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

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4629 Answers 4629

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\$\begingroup\$

Forward foo, reverse bar, but avoid dead code

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6
  • \$\begingroup\$ Trying to count "dead bytes" is a bad idea. Consider this Pyth program. The string "rab" is interpreted and the interpreted code is even executed but since the output is suppressed it does nothing observable. This makes it extremely difficult to determine what dead code is (only made worse by not counting unexecuted code), which will almost certainly result in this being closed. \$\endgroup\$ Oct 3, 2023 at 19:16
  • \$\begingroup\$ @FryAmTheEggman This is obviously no dead code. This may make things boring for some languages, but the idea is to bring up creative solutions in other languages. \$\endgroup\$
    – Philippos
    Oct 4, 2023 at 7:55
  • \$\begingroup\$ @FryAmTheEggman I found a better definition of »dead code«, that takes in account your example. \$\endgroup\$
    – Philippos
    Dec 1, 2023 at 6:52
  • \$\begingroup\$ That is better, but what does "most other characters" mean? I think you would want to say "any other byte", but that will make languages that refuse to interpret certain bytes unable to have any dead code (which doesn't seem like what you want). \$\endgroup\$ Dec 1, 2023 at 15:49
  • \$\begingroup\$ You got me right. Even in the python or shell examples, no one shall argue, that replacing the comment characters by a newline will change the behaviour. But there is no doubt that you can replace those by most characters without anything happens. I don't want to give an exact definition of »most«. This is not legislation, it's about giving the direction of thinking, where the spirit of the challenge (and hopefully the fun) can be found. \$\endgroup\$
    – Philippos
    Dec 1, 2023 at 16:49
  • \$\begingroup\$ I think this is code-challenge. \$\endgroup\$
    – Jakav
    Dec 15, 2023 at 1:59
1
\$\begingroup\$

Implement a typeface based on a 3x3 bitmap matrix

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1
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Is it mate in one?

Given a 8x8 chessboard, determine if white can checkmate black in one move. For this challenge, you may assume there are only 4 types of pieces:

kings (represented by a "k")

queens (represented by a "q")

rooks (represented by a "r")

and knights (represented by a "n".)

The black version of these pieces are the capital version of the white pieces. You may assume both sides start with a king, and that every position will be legal, (e. g. there won't be any positions where white can just take black's king) and white will never be in check. Squares with no pieces on them can be any char you like that is not in "kqrnKQRN". You will not have to consider short or long castles. All pieces move the same way they do in normal chess.

An example

For example, in the following position:

......RK
.......Q
........
......nq
.........
.........
.........
k.......

White can play the move Qxh7, checkmate.


  • I have not tried this myself.
  • Any suggestions or/for test cases?
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2
1
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Validate a CPF number

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1
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Aircraft registration numbers

Write a program that takes a United States aircraft registration number and returns a 24-bit ICAO hex code corresponding to that registration and vice-versa.

An aircraft registration number always begins with an N and is followed by 1 to 5 characters: 1 to 5 digits and then 0 to 2 letters. That is, one of the following three patterns:

  • N plus 1 to 5 digits
  • N plus 1 to 4 digits then one letter
  • N plus 1 to 3 digits then two letters

The first digit cannot be 0 and the letters I and O are not used. The letters always follow the digits.

ICAO hex codes assigned to the US are numbers from A00001 to ADF7C7 (in hexadecimal). They are assigned in alphanumeric order: A00001 corresponds to N1, A00002 corresponds to N1A, A00003 to N1AA, A00004 to N1AB, etc., up to ADF7C7 for N99999.

Some test cases:

Registration ICAO code (hex) ICAO code (decimal)
N17CA A11707 10557191
N1PP A00155 10486101
N959ZP AD5863 11360355
N999ZZ ADF669 11400809

You can assume no invalid inputs will be given.

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1
  • \$\begingroup\$ s/numbers/digits/ \$\endgroup\$
    – Philippos
    Jan 15 at 15:43
1
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Validate a codice fiscale

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1
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The TAK function

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1
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This is my first challenge here, and I know I'm not supposed to start with a KotH. But I had this idea and I think it is simple enough while allowing more advanced strategies, so here it is:


Tank Game

There are two tanks on a 16×16 toroidal grid (wrapping in both directions), one starting at (0, 0) and its opponent starting at (8, 8). The objective is to occupy the enemy base (starting point) without getting shot. Some grid cells are walls, which tanks can't move, shoot or see through. Each submission includes 2 separate programs that form a team, a commander and a tank driver. Direct communication between them is not allowed, but actions of the commanders are visible to the drivers, allowing you to encode some information that way.

The commander

  • Sees the entire map and the positions of the tanks.
  • Can build or destroy walls.

The tank

  • Has very limited vision but knows its position.
  • Sees the actions of both the friendly and the enemy commander.
  • Can move in a straight line up to 3 cells.
  • Can shoot in a straight line.

Details of the game

The tanks and commanders take turns in the following order:

  1. Commander of 1st submission
  2. Tank driver of 2nd submission
  3. Commander of 2nd submission
  4. Tank driver of 1st submission

Although from an outside perspective your tank may start at either (0, 0) or (8, 8), the map and all other coordinates provided to your programs (including enemy actions) will be translated by the controller to make it look like your tank started at (0, 0) and has to go to (8, 8). This is done so your program doesn't have to check where it started from.

The starting position looks like this:

      | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15 <--- Coordinates observed by Tank 1
      | 8| 9|10|11|12|13|14|15| 0| 1| 2| 3| 4| 5| 6| 7 <--- Coordinates observed by Tank 2
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 0  8 |T1|  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 1  9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 2 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 3 11 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 4 12 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 5 13 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 6 14 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 7 15 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 8  0 |  |  |  |  |  |  |  |  |T2|  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
 9  1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
10  2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
11  3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
12  4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
13  5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
14  6 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
15  7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
^^ ^^
|| ++---- Coordinates observed by Tank 2
++---- Coordinates observed by Tank 1

T1: Starting position of Tank 1, target of Tank 2
T2: Starting position of Tank 2, target of Tank 1

The commander receives two arguments, map and enemyAction:

  • map: (x: number, y: number) => Cell:

    • A Cell is one of the following:

      • ' ' (space): empty cell
      • '#': wall
      • 'F': friendly tank
      • 'E': enemy tank
    • x and y wrap around (mod 16).

    • You can't directly modify the map

  • enemyAction: Action

    • type Action = { action: 'B'|'D', x: number, y: number } | null
      
    • The last action of the enemy commander.
    • Given only for convenience, it could be computed from the map.

And must return one of the following actions:

  • { action: 'B', x: number, y: number }:

    • Builds a wall.
    • Walls can not be built on the two bases ((0,0) and (8,8)) and on cells with tanks. Attempting to do so is an error.
  • { action: 'D', x: number, y: number }:

    • Destroys a wall.
    • Attempting to destroy a non-existing wall is an error.
  • null:

    • Does nothing.

The tank driver receives four arguments:

  • x: number, y: number: position of your tank
  • friendlyAction: Action, enemyAction: Action: the last actions of the friendly and enemy commanders.

And must return one of the following actions:

  • { action: 'M', direction: Direction, distance: number }

    • Move the tank (up to 3 cells in a straight line, instantly).
    • Direction is one of the following:
      • 'U': negative y direction (up)
      • 'L': negative x direction (left)
      • 'D': positive y direction (down)
      • 'R': positive x direction (right)
    • 1 <= distance <= 3
    • If the tank can't move distance cells because a wall or the enemy tank is in the way, it stops moving before colliding with that (it will not move at all if the obstacle is directly in front of it).
  • { action: 'S', direction: Direction }

    • Shoot.
    • The bullet travels in a straight line until it hits a wall or a tank, instantly.
    • If you hit the enemy tank, you immediately win the round 2-0.
    • You can't shoot yourself.
  • { action: 'L', callback: (Result) => void }

    • Look around (in straight lines in all 4 directions).
    • type Result = { U: number, L: number, D: number, R: number, enemyDirection: Direction | null }
      
      • U, L, D and R are the lengths of empty cells in the respective directions.
      • enemyDirection is the relative direction of the enemy tank, if visible. If there are no walls in the row/column, it will be the direction which the enemy is closer in.

Scoring

  • Reaching (8,8) and surviving until your next turn: win 3-0
  • Shooting down the enemy tank: win 2-0
  • Reaching turn number 40 without a winner: draw 1-1
  • Throwing an error or returning invalid action: lose 0-3

Technical details

The submissions must consist of two separate programs written in . The programs may not use any APIs that aren't part of the language itself (i.e. browser or Node.js APIs) and may not introduce globally observable changes (including but not limited to prototype pollution and mutating built-in objects). The programs may not run code asynchronously.

To keep the game reproducable, Math.random() will be replaced with a seeded PRNG, which you can use for randomness, but please don't introduce any other non-determinism.

The commander must be a script with a function commander in the top-level scope. Likewise, the tank driver has to have a function named tankDriver. You may create helper functions and variables for storing state (state will be reset after each game).

Each submission will be run against every other submission in pairs, 2×5 times for each pair (each submission starting 5 times). The maps will be randomly generated. The submission reaching the highest total score wins the challenge.

The controller is not yet done, I want to get feedback about the challenge first.

Besides the ones listed above, standard loopholes also apply.

I reserve my right to disqualify entries that violate the above rules or ones that I deem to be cheating. I will always notify the author in advance and allow them to fix the problems.

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  • \$\begingroup\$ If all tanks start at (0, 0), does that mean multiple tanks can be on the same tile? And also, what do the numbers in C1 T2 C2 T1 mean? \$\endgroup\$ Jan 25 at 14:25
  • \$\begingroup\$ @AlanBreadel From an outside perspective, one tank starts at (0,0) and the other at (8,8) as mentioned in the introduction. But both tanks see the world as if the tile they started on is (0,0), so they don't have to use conditional logic to decide if they should go to (0,0) or (8,8). I'll try to clarify this. Also, I can easily remove this rule if it's too confusing. C1 T2 C2 T1 means "commander of first player; tank of second player; controller of second player; driver of first player" \$\endgroup\$
    – FZs
    Jan 25 at 15:15
  • \$\begingroup\$ Ah, so each tank is paired up with one other tank. Is that other tank with another submission or something else? \$\endgroup\$ Jan 25 at 15:20
  • \$\begingroup\$ Yeah, 2 tanks at a time. One submission consists of one team of a commander and a driver, controlling one tank and editing the map. \$\endgroup\$
    – FZs
    Jan 25 at 15:22
  • \$\begingroup\$ I'm pretty sure king of the hills are supposed to put all submissions against each other, but this is probably also fine. Maybe a swiss format? (e. g. one tank and commander against every other tank and commander team.) \$\endgroup\$ Jan 25 at 15:24
  • \$\begingroup\$ Also, (0, 0) and (8, 8) imply a 9x9 grid (assuming those are the edges. I'm a bit confused because it specifies 16x16.) It should be (0, 0) and (7, 7) with 0-based indexing, or (1, 1) and (8, 8) with 1-based indexing. \$\endgroup\$ Jan 25 at 15:25
  • \$\begingroup\$ This is described near the end, "Each submission will be run against every other submission [...]". Also, I have seen KotH's on this format on CGCC \$\endgroup\$
    – FZs
    Jan 25 at 15:27
  • \$\begingroup\$ The map is 16×16, and toroidal (meaning wrapping around). This means (0,0) and (8,8) are the furthest cells (because to get to (15,15) you could just wrap around from 0 to 15 in two steps). \$\endgroup\$
    – FZs
    Jan 25 at 15:30
  • \$\begingroup\$ If a tank moves right say, 5 squares, is that instant or does it take 5 turns with 1 square per turn? \$\endgroup\$ Jan 25 at 15:39
  • \$\begingroup\$ I'll have to clarify that. Tanks can move up to 3 cells instantly. They can move longer than 3 cells in multiple turns \$\endgroup\$
    – FZs
    Jan 25 at 15:44
  • \$\begingroup\$ So for example I try to move 7 tiles, I'll move 3 in one turn, 3 in the next, and 1 in the turn after that, right? But then I decide I want to do something else on the second or third turn. Can I stop the movement and do something else or does it override everything? \$\endgroup\$ Jan 25 at 17:05
  • \$\begingroup\$ I already edited my post, see the edit. You can't return "move 7 tiles", that is an error. You'd have to go "move 3", "move 3", "move 1" to move 7 in effect. \$\endgroup\$
    – FZs
    Jan 25 at 19:18
1
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Fastest bytewise comparisons in 64-bit unsigned integers

[tag:i-don't-know]

  • Create a function that accepts two 64-bit unsigned integers, a and b.

  • Compare each corresponding byte in a and b.

  • If the byte in a is greater than the byte in b in the same position, set the corresponding byte in the output to 255.

  • Otherwise, set the corresponding byte in the output to 0.

  • Return the resulting 64-bit unsigned integer.

Restrictions: the code runs in x86-64, no explict SSEx, AVXx (is ok if the compiler vectorices the result)

Example:

a =      202      141        1      123       61       53       40 251
b =      158       75      185      217        5       90      152 225
a = 11001010 10001101 00000001 01111011 00111101 00110101 00101000 11111011
b = 10011110 01001011 10111001 11011001 00000101 01011010 10011000 11100001
a>b=     255      255        0        0      255        0        0      255
a>b=11111111 11111111 00000000 00000000 11111111 00000000 00000000 11111111
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  • \$\begingroup\$ GCC compiles it to a single instruction so it seems bad \$\endgroup\$
    – l4m2
    Jan 29 at 6:48
  • \$\begingroup\$ @l4m2 I see, is SSE. What about non using bytes, like using numbers with 4 bits, 5 bits, 9 bits \$\endgroup\$
    – vakvakvak
    Jan 29 at 18:11
  • \$\begingroup\$ @l4m2 The compiler using SSE means that 64 bit registers (non SIMD) remain unused, so there is an opportunity to extract more performance, although I don't know how to take advantage of it. By the way, without compiler optimizations, your code does unnecessary branches. If you store 0,1 in each byte, C[i] = A[i] > B[i], and at the end return the C*255, you avoid a lot of ?. \$\endgroup\$
    – vakvakvak
    Jan 30 at 8:50
1
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Demonstrate that 1³+2³+...+n³ = (1+2+...+n)²

The following image is a proof without words that \$\sum_{i=1}^{n}i^3=\left(\sum_{i=1}^{n}i\right)^2\$, or in other words, the sum of the first n cubes equals the square of the sum of the first n positive integers.

enter image description here

The image contains (the equivalent of) 1 square with side length 1, 2 squares with side length 2, etc up to 5 squares with side length 5. The 1x1 squares have a total area of 1x1x1 = 1³, the 2x2 squares have a total area of 2x2x2=2³, and the 5x5 squares have a total area of 5x5x5=5³. Overall, the total area of all the squares is 1³ + 2³ + 3³ + 4³ + 5³.

But, the larger square has a side length of 1+2+3+4+5, and an area of (1+2+3+4+5)². And, since all the small squares take up the same space as the large square, they must have the same total area, so 1³+2³+3³+4³+5³ = (1+2+3+4+5)². This can be shown to work for all positive integers.

The above can also be represented as the following integer matrix:

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

This matrix can be thought of as a series of "bands", where each band #n contains all points at coordinates (x, y) where max(x, y) = n. Every point in the first band, containing the point at coordinates [1, 1], contains 1; the second, containing [[1, 2], [2, 2], [2, 1]], and the third, containing [[1,3],[2,3],[3,3],[3,2],[3,1]], contain only 2s, the next 3 bands contain only 3s, and so on up to 5.

Your challenge is to, given a positive integer n, output the corresponding integer matrix for n. The above matrix should be output when 5 is input.

This is , shortest wins!

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3
  • \$\begingroup\$ Can I print this matrix infinitely? Or take i,j and output the element in those coordinates? \$\endgroup\$ Jan 29 at 3:55
  • \$\begingroup\$ @CommandMaster I'm gonna say no to that, I don't really see the point of the first and the second oversimplifies things. \$\endgroup\$
    – emanresu A
    Jan 29 at 6:34
  • \$\begingroup\$ Looks similar to the one that output \$\begin{matrix}1&2&3&4\\2&2&3&4\\3&3&3&4\\4&4&4&4\end{matrix}\$ \$\endgroup\$
    – l4m2
    Jan 29 at 6:41
1
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Possible moves in Othello/Reversi

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1
  • \$\begingroup\$ This actually seems interesting, commenting since it's late and otherwise you wouldn't see \$\endgroup\$
    – mousetail
    Jan 25 at 14:30
1
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Remove falsy rows and columns

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1
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Is it a coordinate-sum list?

In this challenge, we define a coordinate-sum list as a ragged list of positive integers where each value is the sum of its 0-indexed-coordinates in the array. For example, the following ragged list is a coordinate-sum list:

[[[0, 1],
  [1, 2, 3],
  [2]],
 [[1],
  [2, 3, 4],
  3]],
 2]]

In this array, the 4 is the third item of the second item of the second item of the list, or arr[1][1][2] (0-indexing), which gives it the coordinate [1, 1, 2], which sums to 4. Likewise, the 0 is arr[0][0][0] and has the coordinate [0, 0, 0] which sums to 0, and this is true for all items in the list.

This, however, is not a coordinate-sum list:

[[0, 1, 2],
 [1, 2, 3, 4],
 [2, 3, 6, 5],
 3]

Although all the other entries are the sums of their coordinates, the 6 at the third item of the third row has coordinate [2, 2], which sums to 4, but its value is 6, so this is not a coordinate-sum list.

Your challenge is to, given a nonempty ragged list of positive integers containing no empty lists at any level, determine whether it is a coordinate-sum list. You may instead validate the input via 1-indexing (i.e. [[2, 3], [3, 4, 5], 2] would be valid).

This is , shortest wins!

Testcases

All of these use 0-indexing. If your answer uses 1-indexing, add to each value its depth in the list.

Truthy

[0]
[0, 1, 2, 3]
[[0, 1, 2], [1, 2, 3, 4], 2]
[[[0, 1, 2, 3], [1, 2]], [[1, 2, 3], [2, 3, 4, 5, 6], [3, 4, 5]]]
[[0, 1, 2, 3, 4, 5, 6, 7], 1, [2, 3, 4, [5, 6, 7], 6], [3, 4, 5, 6]]
[[[[0, 1], [1, 2], 2], [[1, 2, 3], [2, 3]]], [[[1, 2], [2, 3, 4]], [[2, 3], [3, 4, 5, 6, 7]]], [2, 3]]
[[[[[0, 1, 2], [1, 2, 3], [2, 3, 4], [3, 4, 5]], [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]], [[2, 3, 4], [3, 4, 5], [4, 5, 6], [5, 6, 7]]], [[[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]], [[2, 3, 4], [3, 4, 5], [4, 5, 6], [5, 6, 7]], [[3, 4, 5], [4, 5, 6], [5, 6, 7], [6, 7, 8]]], [[[2, 3, 4], [3, 4, 5], [4, 5, 6], [5, 6, 7]], [[3, 4, 5], [4, 5, 6], [5, 6, 7], [6, 7, 8]], [[4, 5, 6], [5, 6, 7], [6, 7, 8], [7, 8, 9]]], [[[3, 4, 5], [4, 5, 6], [5, 6, 7], [6, 7, 8]], [[4, 5, 6], [5, 6, 7], [6, 7, 8], [7, 8, 9]], [[5, 6, 7], [6, 7, 8], [7, 8, 9], [8, 9, 10]]], [[[4, 5, 6], [5, 6, 7], [6, 7, 8], [7, 8, 9]], [[5, 6, 7], [6, 7, 8], [7, 8, 9], [8, 9, 10]], [[6, 7, 8], [7, 8, 9], [8, 9, 10], [9, 10, 11]]]]]

Falsy

[2]
[[1, 2], [2, 3, 4]]
[[0, 1], [2, 3]]
[[[1, 2, 3], 4, [3, 4, 5]], [[2, 3, 4], [3, 4, 5], [4, 5, 6]], [[3, 4, 5], [4, 5, 6], [5, 6, 7, 8], [6, [7, 8], 8]]]
[4, 3, 2, 1, 0]
[[4, 3, 2], [3, 2, 1], [2, 1, 0]]
\$\endgroup\$
3
  • \$\begingroup\$ Why does it matter that the array is othogonal? \$\endgroup\$
    – pajonk
    Feb 12 at 7:12
  • \$\begingroup\$ @pajonk It doesn't, it was mostly because I didn't want to make things unnecessarily hard for langs like C and haskell which don't (natively) have ragged lists. You're right that almost all approaches would work for ragged lists, and I'm just going to change it to that. (sorry for the late reply) \$\endgroup\$
    – emanresu A
    Feb 15 at 20:38
  • \$\begingroup\$ Ah, sorry for the confusion. We have different definitions of orthogonal and array - for me an array is simply a non-ragged list and orthogonal is a specific property related to arrangement of columns in the array. That said, I personally would prefer non-ragged lists (arrays) in this challenge, as this would be easier for languages supporting matrices (and higher dimension generalisations) like R or Octave. \$\endgroup\$
    – pajonk
    Feb 16 at 5:44
1
\$\begingroup\$

Search the deepest depths of an array

Given a multidimensional array, find the length of the largest subarray that contains the depth of that subarray. The base array layer has a depth of 0.

Here is an example:

[1, 2, [3, 4, [2, 5]], 0]

Here, the subarray [2, 5] contains its own depth 2 and has a length of 2 as well.

But in the outermost subarray is a 0, its depth. The outermost subarray has a length of 4, which is greater than 2, so the output is 4.

Test Cases

[1, 2, [3, 4, [2, 5]], 0] => 4
[1, [2, 3], [[1]], [2, [2, 3]]] => 2
[1, 1, 1] => undefined (must not be a number >= 1)

  • Maybe it should be any subarray or the least nested one for some potential for solutions that aren't brute force?
\$\endgroup\$
1
  • \$\begingroup\$ "multidimensional array" is a bit of a confusing term here, it's really a ragged list/array. \$\endgroup\$
    – Wheat Wizard Mod
    1 hour ago
1
\$\begingroup\$

Swap letter cases

\$\endgroup\$
1
  • \$\begingroup\$ Why isn't this a dupe yet lol \$\endgroup\$
    – noodle man
    Feb 20 at 20:25
0
\$\begingroup\$

Test for Irreducible Complexity (Check for Redundant Characters)

I may need some additional help coming up with the full spec for this competition. As of right now, this is just a concept.

Many interesting questions, such as the "42" question in this sandbox, involve finding the longest program which is not reducible. This means that no set of characters can be removed and still allow the program to function as desired.

The basic idea is that your program will test a Base Program to make sure that it contains no redundant characters. The input will consist of:

  • Base Program (in the same language as your answer)
  • Expected Output

Your program will simply evaluate all possible subsequences of the Base Program and verify that none of them give the Expected Output.

This challenge actually has a utility value to several other challenges. For example, it verifies the results of a "longest non-reducible"-type challenge. In addition, it could make sure that a golfed solution cannot be golfed further.

I assume that the winning criteria will be fastest program, as cycling through all the possibilities takes a long time.

Problems

A sequence of length N has 2^N subsequences. Even if each evaluation is done very quickly, it might be unfeasible to test any program with more than 20 or so characters in a reasonable amount of time.

\$\endgroup\$
8
  • \$\begingroup\$ Problem: some subsequences of legitimate answers may be pretty dangerous to the environment. You don't want to eval just everything. \$\endgroup\$ Dec 23, 2013 at 16:59
  • \$\begingroup\$ @JanDvorak Yes that actually is a serious problem. To what extent is it possible to fix that? \$\endgroup\$
    – PhiNotPi
    Dec 23, 2013 at 17:04
  • 1
    \$\begingroup\$ Forbidding any program with dangerous subsequences? :-) \$\endgroup\$ Dec 23, 2013 at 17:05
  • 1
    \$\begingroup\$ A more reasonable (but very difficult) solution would be the requirement to implement a sandbox. \$\endgroup\$ Dec 23, 2013 at 17:07
  • 2
    \$\begingroup\$ Even without dangerous behavior, the halting problem will be an issue: it's hard to tell whether a shortened program will terminate at all, especially for every conceivable input. \$\endgroup\$
    – MvG
    Jan 7, 2014 at 23:49
  • \$\begingroup\$ Are you sure this is possible? The problem of testing if two functions/programs/turing-complete things are equivalent is undecidable - I'm fairly sure it's reasonable easy to constract a brainfuck program that you can't tell if you can remove even a single character. \$\endgroup\$ May 16, 2021 at 4:44
  • \$\begingroup\$ Extending on my previous comment - Let's assume you have a solution to this. Take a brainfuck program you want to test if halts. Let it reduce it, now you have an equivalent irreducible program. Add +. in the end of it, and then try to reduce it again. If the code never halts, that +. is reducible and when you'll run it again it will be removed. Otherwise it's important, so it will be kept. The halting problem is undecidable, therefor this is undecidable. \$\endgroup\$ May 16, 2021 at 4:54
  • \$\begingroup\$ You can also get its undecidablility from that in Unary it will tell you if a given program is minimal, which is known to be undecidable as well \$\endgroup\$ May 16, 2021 at 5:25
0
\$\begingroup\$

Wordlist detector

You are to write a program which, given a list of words, constructs a regular expression to match all these words but nothing else. Both your program and the constructed regular expressions are to be as short as possible.

Input and Output

Input comes on standard input and consists of one line giving n, the total number of words, followed by n lines with one word each. The number of words will be less than 1000, the length of each word less than 30. Words will consist only of lower case ASCII letters, i.e. a-z. You may choose to ignore the first line and use EOF instead to end the list.

Output shall be written to standard output. It consists of a single line, giving a POSIX extended regular expression to match these words and no others. Since input for this regex is not restricted to letters only, elements like . or [^…] won't make too much sense, which limits the language in a natural way. You may choose whether you want to terminate the line with a newline or not. Programs may choose to print multiple lines of output, in which case only the last one will be used for scoring. So you might print intermediate results and continue searching for improvements.

Test cases

Each submission may be accompanied by one regular expression. When scoring the submissions, I'll use this regular expression to reconstruct a word list from it. The code to do this reconstruction can be found at the end of this post. The reconstructed word list must fit the input specification above in terms of word count and length. It would be nice if your own program would be able to regenerate that regular expression from the word list, but that is not a strict requirement. But please don't paste bogus programs just to submit a challenging regular expression, though.

These test cases will be collected and fed to all programs for scoring.

Scoring

The final score of each program will be the program size plus the size of all its generated regular expressions for the inputs collected from submitted answers, including the example from this question. So short code which produces too long results might get beaten by longer code which generates shorter expressions.

Does this still qualify as ?

Submissions which generate an incorrect regular expression for one of the test cases will be disqualified, as will those which don't terminate in the allotted time. You can use the input reconstruction program below to check whether a produced regular expression does encode the correct word list.

Requirements

All submissions are welcome, but in order to include your submission in the tournament, it must be executable with reasonable effort on my Linux machine. It shouldn't depend on any exotic libraries, or any specialized ones which take too much work away from your own program. It must operate in reasonable time, say no more than five minutes per input. Your output must be reproducible, so if you use randomization at some point, please seed the randomizer, and please don't terminate an improove loop by a timer measuring execution time or some such.

Tournament times

I'll run the first major tournament two weeks after posting this question. I'll include a table of the results in this question. I'll try to run tournaments repeatedly as late submissions arrive, but I'll not promise any regular schedule.

Example

An very simple example application would be in Python 3 (53 chars):

print('|'.join(input() for i in range(int(input()))))

And here is a test case which could be posted along with the program, although this program obviously doesn't generate exactly this concise output:

bann?ana|ap(fel|ple)|s[ou]n|[hs](a|ou)nd

The expansion of that expression could be turned into the following example input, which need not be posted as part of an answer since it can be deduced from the regular expression:

10
banana
bannana
apfel
apple
son
sun
hand
hound
sand
sound

Regex expander program

And here is a program to turn regular expressions into word lists, again written in Python 3.

#!/bin/env python3
concat = set(('',))
altin = set(('',))
altout = set()
prev = None
stack = []
regex = iter(input())
for ch in regex:
    if ch == '(':
        stack.append((concat, altin, altout))
        altin = concat
        altout = set()
        prev = None
    elif ch == ')':
        concat.update(altout)
        prev, altin, altout = stack.pop()
    elif ch == '|':
        altout.update(concat)
        concat = altin
    elif ch == '[':
        ch = regex.__next__()
        cls = []
        while ch != ']':
            if ch == '-':
                crange = range(ord(cls[-1]), ord(regex.__next__()) + 1)
                cls.extend(map(chr, crange))
            else:
                cls.append(ch)
            ch = regex.__next__()
        prev = concat
        concat = set(w + c for w in prev for c in cls)
    elif ch == '?':
        concat.update(prev)
        prev = None
    elif ch >= 'a' and ch <= 'z':
        prev = concat
        concat = set(w + ch for w in prev)
    else:
        raise Exception("Illegal input")
if stack:
    raise Exception("Unclosed group")
concat.update(altout)
words = sorted(concat)
print(len(words))
print('\n'.join(words))

This is restricted to the part of regular expression syntax which I expect for this answer. If you have good reason to use something I did not consider, feel free to do so although I will likely have to update this code to cope with it. If you find a bug, please let me know.

\$\endgroup\$
1
  • 2
    \$\begingroup\$ This is just Meta regex golf under the constraint that the two lists between them cover all possible words. Given that some people are tackling that existing question on that basis, this would qualify for closing as a duplicate. \$\endgroup\$ Jan 8, 2014 at 8:45
0
\$\begingroup\$

Rhymalator

(at the point, it's just something that came to me before i wake up, so it may need some adjusting, and i'd like some feedback as to if this could be fun)


The code challenge is to write a program that takes as input a calculation in Reverse Polish Notation and outputs the result. It must at least implement + - * /. It So far so easy, but to make it fun and "artistic", the following restriction applies:

  • The source code must rhyme when read. Example in PHP

    $iterator = str_split($a);
    foreach ($iterator as $key=>$value){
        if ($key > 3){
            ++$virtue;
        }
    }
    

    (the rhyme is on value-virtue)

  • Lines whitout readable characters count as whitespace (the two lines with } in the example)

\$\endgroup\$
2
  • \$\begingroup\$ How does that example rhyme...? \$\endgroup\$
    – Doorknob
    Jan 25, 2014 at 12:54
  • \$\begingroup\$ @DoorknobofSnow well, i'm not really a poet, that's why i propose it as a challenge for others :p. if you have a better example i'll replace it \$\endgroup\$
    – Einacio
    Jan 27, 2014 at 15:58
0
\$\begingroup\$

Implement Kalah

The game of Kalah is a two-player board game in the Mancala family. Your implementation must:

  • Identify the active player ("Player 1" or "Player 2")
  • Display board state (in format specified below)
  • Accept input to allow that player to move (using index system below)
  • Announce a winner ("Player N wins")

Overview

Each player has a line of six spaces, called houses, and one additional space called a store. Each space holds seeds, which move from house to house in a counter-clockwise direction. The objective is to fill your store with seeds.

You must represent the board in the following two-row format with stores offset, where HH is a house and SS is a store:

SS HH HH HH HH HH HH
   HH HH HH HH HH HH SS

The top row represents the number of seeds in player #1's spaces, and the bottom row represents the seeds in player #2's spaces. The S in each row is the respective player's store (player #1's is top-left, #2's is bottom right). Single-digit values should include a leading space.

In this challenge, user-input will identify each house numerically. Use a left-to-right, indexed-from-one scheme for both sides:

S 1 2 3 4 5 6
  1 2 3 4 5 6 S

Note that the players' stores are not numbered, because seeds placed in the store never move out.

Rules

Wikipedia has a good summary of the game and its rules:

  1. At the beginning of the game, three seeds are placed in each house.

  2. Each player controls the six houses and their seeds on his/her side of the board. His/her score is the number of seeds in the store to his/her right. [Clarification: from our perspective, player 1's store is to the left, player 2's store is to the right.]

  3. Players take turns sowing their seeds. On a turn, the player removes all seeds from one of the houses under his/her control. Moving counter-clockwise, the player drops one seed in each house in turn, including the player's own store but not his/her opponent's.

  4. If the last sown seed lands in the player's store, the player gets an additional move. There is no limit on the number of moves a player can make in his/her turn.

  5. If the last sown seed lands in an empty house owned by the player, and the opposite house contains seeds, both the last seed and the opposite seeds are captured and placed into the player's store. [Clarification: moves that end on an opponent's empty house end normally without a capture.]

  6. When one player no longer has any seeds in any of his/her houses, the game ends. The other player moves all remaining seeds to his/her store, and the player with the most seeds in his/her store wins.

Example

(Parenthetical text should not appear in actual output.)

Player 1
 0  3  3  3  3  3  3
    3  3  3  3  3  3  0
> 2                      (prompt arrow and line break
                          are purely optional)
 Player 2
 1  1  0  3  3  3  3
    4  3  3  3  3  3  0
> 4

Player 2  (P2 gets a bonus turn from rule #4)
 1  0  3  3  3  3  3
    4  3  3  0  4  4  1
> 5

Player 1  
 1  0  3  3  3  4  4
    4  3  3  0  0  5  2
> 4

Player 1  (P1 captures P2's seeds in space 1)
 6  0  4  4  0  4  4
    0  3  3  0  0  5  2
...

Player 2
12  0  0 10  0  1  0
    0  0  0  0  0  1 13
 > 6

Player 1 wins            (because the non-finishing players gets
                          all remaining seeds on their side, it's 23-14)

Meta question: Would this be improved by removing some of the rules?

\$\endgroup\$
1
  • \$\begingroup\$ Do the players run the game once and then take it in turns to take moves, with the process ending only when the game ends? Or do they run the program once per move? \$\endgroup\$ Jan 30, 2014 at 10:06
0
\$\begingroup\$

[This is the first time I'm using the sandbox. I want to get feedback/suggestions before posting the question.]

Make a spider web (standard, orb type) that fills frame in the ratio of n:m, where n, m are input integers. You may use the example below as a model (but you don't need to use labels).

spider web

Your web should have multiple radii, at least 4 of which attach directly to the frame. The remaining radii should attach to the outer outline (perimeter) of the web. The web should have at least 15 radii. The mesh spacing should be more or less uniform spacing (although occasional weaving mistakes" or crossings are encouraged and will receive a bonus).

This is code-golf, so the shortest code (minus bonuses) wins.


Bonuses (to be removed from the number of characters in your code). Bonuses are awarded for the following features that reflect the architecture of an actual web (as opposed to a perfectly symmetric rendering). They are somewhat greater than usual as an incentive for attention to detail and realism.

-mesh spiral instead of concentric circles: 40 pts

-assymmetric web: 31 pts. (e.g. height of capture area greater than width)

-irregularly spaced radii: 42 pts

-distinct segments between radii (straight or crooked, but not the arc of a circle): 32 pts

-outer and inner outline clearly distinct from the spiral: 41 pts

-irregular outer outline: 20 pts

-2 or more easily observable reverses in spiral: 40

The accept will be awarded on Feb. 20, 2014.

\$\endgroup\$
2
  • \$\begingroup\$ If there are bonuses then it isn't code-golf, by definition. It's not clear what output formats are acceptable. I'm not sure what you mean by "distinct segments between radii". "2 or more easily observable reverses" seems problematic: the ease of observing reverses is subjective, and might in addition depend on input and/or on the random numbers obtained. The weighting for the bonuses seems very arbitrary: is there any justification for it? \$\endgroup\$ Feb 3, 2014 at 11:49
  • \$\begingroup\$ Re: bonuses, I should probably decide on the features I want included in the web, thereby eliminating bonuses altogether. Distinct segments means that there should be 2 straight mesh segments between radius n and radius n+2 (not sure whether this should be required in instructions to be updated.) Will give reverses more thought. \$\endgroup\$
    – DavidC
    Feb 3, 2014 at 12:02
0
\$\begingroup\$

Write a PHP Code Golfer

Since my currently daily programming is in PHP, I tend to try the challenges on the site using that language, but frequently I large program because of the verbosity of the language. And then I have to strip it for presentation...

But this is not a tips question, it's an eviscerating challenge.

The objective is to write a program in the language of your choice that takes a PHP file and outputs a golfed valid PHP file with the same functionality.

The scoring will be the average reduction in percent of the result of running the program with 3 selected files (not yet selected, I was thinking of some open source library)

The output file should run on at least 5.4 (so shorthand arrays, function dereference, traits are available)

Since the score is the difference between the ungolfed and golfed files, techniques beyond minifying are encouraged, such as using code subtitution, eval, compression, $$ (variable variables), dereferencing...


Scoring example: The 3 sources have 450, 1200 and 3500 chars respectively

Answer 1
results lenghts: 250, 1000, 3300
reduction: 200, 200, 200 (44%, 17%, 6%) average: 22%

Answer 2
results lenghts: 350, 1050, 3150
reduction: 100, 150, 350 (22%, 13%, 10%) average: 15%

In this case Answer 1 would win, even tough both answers got the same total reduction (-600 chars)

\$\endgroup\$
8
  • \$\begingroup\$ It's a specialisation of codegolf.stackexchange.com/q/3652/194 , so would likely be closed as a duplicate. \$\endgroup\$ Feb 4, 2014 at 22:44
  • \$\begingroup\$ @PeterTaylor I saw it. is similar, but I include an objetive goal and score. have any idea on how to make it more unique? \$\endgroup\$
    – Einacio
    Feb 5, 2014 at 2:43
  • \$\begingroup\$ "Making it shorter" is too broad, can I just delete some comments? If not, can I only shorten one variable and it's ok. It's not very interesting like this... \$\endgroup\$
    – Fabinout
    Feb 5, 2014 at 9:56
  • \$\begingroup\$ @Fabinout the objective is golfing the code. If you only remove some characters, I doubt you'll get a good score \$\endgroup\$
    – Einacio
    Feb 5, 2014 at 15:27
  • \$\begingroup\$ Alright, the criterion is the size of the output source code. good clarification. \$\endgroup\$
    – Fabinout
    Feb 5, 2014 at 15:55
  • \$\begingroup\$ Sum the bytes with the percents or separately? Also, no matter what sources you choose, make sure to paste the code into your questions; who knows when the code in the library will change? \$\endgroup\$
    – Justin
    Feb 6, 2014 at 19:11
  • \$\begingroup\$ i'll edit the bit about scoring (with examples) tomorrow (when i come back to work). I'll post the test sources as a pastebin, but I'll wait to choose them until the question is polished enough and someone consider it interesting enough \$\endgroup\$
    – Einacio
    Feb 6, 2014 at 19:34
  • \$\begingroup\$ Is there anyone more with questions? is still possible that it will be marked as a duplicate? or can i choose the sources and publish it? \$\endgroup\$
    – Einacio
    Feb 13, 2014 at 19:22
0
\$\begingroup\$

Create diagonal code

Your task is to create a program that outputs d=s*sqrt(2).

Specs:

  • Your program must be at least 4 lines long;

  • d=s*sqrt(2) cannot be hardcoded as is (so using ascii, compression, encoding, etc. is allowed and encouraged);

  • For each line of code n, pick up the nth character. The string obtained this way must be a valid program in a programming language of your choice, that must be different from the one you used for the main program. The obtained program must compile successfully, but it can throw errors, exceptions, etc.;

  • If at the nth line there is no nth character, you can consider that character as a whitespace or a newline. This cannot be done for the first 4 lines, which must be long at least n non-whitespace characters.

  • Your main program must end successfully (no errors, exceptions, etc.);

  • Internet access is forbidden;

  • Most upvoted answer in 2 weeks wins.

Happy coding!


I was unsure about making this a with several bonuses (polyglot answer, secondary program still valid, etc...).


Some bonuses for the code-challenge version:

Your valid answer starts with 0 points. You gain:

+10 if the secondary answer hides a third answer in it;
+15 for any other hidden answer;
+5 for every hidden answer that runs and ends successfully, without any problem;
+10 if your main answer is a polyglot;
+15 for every hidden answer that is a polyglot;


Which version would you prefer? Is there something you would change/improve in this question?

I personally like the one, but the KISS principle (Keep it simple, stupid!) reminds me that I may be wrong.

\$\endgroup\$
5
  • \$\begingroup\$ It's trivial to make the diagonal program be just whitespace (many scripting languages will accept this as a program) or H (valid program in H9Q+). \$\endgroup\$ Feb 26, 2014 at 9:26
  • \$\begingroup\$ Nowhere does it say that the diagonal program must output your magic string: it doesn't even have to execute correctly. Your amendment doesn't really fix things: I can now have the second line be #H, the third be #HH, etc. \$\endgroup\$ Feb 26, 2014 at 9:37
  • \$\begingroup\$ You're right; Don't know why, on a second read I messed up the meaning of your comment. Anyway, I suppose this excludes code-challenge unless I/we don't find a way to avoid such trivial solutions. I guess popularity-contest would still be ok, since more interesting solutions could be found, right? \$\endgroup\$
    – Vereos
    Feb 26, 2014 at 9:41
  • \$\begingroup\$ I think my views on popularity-contest in general are well known. On further reflection, there are enough languages in which any string of bytes is a valid program that I don't think this question can work as is. If you want to save it, I think you need to look at doing something like a very difficult double-quine. \$\endgroup\$ Feb 26, 2014 at 9:49
  • \$\begingroup\$ Thinking about quines and diagonals (which was the "spirit" of the question), what about a sort of mini-quine? The main program would have to display d=s*sqrt(2) only, and its diagonal must reproduce the code used to display the magic string (no comments allowed). It could be tagged code-golf or code-challenge. \$\endgroup\$
    – Vereos
    Feb 26, 2014 at 11:04
0
\$\begingroup\$

Create a Karnaugh-map calculator

Given an input of a truth table, generate a corresponding K-map.

Input:

Input will be of the form 10110001 where each bit is a row of a truth table. Count from the left to the right; so that input would be a table of:

i2i1i0 f
0 0 0|1
0 0 1|0
0 1 0|1
0 1 1|1
1 0 0|0
1 0 1|0
1 1 0|0
1 1 1|1

Max 4 variables will be inputted

K-maps (a small explanation):

K-maps are a way of simplifying boolean-algebra expressions.

Let's say we have 4 variables: a, b, c, d. Let the truth-table be 1110101001111111 (and the columns on the truth table be labeled, from left to right: a, b, c, d). Arrange the variables like so:

   cd
ab\   00 01 11 10
   00
   01
   11
   10

Note the grey-code counting scheme.

Fill in the table with the corresponding values from the truth table:

   cd
ab\   00 01 11 10
   00 1  1  0  1
   01 1  0  0  1
   11 0  1  1  1
   10 1  1  1  1

Group the values in rectangles whose dimensions are the largest possible powers of two. Note that this table signifies a torus, so wrap over the left and right edges.

enter image description here

The expression for the truth table is the ors of the and of the unchanging elements. For this, that would be:

Purple group: ¬b ∧ ¬c (for 0's, make them 1 by notting the value)
Green group: ¬a ∧ ¬d
Black group: a ∧ d
Blue group: b ∧ ¬d

Expression: (¬b ∧ ¬c) ∨ (¬a ∧ ¬d) ∨ (a ∧ d) ∨ (b ∧ ¬d)

Output:

  • Generate a 2D K-map (for more variables, add on either side) and show the grouping. K-map must be of the form I used. For less variables, remove rows or columns and change the list on the top left corner.
  • assume alphabetical ordering on the variables, that is, the first variable is a, second: b, third: c, and so on.
  • Also show the expression. Rather than use the unicode characters, the following is permissible:

    ~ instead of ¬
    * instead of ∧
    + instead of ∨
    


Edit: Possible duplicate: More fun with gates: Karnaugh simplification

\$\endgroup\$
8
  • \$\begingroup\$ I think the grouping is not unique and therefore I might choose the most basic grouping (i.e. none). \$\endgroup\$
    – Howard
    Feb 26, 2014 at 9:02
  • 1
    \$\begingroup\$ Although @Howard's concern is partially answered by "rectangles whose dimensions are the largest possible powers of two", it's not obvious to me why you haven't also circled the entire row 10 and the bottom-right quadrant. \$\endgroup\$ Feb 26, 2014 at 9:29
  • \$\begingroup\$ @PeterTaylor You're right - didn't read that line. But still my main concern is correct: it is not unique. Or as your remark shows it is not optimal if you choose all rectangles. \$\endgroup\$
    – Howard
    Feb 26, 2014 at 9:33
  • \$\begingroup\$ Also for higher number of variables you have to either go to n dimensional K-maps or you won't find all possible rectangles (they are no longer adjacent in the matrix). \$\endgroup\$
    – Howard
    Feb 26, 2014 at 9:38
  • \$\begingroup\$ @PeterTaylor In priority: Biggest rectangles, then least number. That is a big rectangle, but it is redundant with the others because every 1 in it is already circled. \$\endgroup\$
    – Justin
    Feb 26, 2014 at 16:44
  • \$\begingroup\$ @Howard Good point. I'll restrict it to 4 or less variables. \$\endgroup\$
    – Justin
    Feb 26, 2014 at 16:47
  • \$\begingroup\$ For the expression: rather than using A and V, why not * and +? That's fairly conventional use of field notation to represent GF(2). \$\endgroup\$ Feb 26, 2014 at 17:11
  • \$\begingroup\$ Ahem. OR is, of course, not the same as + in GF(2). But * and + is still the conventional notation for operations over the Boolean semiring. \$\endgroup\$ Feb 28, 2014 at 15:31
0
\$\begingroup\$

Title: Implement ROT-13... in ROT-13

Content:

Challenge: Implement ROT-13 in code that works as both itself and as the ROT-13 version of itself.

Scoring:

Your score is calculated as a percentage of used, ROT-13 eligible bytes in total of both versions of the program divided by total bytes (all characters) of both versions.

A used, ROT-13 eligible byte is any character that is not part of a comment or ignored by the compiler/interpreter. For example, any character in a brainfuck program that is not +-<>[],. is not considered a used byte, and any character in a C program including and after // or inside /* */ is not considered a used byte. All special symbols in APL are not considered used, as are all characters in a Whitespace program (sorry).

Example scoring:

C: 21/32 = 65.625%

main(){printf("Hello World!");}
\$\endgroup\$
3
  • \$\begingroup\$ Originally this question was ROT-47, not ROT-13. The rules are chosen so that choice of language doesn't easily determine the winner; otherwise, whitespace would easily win. When I changed it to ROT-13 I made only [A-Za-z] count so that a language like golfscript or brainfuck would not automatically score 100%. Looking for thoughts on how to capture the idea without making it too "choice of language" dependent. \$\endgroup\$
    – durron597
    Mar 3, 2014 at 21:13
  • \$\begingroup\$ Just saying, I have a C answer for the 47-version: qp.mniip.com/p/tz pick either of the lines \$\endgroup\$
    – mniip
    Mar 3, 2014 at 21:29
  • \$\begingroup\$ @mniip Okay I undeleted it :) \$\endgroup\$
    – durron597
    Mar 3, 2014 at 21:48
0
\$\begingroup\$

Convert input to ASCII Semaphore

With monitor resolutions getting higher and font sizes getting lower, a good programmer has to make efforts to ensure that output is accessible to the visually impaired. This can be problematic when the only display is in text. Toward this end, your assignment (if you choose to accept it) is to write a program that converts text input into ASCII art flag semaphore.

Input

  1. Your program must accept any letter in the ASCII character set from A to Z (case insensitive) and spaces.
  2. The program can accept input in any way that is convenient for the language it is written in (stdin, command line, file, etc.).

Output

  1. The program should output an ASCII art representation of the input string in flag semaphore. Follow this link to see the expected encoding.
  2. Line feeds and carriage returns should be interpreted as spaces.
  3. Numbers and other non-letters in the input may be ignored.
  4. You may use whatever ASCII art representation of the semaphore sender you like, but it must contain a person holding two flags and have distinct arms, legs, head, and flags. It must be at least 10x10 characters.
  5. Output may be either horizontal or vertical.

Example

Input: Hello

Output:

           ###
           ###
            #
 _____########
|  |       ###
|__|      ####
         # ###
        #  ###
       /   # #
      /\   # #
     /  \  # #
     \  /  # #
      \/  ## ##
                    /\
                   /  \
                  /\  /
                 #  \/
           ###  #
           ### #
            # #
          ####
         # ###
         # ###
         # ###
         # ###
         | # #
         |__ #
         |  |#
         |__|#
          ## ##
                    /\
                   /  \
                  /\  /
                 #  \/
           ###  #
           ### #
            # #
           ###
          ####
         # ###
        #  ###
       #   ###
      /    # #
     /\    # #
    /  \   # #
    \  /   # #
     \/   ## ##
                    /\
                   /  \
                  /\  /
                 #  \/
           ###  #
           ### #
            # #
           ###
          ####
         # ###
        #  ###
       #   ###
      /    # #
     /\    # #
    /  \   # #
    \  /   # #
     \/   ## ##
   /\
  /  \
  \  /\
   \/  #
        #  ###
         # ###
          # #
 _____########
|  |       ###
|__|       ###
           ###
           ###
           # #
           # #
           # #
           # #
          ## ##

Scoring

This is code golf. Shortest code wins.

\$\endgroup\$
8
  • \$\begingroup\$ define "easily recognisable". Would a simple 3x3 compass (say, with a head if not covered) do? say:.o. -|. /|. ; or even: ... xx. x.. (read by lines, dots represent spaces) \$\endgroup\$ Mar 6, 2014 at 20:16
  • \$\begingroup\$ @JanDvorak Good catch. Edited to include distinct items that must be present and a minimum size. I'm not exactly sure how to make that rule more clear. \$\endgroup\$
    – Comintern
    Mar 6, 2014 at 20:34
  • \$\begingroup\$ Define "person holding two flags". Is what I drew a person? Is this a (lying, due to formatting issues) person: o--? Are three x's on a vertical line a person? \$\endgroup\$ Mar 6, 2014 at 20:43
  • \$\begingroup\$ @JanDvorak Ack! had to many tabs open and forgot to save my edit. I think number 4 for output should cover that. \$\endgroup\$
    – Comintern
    Mar 6, 2014 at 20:47
  • \$\begingroup\$ Define "distinct arms, legs, head, and flags." But I suggest allowing very small figures as well, otherwise this will turn into a kolmogorov-complexity-like question with very little of the code actually involving generating a pair of directions. \$\endgroup\$ Mar 6, 2014 at 20:51
  • 2
    \$\begingroup\$ Very similar to this question. The ascii art is more complex here so perhaps it's not close enough to be called a duplicate... \$\endgroup\$
    – Gareth
    Mar 6, 2014 at 22:20
  • 2
    \$\begingroup\$ I disagree with @JanDvorak: I think this would be better with a fixed output spec which must be followed exactly. That way people can golf their code rather than the output. \$\endgroup\$ Mar 6, 2014 at 23:59
  • \$\begingroup\$ Standard figures seem best to me as well. If you demonstrate a full "clock" of hand positions for the standard figure, then you can require those as output. That's easier to assess than free reign for variations. \$\endgroup\$ Mar 7, 2014 at 0:14
0
\$\begingroup\$

With its strange choice of 9 different characters (plus space and newline), the ASCII art version of the FreeBSD logo has always looked to me as if it might be nicely formatted, obfuscated code is some programming language. (Is it?)

 ```                        `
s` `.....---.......--.```   -/
+o   .--`         /y:`      +.
 yo`:.            :o      `+-
  y/               -/`   -o/
 .-                  ::/sy+:.
 /                     `--  /
`:                          :`
`:                          :`
 /                          /
 .-                        -.
  --                      -.
   `:`                  `:`
     .--             `--.
        .---.....----.

Therefore I would like to challenge you to make it one: Either specify minimal changes to an existing programming language or minimal changes to this piece of ASCII art (making the artwork look different or significantly changing the character set used are definitely major changes), so that the logo, as source code generates meaningful output.

This should be a challenge, although I wouldn't mind some way of introducing hard scoring and run this as .

\$\endgroup\$
0
\$\begingroup\$

King of the Hill Fighting

In this game, a player controls 5 bots that attack the other players 5 bots. Each bot has life points, and has to reduce the other playres lifepoints to zero. This post is program that tests the controllers. It is in literate haskell.

> import Data.Set as S
> import Data.Map as M

Here is the arena:

    D---G
   /|   |\
  B |   | J
 /|\|   |/|\
A | E---H | L
 \|/|   |\|/
  C |   | K
   \|   |/
    F---I
20  12    4
  16    8   0

Positions are denoted by letters

> data Positions = A | B | C | D | E | F | G | H | I | J | K | L deriving (Show, Read, Eq, Ord)

Each player is presented a map in which their side is the one with A. Here is code that will reflect it so each player sees their own view.

> pairFlip = (\(x, y)->[(x,y), (y,x)])
> reflect = M.fromList $ [(A,L), (B,J), (D,G), (C, K), (E, H), (F, I)] >>= pairFlip

Lines denote connections.

> connections=S.fromList $
>   [(A,B), (A,C), (B,D), (C, F), (E, D), (E, F), (D, G), (E, H), (F, I)]
>   >>= pairFlip
>   >>= (\(x,y)->[(x,y), (reflect ! x, reflect ! y)])
> 
> connected x y=(x, y) `S.member` connections

The numbers below are the number of life points of generation that each bot.

> regen = M.fromList $
>   [ (A, 20), (B, 16), (C, 16), (D, 12), (E, 12), (F, 12)
>   , (G, 8), (H, 8), (I, 8), (J, 4), (K, 4), (L, 0)]
\$\endgroup\$
4
  • \$\begingroup\$ Is there supposed to be a specification hidden in here somewhere? \$\endgroup\$ Mar 14, 2014 at 16:30
  • \$\begingroup\$ @Peter Taylor Just not done yet. \$\endgroup\$ Mar 14, 2014 at 16:44
  • \$\begingroup\$ You won't get lots of answers if it's limited to Haskell. \$\endgroup\$
    – ugoren
    Mar 14, 2014 at 17:57
  • \$\begingroup\$ No no no, the above post is also a program for testing it. I will add in code that can take arbitrary programs and use them. \$\endgroup\$ Mar 14, 2014 at 21:17
0
\$\begingroup\$

Create the perfect CSS reset stylesheet

Your job is to create a CSS reset stylesheet, That is, a stylesheet that you can apply to any HTML file, and the result will look the same in all webbrowsers. Because we all know that cross-browser interoperability is very important these days, and you want to make your website look pixel perfect everywhere.

The rules:

  1. You must be able to throw any valid HTML5 document at it and the result will look the same in the main browsers.
    For simplicity, you can assume that the HTML document does not contain any styles of its own or Javascript that changes anything. Just pure, static HTML that is valid HTML5.
  2. The main browsers are Firefox >= 22, Chrome >= 28 and IE >= 10.
  3. To avoid solutions like *{display:none} (which do indeed make all documents look the same in all browsers, yes) the result must be identical to the document without the stylesheet in one of the browsers.
    In other words, take your browser of choice and make the document look like that in the other browsers.

The winner is the stylesheet that works the best, again, on any HTML file that is valid HTML5 and uses no other styles. I'm not looking at efficiency. If you come up with a 100K stylesheet or one that slows the site down considerably, that doesn't matter, as long as the end result looks good.


That's the question so far. Now I have a bit of a problem with "any HTML5 document"; I know I could provide a test document that people can work with, but then you'll get answers that cater to only that particular test case, and that's not what I want. Not sure how to handle this. Ideas?
Also, I want to include Safari as a main browsers, but as I don't have a Mac, I can't test the results on it. Not sure how to handle that.

\$\endgroup\$
7
  • \$\begingroup\$ necolas.github.io/normalize.css ? \$\endgroup\$ Mar 14, 2014 at 12:59
  • \$\begingroup\$ @PeterTaylor That breaks rule #3. \$\endgroup\$
    – Mr Lister
    Mar 14, 2014 at 13:05
  • \$\begingroup\$ The result must be identical to the document without the stylesheet in one of the browsers. I assume you have loaded a webpage without a stylesheet before? If you mean that it can have the main stylesheets, and we just need to create a modification stylesheet, you should specify that. \$\endgroup\$
    – user10766
    Mar 14, 2014 at 16:17
  • \$\begingroup\$ @hosch250 What I mean is that I want the document to retain its basic HTML-ness, so it shouldn't look like plain text. Take this fiddle for example; open it in all browsers, and then add CSS to it so that it looks like (your favourite browser) in all other browsers. If the name of such is "modification stylesheet" rather than "reset stylesheet", I apologise. \$\endgroup\$
    – Mr Lister
    Mar 14, 2014 at 19:32
  • \$\begingroup\$ OK, I was thinking about how most HTML pages rely on CSS stylesheets to even be legible. If you took the CSS sheet off any webpage, it would not look the same; in fact, if the HTML wasn't laid out good using accessibility techniques, it wouldn't be legible. \$\endgroup\$
    – user10766
    Mar 14, 2014 at 20:01
  • 2
    \$\begingroup\$ Pixel perfect isn't going to happen because of issues around anti-aliasing: CSS doesn't let you do things like enable ClearType on Safari/OS X or disable it on IE/Win. So the best anyone can do is somehow obtain the default stylesheets for the listed browsers (e.g. iecss.com but updated) and then find a minimal diff. \$\endgroup\$ Mar 14, 2014 at 20:09
  • \$\begingroup\$ Guys, I'm not interested in solutions to the question right now. I want to know if the question is OK! Specifically if I can get away with not posting a testcase like the fiddle above. \$\endgroup\$
    – Mr Lister
    Mar 14, 2014 at 20:38
0
\$\begingroup\$

music theory challenge

Create a program that takes some input in the form of frequency, waveform, and duration that generates an audio stream based on the input.

You can take input parameters however you choose, but if I input (translated to your method) 440Hz, sin(x), 3 seconds, your program should play or create a file for a sound 3 seconds long at 440 hertz on a sine wave.

Also, any output should be musically correct as far as frequency is concerned. See http://www.phy.mtu.edu/~suits/notefreqs.html for example frequencies

Since this is a popularity contest, the rest is up to you. I bid you Good programming!

Oh, and any use of external functions or APIs is ok, as long as they weren't developed specifically for this contest.

\$\endgroup\$
4
  • \$\begingroup\$ If the program takes "input in the form of frequency, waveform and duration" then where do linear functions fit? What do you mean "output should be musically correct as far as frequency is concerned" given that the input is frequency? Is it supposed to correct the input: "You said 494Hz but you must mean 493.88Hz"? And simple synth has been done before in various guises: see music. To differentiate this and make it non-trivial you could perhaps specify a set of basic synth operations which need to be configurable (e.g. input specifies generators, envelopes, filters, mixers). \$\endgroup\$ Mar 14, 2014 at 8:39
  • \$\begingroup\$ On second thoughts, that would probably work better as a Code Review Code Challenge \$\endgroup\$ Mar 14, 2014 at 9:23
  • \$\begingroup\$ @PeterTaylor I didn't even know about Code Review Code Challenges <intrigued>. Linear isn't the right word...and I think that statement is redundant anyway, so I'll nix it. \$\endgroup\$ Mar 14, 2014 at 12:44
  • \$\begingroup\$ Actually, I'm going to re-write this challenge...I don't know yet whether it'll be here of on CR \$\endgroup\$ Mar 14, 2014 at 13:07
0
\$\begingroup\$

Calculate pi using a unique method

Your task is to calculate or approximate pi using the most interesting method you know. Well-known things such as using inverse trig functions (asin, acos, atan) or commonly used convergent series are considered uninteresting.

You may calculate pi to any precision desired, but the more precision you can achieve, the better.

\$\endgroup\$
5
  • \$\begingroup\$ I couldn't find an exact duplicate of this, but I'd like to know if this overlaps too strongly with an existing question. \$\endgroup\$ Mar 14, 2014 at 18:51
  • \$\begingroup\$ If you rule out convergent series, what's left? \$\endgroup\$ Mar 14, 2014 at 20:02
  • \$\begingroup\$ @PeterTaylor If someone knows of a convergent series that isn't on Wikipedia, that would make a good answer. I know of an answer that does not use trigonometry or an approximation, but calculates the digits directly. \$\endgroup\$ Mar 14, 2014 at 20:08
  • \$\begingroup\$ Is it in mathworld.wolfram.com/PiFormulas.html ? I've got some ancient code which uses a spigot hypergeometric evaluator to compute pi as 3*F(1/2, 1, 1, 8/5 ; 3/5, 4/3, 5/3 | 2/27), but I would expect that to count as well-known. \$\endgroup\$ Mar 14, 2014 at 20:11
  • \$\begingroup\$ @PeterTaylor I'm familiar with it in layman's terms only, but I don't see it there. It could be related to some of them, but I don't see more than a small resemblance. It isn't original with me, BTW. \$\endgroup\$ Mar 14, 2014 at 20:22
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