" r="J" v="-80"
l="V" r="O" v="-27"
l="V" r="Q" v="-27"
l="V" r="S" v="-12"
l="V" r="V" v="9"
l="V" r="a" v="-114"
l="V" r="c" v="-103"
l="V" r="d" v="-87"
l="V" r="e" v="-102"
l="V" r="g" v="-100"
l="V" r="m" v="-50"
l="V" r="n" v="-50"
l="V" r="o" v="-86"
l="V" r="p" v="-50"
l="V" r="q" v="-87"
l="V" r="r" v="-50"
l="V" r="s" v="-90"
l="V" r="u" v="-50"
l="V" r="y" v="-35"
l="V" r="z" v="-82"
l="V" r=";" v="-108"
l="V" r=":" v="-73"
l="W" r="A" v="-93"
l="W" r="C" v="-22"
l="W" r="G" v="-22"
l="W" r="J" v="-88"
l="W" r="O" v="-22"
l="W" r="Q" v="-22"
l="W" r="S" v="-10"
l="W" r="X" v="-13"
l="W" r="a" v="-71"
l="W" r="c" v="-78"
l="W" r="d" v="-72"
l="W" r="e" v="-75"
l="W" r="g" v="-54"
l="W" r="m" v="-60"
l="W" r="n" v="-60"
l="W" r="o" v="-86"
l="W" r="p" v="-60"
l="W" r="q" v="-72"
l="W" r="r" v="-60"
l="W" r="s" v="-73"
l="W" r="u" v="-60"
l="W" r="v" v="-34"
l="W" r="y" v="-53"
l="W" r=";" v="-156"
l="X" r="C" v="-57"
l="X" r="G" v="-65"
l="X" r="O" v="-57"
l="X" r="Q" v="-57"
l="X" r="S" v="-20"
l="X" r="d" v="-44"
l="X" r="e" v="-39"
l="X" r="g" v="-9"
l="X" r="o" v="-38"
l="X" r="q" v="-44"
l="X" r="t" v="-31"
l="X" r="u" v="-38"
l="X" r="v" v="-55"
l="X" r="w" v="-49"
l="X" r="y" v="-43"
l="Y" r="A" v="-152"
l="Y" r="C" v="-67"
l="Y" r="G" v="-67"
l="Y" r="J" v="-112"
l="Y" r="O" v="-66"
l="Y" r="Q" v="-66"
l="Y" r="S" v="-17"
l="Y" r="Z" v="-10"
l="Y" r="a" v="-134"
l="Y" r="c" v="-159"
l="Y" r="d" v="-131"
l="Y" r="e" v="-147"
l="Y" r="f" v="-62"
l="Y" r="g" v="-142"
l="Y" r="i" v="-32"
l="Y" r="j" v="-49"
l="Y" r="m" v="-94"
l="Y" r="n" v="-94"
l="Y" r="o" v="-153"
l="Y" r="p" v="-94"
l="Y" r="q" v="-131"
l="Y" r="r" v="-94"
l="Y" r="s" v="-115"
l="Y" r="t" v="-44"
l="Y" r="u" v="-94"
l="Y" r="v" v="-69"
l="Y" r="w" v="-62"
l="Y" r="x" v="-70"
l="Y" r="y" v="-65"
l="Y" r="z" v="-100"
l="Y" r=";" v="-138"
l="Y" r=":" v="-154"
l="Z" r="A" v="-11"
l="Z" r="C" v="-25"
l="Z" r="G" v="-24"
l="Z" r="O" v="-24"
l="Z" r="Q" v="-24"
l="Z" r="W" v="-7"
l="Z" r="Y" v="-7"
l="Z" r="a" v="-10"
l="Z" r="c" v="-12"
l="Z" r="d" v="-18"
l="Z" r="e" v="-31"
l="Z" r="o" v="-29"
l="Z" r="q" v="-18"
l="Z" r="v" v="-45"
l="Z" r="w" v="-38"
l="Z" r="y" v="-37"
l="a" r="f" v="-12"
l="a" r="t" v="-19"
l="a" r="v" v="-34"
l="a" r="w" v="-14"
l="a" r="x" v="-19"
l="a" r="y" v="-38"
l="b" r="f" v="-17"
l="b" r="s" v="-10"
l="b" r="t" v="-9"
l="b" r="v" v="-10"
l="b" r="w" v="-10"
l="b" r="x" v="-41"
l="b" r="y" v="-10"
l="b" r="z" v="-28"
l="c" r="a" v="-17"
l="c" r="o" v="-17"
l="e" r="f" v="-18"
l="e" r="t" v="-11"
l="e" r="v" v="-10"
l="e" r="w" v="-10"
l="e" r="x" v="-31"
l="e" r="y" v="-13"
l="e" r="z" v="-20"
l="f" r="a" v="-40"
l="f" r="c" v="-45"
l="f" r="d" v="-53"
l="f" r="e" v="-51"
l="f" r="f" v="-20"
l="f" r="g" v="-60"
l="f" r="o" v="-43"
l="f" r="q" v="-53"
l="f" r="s" v="-27"
l="f" r="v" v="13"
l="f" r="w" v="6"
l="f" r="y" v="10"
l="f" r="z" v="-20"
l="g" r="a" v="-38"
l="g" r="c" v="-12"
l="g" r="d" v="-19"
l="g" r="e" v="-17"
l="g" r="g" v="19"
l="g" r="o" v="-14"
l="g" r="q" v="-19"
l="g" r="t" v="-31"
l="h" r="f" v="-12"
l="h" r="t" v="-19"
l="h" r="v" v="-34"
l="h" r="w" v="-14"
l="h" r="x" v="-19"
l="h" r="y" v="-38"
l="k" r="a" v="-35"
l="k" r="c" v="-48"
l="k" r="d" v="-56"
l="k" r="e" v="-66"
l="k" r="o" v="-69"
l="k" r="q" v="-56"
l="k" r="s" v="-19"
l="k" r="t" v="-10"
l="k" r="u" v="-26"
l="m" r="f" v="-12"
l="m" r="t" v="-19"
l="m" r="v" v="-34"
l="m" r="w" v="-14"
l="m" r="x" v="-19"
l="m" r="y" v="-38"
l="n" r="f" v="-12"
l="n" r="t" v="-19"
l="n" r="v" v="-34"
l="n" r="w" v="-14"
l="n" r="x" v="-19"
l="n" r="y" v="-38"
l="o" r="v" v="-9"
l="o" r="w" v="-8"
l="o" r="x" v="-40"
l="o" r="y" v="-11"
l="o" r="z" v="-27"
l="p" r="f" v="-17"
l="p" r="s" v="-10"
l="p" r="t" v="-9"
l="p" r="v" v="-10"
l="p" r="w" v="-10"
l="p" r="x" v="-41"
l="p" r="y" v="-10"
l="p" r="z" v="-28"
l="q" r="g" v="10"
l="r" r="a" v="-42"
l="r" r="c" v="-30"
l="r" r="d" v="-28"
l="r" r="e" v="-27"
l="r" r="g" v="-28"
l="r" r="o" v="-33"
l="r" r="q" v="-28"
l="r" r="s" v="-35"
l="r" r="v" v="19"
l="r" r="w" v="11"
l="r" r="y" v="10"
l="s" r="f" v="-19"
l="s" r="t" v="-23"
l="s" r="v" v="-31"
l="s" r="w" v="-10"
l="s" r="x" v="-22"
l="s" r="y" v="-37"
l="s" r="z" v="-18"
l="t" r="a" v="-25"
l="t" r="c" v="-25"
l="t" r="d" v="-23"
l="t" r="e" v="-22"
l="t" r="o" v="-20"
l="t" r="q" v="-23"
l="t" r="t" v="-29"
l="v" r="a" v="-30"
l="v" r="c" v="-25"
l="v" r="d" v="-20"
l="v" r="e" v="-20"
l="v" r="f" v="11"
l="v" r="g" v="-28"
l="v" r="o" v="-19"
l="v" r="q" v="-20"
l="v" r="s" v="-9"
l="v" r="t" v="10"
l="v" r="v" v="12"
l="v" r="w" v="12"
l="v" r="y" v="12"
l="v" r="z" v="-26"
l="w" r="a" v="-23"
l="w" r="c" v="-20"
l="w" r="d" v="-18"
l="w" r="e" v="-18"
l="w" r="f" v="6"
l="w" r="g" v="-18"
l="w" r="o" v="-19"
l="w" r="q" v="-18"
l="w" r="s" v="-18"
l="w" r="t" v="4"
l="w" r="v" v="12"
l="w" r="w" v="8"
l="w" r="y" v="12"
l="w" r="z" v="-17"
l="x" r="a" v="-37"
l="x" r="c" v="-46"
l="x" r="d" v="-44"
l="x" r="e" v="-54"
l="x" r="o" v="-55"
l="x" r="q" v="-44"
l="x" r="s" v="-12"
l="x" r="t" v="6"
l="x" r="u" v="-20"
l="y" r="a" v="-31"
l="y" r="c" v="-26"
l="y" r="d" v="-24"
l="y" r="e" v="-25"
l="y" r="f" v="10"
l="y" r="g" v="-26"
l="y" r="o" v="-24"
l="y" r="q" v="-24"
l="y" r="s" v="-19"
l="y" r="t" v="10"
l="y" r="v" v="12"
l="y" r="w" v="8"
l="y" r="y" v="10"
l="y" r="z" v="-17"
l="z" r="a" v="-34"
l="z" r="c" v="-45"
l="z" r="d" v="-46"
l="z" r="e" v="-46"
l="z" r="f" v="-10"
l="z" r="g" v="-17"
l="z" r="o" v="-45"
l="z" r="q" v="-46"
l="z" r="s" v="-22"
l="z" r="u" v="-10"
l="z" r="v" v="-18"
l="z" r="w" v="-22"
l="z" r="y" v="-18"


This is , so the shortest answer (in bytes) wins.


I know this challenge is going to need a lot of work before it's ready for main. Please hold criticisms for now. Helpful ideas and thoughts are welcome.

  • \$\begingroup\$ I'm not sure that the problem is well defined. There's a reason it's called font hinting: the rendering application is free to take it into account or not, or even to apply more complex logic. E.g. some fonts have multiple sets of font hints for different contexts. There are other complex issues. A font can have Latin and Cyrillic letters and define hints for kerning between pairs of Latin and pairs of Cyrillic but not between Latin and Cyrillic; however, some letters may have identical glyphs, so a judgement on whether the kerning is "correct" might be ambiguous. Then there's antialiasing. \$\endgroup\$ May 24, 2017 at 6:15
  • \$\begingroup\$ @PeterTaylor Good notes. I will likely restrict the character set. I just wanted to start getting ideas down in the sandbox. \$\endgroup\$
    – Poke
    May 24, 2017 at 6:51
  • \$\begingroup\$ Very ambiguous. \$\endgroup\$
    – anna328p
    May 25, 2017 at 17:48
  • \$\begingroup\$ @Mendeleev It's not done yet. I'm aware it's ambiguous. \$\endgroup\$
    – Poke
    May 26, 2017 at 16:10
  • \$\begingroup\$ Looking at developer.apple.com/fonts/TrueType-Reference-Manual/RM06/… I can see a number of issues to address. 16- vs 32-bit entries? Should multiple tables be combined or printed separately? All tables or only tables with certain coverage values? Which of the four defined formats need to be supported? Do you have a test case which covers glyph index differing from codepoint? \$\endgroup\$ Sep 16, 2017 at 17:28
  • \$\begingroup\$ @PeterTaylor I have a proof of concept that I wrote (it's the reason I have taken so long to update this) and I'm planning to address all of your questions. Thanks for doing a bit of research to help me out, though :] \$\endgroup\$
    – Poke
    Sep 16, 2017 at 18:57
  • \$\begingroup\$ Downvoter, why? \$\endgroup\$
    – Poke
    Oct 4, 2017 at 21:03

Six Flags over HTTP

Let's say you need to transmit six boolean flags in a URL string. Obviously you could do it with six ones or zeroes, but you want better compression. With a little math you can pack them into two characters using 0-7 octal.

How about mapping all six to a single ASCII character? Here we have a problem: you are not allowed to use , / ? : @ & = + $ # or space. Now the range of printable ASCII no longer has 64 valid characters in a row.

In Javascript (or another language that can run from a web page, if any), what is the shortest code for a pair of functions to encode and decode this data, between an array of six booleans and a single character?

  • \$\begingroup\$ -1 language restriction, most languages have HTTP libraries so I think any language should be allowed \$\endgroup\$
    – ASCII-only
    Sep 24, 2017 at 13:11
  • \$\begingroup\$ This challenge could be improved by rephrasing it to: "Write a bijective function between an array of six booleans and a single printable character excluding the characters ,/?:@&=+$# ". Mentioning that the encoder and decoder should be separate programs/functions would be helpful. Also, may the encoder and decoder share code? \$\endgroup\$ Sep 24, 2017 at 22:08

Count letter frequency

Inspired by question Tweetable hash function challenge, you should take the English dictionary used there and produce a program or function that outputs the the absolute and relative frequency of each character. It is CASE SENSITIVE and the APOSTROPHE is also accountable as a real letter.

Example of a valid output format (but with stupid guessing values):

A      5566    20%
Z        60     0.2%
a     27000    30%
z       120     0.01%
'       450     3.5%

It is , but no answer will be accepted. Wanna know shortest script for each language.

  • 1
    \$\begingroup\$ -1 (01) Don't rely on another challenge to define yours; include all the information we need in your write-up. (02) Make an effort to come up with some actual test cases - do you honestly expect us to verify our solutions against "stupid guessing values"? \$\endgroup\$
    – Shaggy
    Sep 30, 2017 at 0:55

Is it a perfect loop?

Your task is to take a GIF or an animated image in any reasonable format as input (including taking the file name of a GIF in the current directory), and output whether it is a "perfect loop" - that is, the frames transition seamlessly from the end to the start, and a human cannot notice where it starts and ends at first glance. Return or print a truthy value if it is a perfect loop, otherwise print or return a falsy value.


Winners will be determined from the percentage of test cases they get correct. In the event of a tie, highest votes wins. You can view test cases at https://ghostbin.com/paste/m3yaw. Show your score against the test cases when you post.


If you are not taking input in a GIF, please provide a program that will convert a GIF to your desired format.

Images corresponding to a truthy value have been taken from /r/perfectloops and for falsy test cases, /r/almostperfectloops and /r/gifs.


  • Hard coding is not allowed (violates standard loophole 1 and 2).
  • You must provide consistent results for the same GIF (no randomness)
  • Remember, this is not , so byte count is not needed in your solution. Just post the language name and add the percentage correct when I comment.
  • \$\begingroup\$ I'm not sure it's as simple as comparing the first to the last frame, if it is we'd have duplicate frames. is this challenge allowing HTTP requests? \$\endgroup\$
    – tuskiomi
    Oct 17, 2017 at 21:15
  • \$\begingroup\$ If hashing the inputs is not allowed, then you should clearly define what constitutes a “perfect loop”. It's not good to extrapolate from a handful of test cases where the pass/fail cases are very similar. \$\endgroup\$
    – japh
    Oct 18, 2017 at 14:31

Highest code size∕output ratio to generate a large executable section inside an elf file.

Your challenge is to create the shortest code in your language of choice or the tools of your choice (like objcopy) that will create an elf file with a the executable section as large as possible.
I mean that if I extract the.text section of the elf binary, the resulting extracted file should be at least 90% of the elf binary.


  • The program should takes the desired section size as input.
  • The .text section name needs to corresponds to the executable section.
  • The type of the .text section should bePROGBITSand it should contains instructions.
  • The elf file should have a .shstrtab section.
  • The .text section should be readable and writable.
  • The target architecture should be Pnacl or armelv7 or x86_64.
  • The elf file should be valid and pass Google nacl’s validation whitelist in order to be loaded (but I don´t care if the sandbox segfault).
    If you have no idea about what Google native client is, just create a script that call the patched version of binutils from the nacl_sdk, or make sure the elf file is valid and can be executed on Linux.

Of course, you normally can’t use a compiler because it would takes too much computational years in order to finish.


The answer with the highest code size∕program output ratio.

  • 1
    \$\begingroup\$ Why not make scoring output size / code size? \$\endgroup\$
    – anna328p
    Apr 4, 2017 at 3:49
  • \$\begingroup\$ Make it a code-challenge \$\endgroup\$
    – anna328p
    Apr 4, 2017 at 3:49
  • \$\begingroup\$ This is essentially the same challenge as this one, and would be closed as a duplicate. Although it's not exactly the same, some answers to the previous question would require very little modification and answers to this question would also require very little modification to be answers to the other one. \$\endgroup\$ Apr 4, 2017 at 8:37
  • \$\begingroup\$ @Alt-F4 : it was a code challenge. \$\endgroup\$ Apr 4, 2017 at 21:52
  • \$\begingroup\$ @PeterTaylor : they were no answer to the previous question. In order to be closed as a duplicate the target needs to be already answered. You known it was closed an unclear, so please suggest change to make this answer clearer. \$\endgroup\$ Apr 4, 2017 at 21:54
  • \$\begingroup\$ Huh? It's open and has 15 answers. \$\endgroup\$ Apr 4, 2017 at 22:09
  • \$\begingroup\$ @PeterTaylor sorry, I thought to an another question that was closed as unclear and didn’t take time to read your link. In that case NO, the aim is to not use the compiler in order to actually build the file. This normally can’t be done with a compiler or an assembler. \$\endgroup\$ Apr 4, 2017 at 22:16
  • \$\begingroup\$ Can't it? Why not? \$\endgroup\$
    – wizzwizz4
    Dec 16, 2017 at 19:55
  • \$\begingroup\$ Wait... shortest code that generate any program? Or what? Don't think this is a good idea... \$\endgroup\$
    Jan 6, 2018 at 12:10
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