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Answer 1

image-processingcode-challenge

Autonomous Vehicle

I need a brain for my self-driving car. Something that will take still frames from the front-facing camera and give the navigation system commands. Obviously, if my car is driving me somewhere, I don't want to stop. However, I also don't want to:

1. Kill someone
2. Die

Knowing myself, we can assume that:

• At the speed I drive, hitting the curb or otherwise leaving the road will kill me and thus violate Don't #2

• With my luck, running a stop light, will violate Don't #1 or #2 or both

• Also hitting a pedestrian (or another car) violates Don't #1 (and possibly #2)

Input

The program/function should take an image as input. How it does this is flexible.

Output

The program/function should output one of these commands; ideally, one of the commands that doesn't result in one of the Don'ts being violated.

╔═════════╤═══════════════════════════════════════════════╗
║ Command │ Navigational Outcome                          ║
╠═════════╪═══════════════════════════════════════════════╣
║ Forward │ No course correction, continue straight ahead ║
╟─────────┼───────────────────────────────────────────────╢
║ Left    │ Veer left                                     ║
╟─────────┼───────────────────────────────────────────────╢
║ Right   │ Veer right                                    ║
╟─────────┼───────────────────────────────────────────────╢
║ Stop    │ Screech to a grinding halt                    ║
╚═════════╧═══════════════════════════════════════════════╝

Specifications

• Take an image as input in someway
• Output a command [ Forward, Left, Right, Stop ]
  • Commands can be aliased as [ 0, 1, 2, 3 ] respectively
  • Returning one valid command and no invalid commands is sufficient to pass a test
  • Stop is only valid iff every other command would violate one of the Don'ts
• Rules for valid commands:
  • No running stop lights
  • No running over people
  • No running into vehicles
  • No running off the road
  • If a command does not violate any of the above, then it is valid
• Program/Function must be deterministic

Scoring

Lowest score wins! The scoring function is:

• ( # of Bytes ) / ( Number of Passed Tests )

For example, a 450 byte Python solution that passes 2 test cases earns a score of 450 / 2 or 225.

---

Test Cases

1. Valid Commands: Forward

2. Valid Commands: Left, Right

   • Straight ahead there are pedestrians crossing

3. Valid Commands: Forward, Right

4. Valid Commands: Forward

5. Valid Commands: Left, Right

6. Valid Commands: Stop

Answer 2

Embed a graph into the Rado graph

The Rado graph is an infinite undirected graph whose vertices are labelled with natural numbers {0, 1, 2, ...}.

The edge (i,j) with i<j is in the graph whenever the binary expansion of j has a 1 in its ith place. Here, place values are counted from the end, with the 0'th place being the least significant bit. In terms of bitshifts, this means (j>>i)&1==1.

The Rado graph is universal in that any finite graph is a subgraph of it. This means that any finite graph can be embedded in the Rado graph: to each vertex of the finite graph, assign a distinct vertex of the Rado graph so that any two vertices of the original graph have an edge if and only if the corresponding vertices of the Rado graph have an edge.

Your task is to output such an embedding for a finite graph given as input.

TODO: Lots of stuff

Answer 3

Draw Concentric Squarephabets

code-golf kolmongrov-complexity ascii-art

Challenge

Write a program or function that, given an input integer n, outputs a concentric squarephabet of size n×n.

A concentric squarephabet is an ASCII-art square of concentric rings, where the outside ring of characters are As, the second Bs, the third Cs, etc. For example, a 25×25 squarephabet looks like this:

AAAAAAAAAAAAAAAAAAAAAAAAA
ABBBBBBBBBBBBBBBBBBBBBBBA
ABCCCCCCCCCCCCCCCCCCCCCBA
ABCDDDDDDDDDDDDDDDDDDDCBA
ABCDEEEEEEEEEEEEEEEEEDCBA
ABCDEFFFFFFFFFFFFFFFEDCBA
ABCDEFGGGGGGGGGGGGGFEDCBA
ABCDEFGHHHHHHHHHHHGFEDCBA
ABCDEFGHIIIIIIIIIHGFEDCBA
ABCDEFGHIJJJJJJJIHGFEDCBA
ABCDEFGHIJKKKKKJIHGFEDCBA
ABCDEFGHIJKLLLKJIHGFEDCBA
ABCDEFGHIJKLMLKJIHGFEDCBA
ABCDEFGHIJKLLLKJIHGFEDCBA
ABCDEFGHIJKKKKKJIHGFEDCBA
ABCDEFGHIJJJJJJJIHGFEDCBA
ABCDEFGHIIIIIIIIIHGFEDCBA
ABCDEFGHHHHHHHHHHHGFEDCBA
ABCDEFGGGGGGGGGGGGGFEDCBA
ABCDEFFFFFFFFFFFFFFFEDCBA
ABCDEEEEEEEEEEEEEEEEEDCBA
ABCDDDDDDDDDDDDDDDDDDDCBA
ABCCCCCCCCCCCCCCCCCCCCCBA
ABBBBBBBBBBBBBBBBBBBBBBBA
AAAAAAAAAAAAAAAAAAAAAAAAA

(and yes I typed that by hand ☺)

If the input is an even number, the centre of the squarephabet will be a 2×2 square instead of a single letter. For example, for input 8:

AAAAAAAA
ABBBBBBA
ABCCCCBA
ABCDDCBA
ABCDDCBA
ABCCCCBA
ABBBBBBA
AAAAAAAA

Specification

• Standard loopholes are forbidden.
• The input to your program or function will never be less than 1 or greater than 52 (26×2). This means you do not have to deal with letters after Z.
• You may output uppercase or lowercase letters, but you must be consistent in your choice.

Test Cases

Format:

Input
Output

Test cases:

1
A

2
AA
AA

3
AAA
ABA
AAA

10
AAAAAAAAAA
ABBBBBBBBA
ABCCCCCCBA
ABCDDDDCBA
ABCDEEDCBA
ABCDEEDCBA
ABCDDDDCBA
ABCCCCCCBA
ABBBBBBBBA
AAAAAAAAAA

25
AAAAAAAAAAAAAAAAAAAAAAAAA
ABBBBBBBBBBBBBBBBBBBBBBBA
ABCCCCCCCCCCCCCCCCCCCCCBA
ABCDDDDDDDDDDDDDDDDDDDCBA
ABCDEEEEEEEEEEEEEEEEEDCBA
ABCDEFFFFFFFFFFFFFFFEDCBA
ABCDEFGGGGGGGGGGGGGFEDCBA
ABCDEFGHHHHHHHHHHHGFEDCBA
ABCDEFGHIIIIIIIIIHGFEDCBA
ABCDEFGHIJJJJJJJIHGFEDCBA
ABCDEFGHIJKKKKKJIHGFEDCBA
ABCDEFGHIJKLLLKJIHGFEDCBA
ABCDEFGHIJKLMLKJIHGFEDCBA
ABCDEFGHIJKLLLKJIHGFEDCBA
ABCDEFGHIJKKKKKJIHGFEDCBA
ABCDEFGHIJJJJJJJIHGFEDCBA
ABCDEFGHIIIIIIIIIHGFEDCBA
ABCDEFGHHHHHHHHHHHGFEDCBA
ABCDEFGGGGGGGGGGGGGFEDCBA
ABCDEFFFFFFFFFFFFFFFEDCBA
ABCDEEEEEEEEEEEEEEEEEDCBA
ABCDDDDDDDDDDDDDDDDDDDCBA
ABCCCCCCCCCCCCCCCCCCCCCBA
ABBBBBBBBBBBBBBBBBBBBBBBA
AAAAAAAAAAAAAAAAAAAAAAAAA

52
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
ABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBA
ABCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCBA
ABCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCBA
ABCDEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEDCBA
ABCDEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEDCBA
ABCDEFGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGFEDCBA
ABCDEFGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHGFEDCBA
ABCDEFGHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHGFEDCBA
ABCDEFGHIJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJIHGFEDCBA
ABCDEFGHIJKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKJIHGFEDCBA
ABCDEFGHIJKLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLKJIHGFEDCBA
ABCDEFGHIJKLMMMMMMMMMMMMMMMMMMMMMMMMMMMMLKJIHGFEDCBA
ABCDEFGHIJKLMNNNNNNNNNNNNNNNNNNNNNNNNNNMLKJIHGFEDCBA
ABCDEFGHIJKLMNOOOOOOOOOOOOOOOOOOOOOOOONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPPPPPPPPPPPPPPPPPPPPPPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQQQQQQQQQQQQQQQQQQQQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRRRRRRRRRRRRRRRRRRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSSSSSSSSSSSSSSSSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTTTTTTTTTTTTTTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUUUUUUUUUUUUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVVVVVVVVVVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWWWWWWWWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWXXXXXXWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWXYYYYXWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWXYZZYXWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWXYYYYXWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWXXXXXXWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVWWWWWWWWVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUVVVVVVVVVVUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTUUUUUUUUUUUUTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSTTTTTTTTTTTTTTSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRSSSSSSSSSSSSSSSSRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQRRRRRRRRRRRRRRRRRRQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPQQQQQQQQQQQQQQQQQQQQPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOPPPPPPPPPPPPPPPPPPPPPPONMLKJIHGFEDCBA
ABCDEFGHIJKLMNOOOOOOOOOOOOOOOOOOOOOOOONMLKJIHGFEDCBA
ABCDEFGHIJKLMNNNNNNNNNNNNNNNNNNNNNNNNNNMLKJIHGFEDCBA
ABCDEFGHIJKLMMMMMMMMMMMMMMMMMMMMMMMMMMMMLKJIHGFEDCBA
ABCDEFGHIJKLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLKJIHGFEDCBA
ABCDEFGHIJKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKJIHGFEDCBA
ABCDEFGHIJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJIHGFEDCBA
ABCDEFGHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHGFEDCBA
ABCDEFGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHGFEDCBA
ABCDEFGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGFEDCBA
ABCDEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEDCBA
ABCDEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEDCBA
ABCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCBA
ABCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCBA
ABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

Scoring

This is code-golf, so shortest answer wins. Good luck!

Answer 4

A meander is a self-avoiding closed curve which intersects a line a number of times.

Your task is, given a self-avoiding walk on a lattice/grid, produce a meander a la the following:

Input

{{{3, 4}}, {1, 2}, {2, 6}, {6, 7}, {7, 3}, {3, 4}, {4, 8}, {8, 12}, {12, 11}, {11, 10}, {10, 9}, {9, 5}, {5, 1}}

Output

or similar.

Test cases:

Inputs

a={{{3, 5}}, {{1, 2}, {2, 3}, {3, 8}, {8, 9}, {9, 4}, {4, 5}, {5, 10}, {10, 15}, {15, 14}, {14, 13}, {13, 8}, {8, 7}, {7, 12}, {12, 11}, {11, 6}, {6, 1}}}
b={{{3, 6}}, {{1, 2}, {2, 8}, {8, 9}, {9, 3}, {3, 4}, {4, 10}, {10, 11}, {11, 5}, {5, 6}, {6, 12}, {12, 18}, {18, 17}, {17, 16}, {16, 10}, {10, 9}, {9, 15}, {15, 14}, {14, 13}, {13, 7}, {7, 1}}

Output

In the above examples, the numbers correspond to a grid, bottom to top, left to right, so 1 is bottom-left, and 18 on a 3*6 grid is top-right. The orientation of your grid doesn't have to follow this order: it can have any desired orientation.

You can assume dimensions of the grid are given at the begining of the input, as per the obove examples.

Feel free to use either pre-existing images - eg

or generate your own. This is Code Golf, so the shortest answer in bytes wins.

Answer 5

THIS A QUESTION IN PROGRESS

ASCII Art converter

see ASCII Art on Esolangs

Your task is to take input of a brainf*** program and output its equivalent ASCII art program. Your challenge: You may not use the following symbols in your program: \ / - | _ # Standard loopholes not allowed...

This is a code-golf so shortest answer in bytes wins

OR

ACII Art Interpreter

Your task is to create an interpreter for the ASCII art language. ASCII Art is a variant of brainf*** where characters are instead ASCII art figures 5 lines tall.

< looks like

 /
/
\
 \

> looks like

\
 \
 /
/

+ looks like

  |
  |
-----
  |
  |

- looks like

-----

[ looks like

____
|
|
|
|___

] looks like

____
   |
   |
   |
___|

. looks like

##
##

, looks like

##
##
_|

Characters that are less than 5 characters tall may be placed anywhere within the top line and bottom line of input.

____________________ top line
     \
      \
      /
     /
        <--- gap because this char is only 5 characters tall
_____________________bottom line

There may be any amount of white space between characters. Also characters can be "nested" in each other, as long as they do not touch. EG

____ |  ##
|    |  ##
|  -----_|
|    |
|___ |

is perfectly valid

Your code should not allow improperly formatted ASCII art, and should print to Standard error. For example, the following code should not work

\
 \
  |
  |
  |____

This is a code-golf, so the shortest answer in bytes wins!
Additional tags: interpreter ascii-art

Answer 6

Find the Watermark

At the moment, I don't have time to outline this properly. The idea is simple: Find the watermark in an image. The implementation, however, is obviously not simple. Since watermarks can have a variety of characteristics, I'd like to admit a variety of answer styles and make it a popularity-contest. Some ideas for the output format:

• Return coordinates of the (centre|corner(s)?) of the watermark
• Return a line in some form (e.g., endpoints or equation) that runs through the watermark
• Return an image that contains only a mask matching the watermark

Input, obviously, would be an image containing a watermark. Images without watermarks are not valid input; as such, submissions do not need to handle them in any special way.

graphical-output

Answer 7

whispering and SHOUTING

code-golf

Typing in all caps on the internet is often called "shouting". For the sake of this challenge, I'll call typing in all-lowercase "whispering".

The challenge

Write a complete program that can be run in two different ways: whispering and shouting. The "whispering" version of the program must be written in all-lowercase characters, and it should print whisper to STDOUT. The "shouting" version of the program will print SHOUT. The shouting version must be the exact same program as the whispering version, but with all lowercase letters replaced by the uppercase version of the letter. Everything else must be identical.

Rules

• No standard loopholes
• This is code-golf, so shortest program in bytes wins!

Answer 8

Switching lines

Let's say you have a string of text:

Hello, World! Today is a
most glorious day. In fact,
it's another day. Woohoo!

This string has three lines. We can call them lines 1, 2, and 3. (Or, if you prefer zero-indexing, lines 0, 1, and 2. I'll be using one-indexing to describe this challenge.)

Let's also say we have a mapping of line numbers to line numbers, such as 1 => 2, 3 => 1, 2 => 3. We will interpret this mapping as a method of "switching" lines with each other; the first rule switches line 1 with line 2, then line 3 with line 1, then line 2 with line 3. This would make the string look like, with intermediate steps:

Rule: (initial)
1. Hello, World! Today is a
2. most glorious day. In fact,
3. it's another day. Woohoo!

Rule: 1 => 2
2. most glorious day. In fact,
1. Hello, World! Today is a
3. it's another day. Woohoo!

Rule: 3 => 1
2. most glorious day. In fact,
3. it's another day. Woohoo!
1. Hello, World! Today is a

Rule: 2 => 3
3. it's another day. Woohoo!
2. most glorious day. In fact,
1. Hello, World! Today is a

Notice how the rule describes lines to be switched, not merely lines in that index. So each line has a permanent, associated line number.

Any rule such as 1 => 1 is effectively a no-operation.

Objective Given a list of numbers in any convenient format (e.g. an array of pairs of integers, a list like A B\nC D, a list of numbers, etc.) and a non-empty string of text, perform the action described above.

---

Meta

is it a good idea to do line identity instead of line locations?

Answer 9

Tweetable Video

code-challenge printable-ascii compression image-processing

This challenge is inspired by the Encode Images into Tweets challenge, extending the idea to now attempt to compress video into a series of "tweet" sized messages where the number of tweets == number frames of the video.

The competition is to compress 450 frames of video into 450 (or less) tweets of 140 charactes ( 114.97 bytes per tweet, total max 51737 bytes).

Original frames as Video, as PNG images [Sandbox note: Higher quality version will be uploaded soon]

Reference solution frames as Video [Sandbox note: Reference solution will be expanded once challenge changes stabilized]

Rules:

These rules are the based from rules in Encode Images into Tweets modified to accommodate multiple frames that will yield the resultant video.

1. You must write a program that will communicate via std in/out based on the communication protocol defined below, ultimately producing a series of tweets that will, when fed back to your program, produce image frames of the video.
2. The text created for each 'Tweet' by the program must be at most 140 characters long and must only contain characters whose code points are in the range of 32-126, inclusive.
3. The source video will be 450 frames of Big Buck Bunny. Frames can be downloaded here
4. Frames will be width 320 pixels and height 240 pixels @ 24 bit RGB, each channel having 8 bit precision.
5. Your program should be able to compress other video sources at same resolution.
6. Your program can use external libraries and files, but cannot require an internet connection or a connection to other computers.
7. The decoding process cannot access or contain the original images in any way. (Clarification use of corpus images is allowed as long as these images do not contain direct or manipulated original image frames)
8. Use of video codecs or existing libraries that perform video compression are not allowed. This is to encourage experimentation and originality rather than simply calling libraries. Note that use of static image compressors/ libraries are allowed.
9. Standard Loopholes are forbidden.

Communication Protocol

1. All communication is via std in/out.
2. The controller program will launch your program with no command line arguments.
3. The controller will either initiate a one of the following sequences commanding to your program and expecting results.

Note the sequences are described below in the following format:

<Comms direction from controller perspective>, <seq number>: <Transmitted Data> - <Information> 

For Encoding of the frames:

Output, 1: ENCODE\n - Indicating that the controller will be sending frames for your program to compress.
Output, 2: <number of frames>\n - String indicating number of frames. i.e. 450
Output, 3: <number of bytes for image data>\n - String indicating number of bytes of the current image data. e.g. 32145
Output, 4: <image data> - sequence of bytes of length defined in output line 3. The is the image data. The image data is a 24 bit image in PNG format
Repeat from output seq number 3 for the number of frames in output seq number 2.
Input, 1: <Tweet>\n - encoded image data. upto 140 characters, whose code points are in the range of 32-126, inclusive. A zero sized tweet will indicate end of all tweets.
Repeat from input line 1 for 1 to up to the number of frames in output seq number 2. Note a zero sized tweet will indicate end of all tweets.
Output, 5: END\n - Indicating that all processing has finished and your program should quit gracefully.

For Decoding of the frames:

Output, 1: DECODE\n - Indicating that the controller will be sending tweets for your program to decompress.
Output, 2: <number of tweets>\n - String indicating number of tweets. i.e. 450
Output, 3: <Tweet>\n - encoded image data. upto 140 characters, whose code points are in the range of 32-126
Input, 1: <number image frames decoded>\n - String indicating number of image frames that have been decoded as a result of the provided tweet. If 0 then no images have been decoded for this tweet.
Input, 2: <number of bytes for image data>\n - String indicating number of bytes of the current image data. e.g. 32145.
Input, 3: <image data> - sequence of bytes of length defined in input line 2. The is the image data. The image data is a 24 bit image in PNG format. 
Repeat from input seq number 2 for the number of frames in input seq number 1.
Repeat from output seq number 3 for the number of tweets in output seq number 2.
Output, 4: END\n - Indicating that all processing has finished and your program should quit gracefully.

4. Your program will be restart between the encoding and decoding phases.

Scoring

As an attempt to model the human visual system in a simplistic manner, JPEG quality levels are used as an analogue. Each frame will be compressed to a JPEG using quality levels 0.01 to 1.0 in 0.01 increments. The PSNR of these JPEG compressed versions are calculated and added into a data structure. Additionally, each frame will be resized by half and the JPEG encoding and PSNR calculations performed and added to the data structure. The resizing and calculating will repeat until a single pixel is left.

The result of which will be a scoring continuum of visual 'quality' from low (single color frame) to High (near-identical to original).

Thus, scoring will be objective by means of the following formula:

JPEG_QUALITY_LEVEL_PSNR = a pre-computed data multi dimensional structure consisting of the
                          PSNR for incremental JPEG quality levels for each image frame of
                          the video. The entries into this structure for each frame is such
                          that higher indecies are deemed to be of more similar to the
                          original.

Score = SUM of (index of closest matching entry in JPEG_QUALITY_LEVEL_PSNR for given
                original frame and given PSNR of decoded frame)

Controller

[Sandbox note: Controller is to be created]

Refrence Solution

[Sandbox note: Reference is to be created once question stabilizes]

Sandbox Questions

Ok, so this is my first question ever posed to codegolf and I am very keen to get feedback on how to better present the challenge.

Some areas where I would like specific feed back is the objective scoring mechanism... i purposely avoided direct PSNR as the score as it is very limited for scoring video quality, being biased toward blurry images, however other algorithms are too complex or not defined. So as a compromise I am using JPEG compression as an analogue for the Human Visual System. Effectively matching a given solutions output frame to original frame PSNR to a JPEG compressed, at a given quality level) version's PSNR and using that match's index in sorted JPEG quality order as input for the score.

Is the protocol clear enough? if not what would be a better way to present it?

Answer 10

code-golf string math number

Interpret MSF-!

Because there aren't enough "Interpret X" challenges.

MiniStringFuck (or MSF-) is a brainfuck derivate made by @ErikTheGolfer, with two commands, operating on one cell:

InstructionAction                                                                               
+               Increment the memory cell. If it reaches 256, wrap to 0.
.                Output the character in the cell.                                      

or a bad-looking table:

Instruction, Action
+, Increment the memory cell. If it reaches 256, wrap to 0.
., Output the character in the cell.

---

Task

Your task is to, given a string of MSF- code, containing only printable ASCII characters, output what it would print.

The string may have other characters than + and .. Treat them as NOPs

Example

++++++++++++++++++++++++++++++++++++++++++++++++.+.+.+.+.+.+.+.+.+.
++++++++++++++++++++++++++++++++++++++++++++++++.                    Set cell to 48 (0) and output
                                                 +.+.+.+.+.+.+.+.+.  Keep adding and outputting until 57 (9)

Test Cases

+++++++++++++++++++++++++++++++++.+.+. -> !"#
++++++++++++++++++++++++++++++++++++++++++++++++.+.+.+.+.+.+.+.+.+. -> 0123456789
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+.+. -> ABCDEFGHIJKLMNOPQRSTUVWXYZ
ABCDEFGHIJKLMNOPQRSTUVWXYZ -> (no output)

Answer 11

Interleave your code with the input

Given an input string, interleave this string with the source code of your solution.

For example, if your code is abcd and the input is 1234, then your program must output 1a2b3c4d.

If your code is shorter than the input, then it must loop back to the beginning of your code. For example, if your code is abcd and the input is 123456, then your program must output 1a2b3c4d5a6b.

If your code is longer than the input, then only part of your code will be interleaved with the input. For example, if your code is abcd and the input is 12, then your program must output 1a2b.

Inputs and outputs

• The input string will only contain characters which are valid string characters in your language.

• The input may be taken through STDIN, as a function argument, or anything similar.

• The output may be printed to STDOUT, returned from a function, or anything similar.

Scoring

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

Answer 12

Priority to the right

Your task is to regulate traffic on a crossroads. There are 4 roads coming from north, east, south and west.

The input is a string representing the upcoming traffic on each road. For example, NNNWS indicates there is a total of 5 cars: three at the north, one at the west and one at the south. The order has no importance here, NNNWS is equivalent to WNNSN.

You must output the order in which the cars should go, using the priority to the right rule: cars coming from the south must let cars coming from east go first, east gives way to north, north gives way to west and west gives way to south.

For example, with the input NNNWS, the south car should go first, then the west car, then the 3 north cars. The output should then be SWNNN.

There are some indecidable cases, for example NS or NNWSE : you should then output the string stuck.

Test cases

N => N
NW => WN
NWS => SWN
SNW => SWN
SSSSS => SSSSS
ENNNNES => NNNNEES
NS => stuck
NNWSE => stuck

Answer 13

golf.ko - Kernel module golf

code-golf

A Linux-specific challenge.

Implement a Linux kernel module which printks Hello world upon loading, in some compiled language.

---

Source file, linker scripts and command lines, Makefile content (if any) are all counted towards the byte score.

You may expect kernel version to be 4.1 or 4.4.

The kernel is assumed to be running. It's built, not cleaned source code is assumed to reside in /usr/src/linux. In addition you may expect the system to be Debian and to have working DKMS.

Answer 14

Random Quine

quine (something related to languages?)

You are to write N programs in N langauges (at least 2) that satify the following properties:

1. For each program P, the program P must produce an output O that is equal to a random program Q that you wrote, including P.
2. No two programs P and Q may be equal.

Let's say you have two programs, ABCD in language Bar and 1234 in language Baz. Then, ABCD must produce each of ABCD and 1234 with nonzero (but not necessarily equal) probability. Similarly, 1234 must output ABCD or 1234 with nonzero chance. Note that the chances do not have to be same for each program.

Answer 15

---

Introduction

The challenge is to determine if two complex lines intersect.

Challenge

Given two lines made up of multiple straight line segments determine if the lines cross at any point.

Input can be in the format of you choice that takes a series of [x,y] coordinates. All coordinates will be integers (positive or negative)

Output will be truthy if the lines cross and falsey if they don't cross.

There will be no coincidental points and no segment of one line will terminate at a point touching the other line (there will be a clean cross of line segments if the case is truthy).

This is code golf so shortest answer wins

Example Input and Output

For the examples formats are given as

Line 1: [[X1,Y1],[X2,Y2]...,[Xn,Yn]] Line 2: [[X1,Y1],[X2,Y2]...,[Xn,Yn]]

Examples

Line 1: [[0,0],[1,1]] Line 2: [[0,1],[1,0]] = TRUE

Line 1: [[2,2],[1,0],[0,2]] Line 2: [[0,1],[1,1]] = TRUE

Line 1: [[1,3],[2,9],[3,6],[4,7],[5,4],[6,1]] Line 2: [[2,6],[3,5],[5,2]] = FALSE

Line 1: [[0,6],[3,8],[5,5],[8,5]] Line 2: [[0,4],[3,7],[5,4],[7,6]] = TRUE

Line 1: [[2,2],[3,2]] Line 2: [[1,1],[10,4]] = FALSE

Please let me know your thoughts, first puzzle.

Answer 16

Raytracing/Raycasting

Here is a 256*256 heightmap. Your challenge is to render it, in minecraft-style blocks, using some form of raytracing.

Fundamental Definitions And Clarifications

These are all straightforward and fairly obvious but I'm being explicit so that what follows is (ideally) unambiguous.

• Let each pixel represent 1x1 metre, for ease of thought.
• This image is a top-down view. The bottom-left pixel of the image in screen space is at [0,0,0] in world space. The bottom-right pixel of the image in screen space is at [255,0,0] (i.e. the next full tile to the right would be anchored at [256,0,0]). The Z-axis increases away from us in world space so the top-left pixel is at [0,0,255] and the top-right-pixel is at [255,0,255].
• As you are looking down to the floor at the moment, you have positive height and the vector from your eye to the image points in the direction of [0,-1,0], so the camera which corresponds to the above image has a world-space coordinate of something like [128,300,128].
• It shouldn't really matter, but let's take the red channel as holding the height. A red channel value of foo puts that pixel at y=foo. The tallest possible pixel would have world coordinate [x,255,z] with 0<=x,z<256.

Aesthetic Definitions

• Each pixel effectively represents a tower some number of 1x1x1 solid cubes. The edges of these blocks should be rendered sharply at 90-degree angles. If you were to convert this scene to triangles, each normal would be along one of the major axes. You can think of blocks having end-caps on their top (which is the floor, to us), and walls are extruded between neighbouring blocks as required. There are no holes in the rendered surface. You can assume all renderings will be from above (extra implied geometry below the floor doesn't matter).
• As well as the heightmap, the world contains one camera and one light source. The light casts hard shadows, so every rendered pixel will require two ray casts. Light falloff is inverse-square. You may optionally gamma-correct the result.
• Pixels on a surface which receive no light should be black. Pixels of rays which do not hit any surface should be magenta: rgb=(255,0,255).

Input Parameters

• The camera is defined by position P=[px,py,pz], a T=[tx,ty,tz] target point, and a field of view FOV. It renders WIDTH x HEIGHT images such that the target point appears in the centre.
• The camera is orientated such that it yaws, then pitches, but does not roll.
• The light is at position L=[lx,ly,lz] and casts light uniformly in all directions.
• You solution must be posted with reference image rendered with P=[80,256,0], T=[128,50,200], L=[256,300,128], WIDTH=400, HEIGHT=300 and FOV=45 degrees.
• (As reference images emerge I might tweak these parameters.)

Free Parameters

• The light can be any colour and brightness you like but the colour and brightness must be inputs to the program.
• Likewise, the colour/material of the surface may be anything you like (except magenta, which is for revealing holes) but these colour/material parameters must be an adjustable input to the program.
• Use any lighting/shader model you like.
• Use fog or other effects if you like. Different submissions are likely to vary considerably in size, so there's room to play a bit.

Criteria

• You must post code which can be run as-is, with the specified reference parameters and all your free parameters included.
• You can take the heightmap image as hardcoded in a representation of your choice and this does not count towards your golf score. You must post the code which converts an image to your preferred format. This script should either run using common Linux command-line tools, or over an online service. This script should not assume that heightmaps are square.
• The output of raw pixel data can be in any format you like (e.g. [[r,g,b],...] BUT you must provide a second script, not counted towards your golf score, which turns your program's raw output into some standard image format such as PNG. This script should either run using common Linux command-line tools, or over an online service.
• You must post the final image produced by this method, as well as the code which produces the output which produces the image.

In a nutshell, the above specifies that your output is reproducible, with different parameters and heightmap images as desired.

The winner will be chosen a few weeks from now, as the shortest code which conforms to the above aesthetic specifications (e.g. shadows, no holes, etc) and which gives end-to-end reproducible results.

Answer 17

First 100 prime numbers in Wentelx87 code-golf

Wentel consists of, at the basic level, a memory pointer and an instruction pointer. Instructions are stored loaded into memory. The execution pointer moves to the right after executing the instruction at that memory pointer.

The program is loaded into rightmost slot of memory. For example, if your program is 0010 0000 0101 0100, then the virtual machine will look like this when started:

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 0101 0100 (memory)
                                                            ^                   (execution pointer)
^                                                                               (memory pointer)

(from README)

---

Wentel documentation examples, thorough and clear explanation here.

Wentel is language that is very hard to program in. Unlike brain**k, functions and GOTOs can be implemented. It emulates real machine code/assembly much better than brainf**k.

Wentel is a simple language.

1. instructions are held in the rightmost cells, one cell = one instruction
2. execution pointer starts out on first instruction
3. execution pointer moves right
4. the same cells that hold memory hold instructions.
5. these are the opcodes:

0000 - no-op

0001 - if the current address's value is equal to the value stored by the adress defined by the next word, move the execution pointer to the address pointed to the next word after the word after the current address.

0010 - move memory pointer to address specified by next word.

0011 - deposit the current address of the execution pointer into the current memory address

0100 - increment current memory address

0101 - decrement current memory address

0110 - move memory pointer left

0111 - move memory pointer right

6. and here are the specialized opcodes for output.

1000 - output 0

1001 - output 1

---

That was a boiling down of Wentel. Please read the full docs. Now for the actual challenge. Output the first 100 prime numbers, separated by spaces, in Wentel.

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

Answer 18

A simple but fun code golf challenge!

Given positive integer n

create a 2 dimensional matrix where each location is filled with it's xy index (starting from the top left).

For example:

Your grid should look like: input: 2

00 10
01 11

input: 3

00 10 20
01 11 21
02 12 22

Once the grid is created, randomly fill each index. This can be with an 'x' or any other way to denote a spot has been filled

A complete simulation looks like:

input: 3

x x x
x x x
x x x

O O O
O O O
O O O

You can use whatever character you want to fill in each location.

Extra points if you use a GUI and use black squares to fill it in

You should only fill a spot in once so the number of times you fill should be n^2. (So no randomly filling spots until they are all filled you have to check!)

You can refresh the grid however you want. i.e print the grid, make a new line, print again... You can use a timer. However you want to do it to illustrate each step. You only need to refresh when you are filling not when you are populating the grid.

An example simulation looks like this:

input: 2

00 10
01 11

randomed 01

00 10
XX 11

randomed 11

00 10
XX XX

randomed 11
re-roll
randomed 01
re-roll
randomed 00

XX 10
XX XX

randomed 10

XX XX
XX XX

Complete

Do not display your randomed numbers, the output should tell me which were randomed.

Have fun!

Answer 19

Just like magic

code-golf kolmogorov-complexity

---

Nowadays, the word "abracadabra" is used mostly in connection with magic tricks. The original purpose of the word had more to do with superstition, and some doctors used it to make lethal diseases go away by writing it in a triangle¹, like so:

A B R A C A D A B R A
 A B R A C A D A B R
  A B R A C A D A B
   A B R A C A D A
    A B R A C A D
     A B R A C A
      A B R A C
       A B R A
        A B R
         A B
          A

Your task is to write a program or function that outputs/returns the exact text shown above in as few bytes as possible. The output may contain trailing spaces on each line and/or trailing newlines. This is code-golf, so the shortest code in bytes wins.

^{1. https://en.wikipedia.org/wiki/Abracadabra}

---

Sandbox questions

• Is it too simple?
• Is it a duplicate?
• Any better name ideas?

Answer 20

Ungolf batch

This question wants you to golf batch programms. In Batch you can use

set x=averylongbatchcommand
%x% arg1

which expands to

set x=averylongbatchcommand
averylongbatchcommand arg1

Your task is it to expand these statements.
As you can also use set for arithmetic purposes like this:

set x = 0
set /a x= %x%+1

you should ignore the statements where the pattern with set /a is applied.
There will never be something like

set s=SET
%s% s=%s% a

where the variable is assigned using itself as command. But you have to handle things like

b:
set a =echo
%a% Hello World!
set a=goto
%a% b

Scoring

This is code-golf so the answer with the fewest bytes wins.

Testcases

set s=set
%s% e=echo
%e% I will have to use this exact thing very often because
%e% it absolutely wouldn't be shorter if i just left out these set statements

Expands to:

set s=set
set e=echo
echo I will have to use this exact thing very often because
echo it absolutely wouldn't be shorter if i just left out these set statements

---

set s=set
%s% i=0
set g=goto
:a
if %i%==15 (
%g% e
)
%s% /a i=%i%+1
%g% a
:e

Expands to:

set s=set
set i=0
:a
if %i%==15(
set e
)
set /a i=%i%+1
goto a
e:

---

set s=set
%s% s=%s% a=

Mustn't be supported.

Answer 21

Convert Birkana to Hexademical

code-golf ascii-art string number hexadecimal

Introduction

Birkana is a not-very-well-known notation for hexadecimal using rune-like symbols. The general structure of a Birkana rune is like this:

|\     <-- 0x1
|/     <-- 0x2
|\     <-- 0x4
|/     <-- 0x8

The slash or backslash is present if its base number (0x1, 0x2, 0x4, or 0x8) is present in the number, or not otherwise. The pipe is always at the left-hand side.

For example, here's the Birkana rune for 0xD (= 0x1 + 0x4 + 0x8):

|\
|
|\
|/

Challenge

Given a Birkana rune as input, write a program or function to output the corresponding hexadecimal digit.

You may choose to output either lowercase (a-f) or uppercase (A-F) hex digits, but they cannot be mixed.

You only need to support the 16 hexadecimal digits and their corresponding Birkana runes.

Test cases

Input
Output

|
|
|
|
0

|\
|
|
|
1

|
|/
|
|
2

|\
|/
|
|
3

|
|
|\
|
4

|\
|
|\
|
5

|
|/
|\
|
6

|\
|/
|\
|
7

|
|
|
|/
8

|\
|
|
|/
9

|
|/
|
|/
A

|\
|/
|
|/
B

|
|
|\
|/
C

|\
|
|\
|/
D

|
|/
|\
|/
E

|\
|/
|\
|/
F

Scoring

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

Answer 22

Find the least squares regression line

code-golf math

Background

I'm taking AP stats now, so I figured I'd bring the joy to you all here.

The form of an LSRL (least squares regression line) is ŷ = a + bx.

Input

Your job is to find the least squares regression line for two data sets (lists), X and Y. X and Y will be the same size with at least 2 elements. They will contain positive or negative floats. Input can be taken in any reasonable format.

Output

The values a and b in the least squares regression line (LSRL) for the data in X and Y, where a is the y-intercept and b is the slope of the LSRL. This page describes a way to calculate this line.

This is code-golf, so shortest code in bytes wins!

Also, built-ins are allowed!

Examples

[1.0, 2.0, 3.0, 4.0] [12.0, 15.0, 16.0, 17.0] -> A: 11.0 B: 1.6
[1.5, 1.5, 51.0, -15.0] [2.0, 1109.0, 0.003, 2.0] -> A: 314.92 B: -3.7609
[1.0, 2.0] [1.0, 2.0] -> A: 0.0 B: 1.0
[-15.0, -13.0, -163.0, -12.25, -14.41, 100000.0, -630.0, -135.0] [-142531.0, -12.0, 153.0, -135.0, 135.0, 16.0, 21.0, 0.0] -> A: -20285.0 B: 0.20121
[3.0, 5.0, 7.0, 9.0, 11.0, 13.0] [2.0, 4.0, 6.0, 8.0, 10.0, 12.0] -> A: -1.0 B: 1.0

Answer 23

2D Poor Man's Plotting!

---

code-golfmath

---

Introduction

Surely you've also come across the problem where you have a multi-dimensional function at hand and want to visualize it (it's just such an everyday problem!). So we need a (programmatic) solution to this. A memorable solution, thus obviously the shortest solution is best!

Specification

Input

Your (primary) input will be a function that maps two floats onto another float.

Additionally there are six other parameters (floats), which you may take explicitely or hard-code:

• StartingValueX: 0
• StartingValueY: 0
• EndingValueX: 10
• EndingValueY: 10
• StepSizeX: 1
• StepSizeY: 1

You may take these parameters using your preferred method of input, but please document it (especially how the function should be passed).

Output

The output is a formatted string or a printed output (whatever pleases you).

What to do?

The introduction already hinted it:
Given a function that takes two floats as inputs, iterate it two-dimensionally and print the resulting values. So the top left entry is the result of the evaluation at (StartValueX,StartValueY) and the bottom right entry is the evaluation of (EndValueX,EndValueY) and then you form basically a table from this by incrementing the StartValue by the respective StepSize for each iteration.

Formatting guidelines:
Between each line may be one (or more) empty lines (eg end your lines with \n\n in C).
There must be at least one white space between every output number.
All numbers with the same x-coordinate must be aligned respectively to their start.

Potential Corner Cases

You may always assume a certain function prototype is used.
If EndValue-StartValue is not an exact multiple of StepSize (which may happen because we're dealing with floats here) then you shall compute for all StartValue + k * StepSize smaller than EndValue as well as for EndValue.
You may always assume the computation results (of the function) are actually representable in your language.
You may not assume that the function is a simple mathematical function (e.g. any valid function adhering to the above conditions in your language must work).
Trailing newlines and white spaces are allowed.

Who wins?

This is code-golf so the shortest answer in bytes wins!
Standard rules apply of course.

Test-cases

Default parameters, f(x,y)=x+y
Output:

0  1  2  3  4  5  6  7  8  9  10
1  2  3  4  5  6  7  8  9  10 11
2  3  4  5  6  7  8  9  10 11 12
3  4  5  6  7  8  9  10 11 12 13
4  5  6  7  8  9  10 11 12 13 14
5  6  7  8  9  10 11 12 13 14 15
6  7  8  9  10 11 12 13 14 15 16
7  8  9  10 11 12 13 14 15 16 17
8  9  10 11 12 13 14 15 16 17 18
9  10 11 12 13 14 15 16 17 18 19
10 11 12 13 14 15 16 17 18 19 20

Answer 24

[Lang1] vs [Lang2] ... vs [LangN]: Battle of the golfers!

code-golf teamwork and other tags for the challenge questions, which may be a lot.

Note: I haven't figured out all the kinks out yet, all I have is a general idea that, with your help, can be put properly into an awesome challenge (I hope). The parts where my ideas are not solid yet have Notes attached to them that must be read.

Team

In the midst of the nation of SE, there lies a golf field for the community of golfers. These golfers play day and night using specialised clubs (languages) to complete difficult and challenging holes (challenges). Now it is time to see the best of these golf clubs in the game!

Note 1: First of all, this challenge is going to be language-specific. I haven't decided the languages yet, but right now I'm thinking around the lines of Java, C, C++, C# since these languages are very well known, unlike the other esoteric languages.

You, the golfer, are to choose one golf club out from these [Lang1], [Lang2], ..., [LangN]. You will team up with other players using the same golf club as you.

Note 2: Now there is supposed to be a table where the players can edit into this challenge (once I post it) to join a team. After ~1 week from the beginning of the sign-up, people will start competing in the challenge.

This will be a sort of golf relay, where every player must only complete 1 hole, no more, no less. But of course, each player may help teammates to complete the holes using the minimum number of shots (bytes) as possible. All golfers, of every team, will be playing using the same playing field, in this case UTF-8.

The Challenge

There will be a list of challenges [see Note 3] to be completed by the team. Each team member must complete 1 challenge only. After a fixed amount of time (see Note 3), all team members must have complete their assigned challenges (see Note 4). I will sum of all the bytes used by each team to figure out the winning team (see Note 5)!

Note 3: Either I will provide all the challenges, or each team member may give 1 challenge to the challenge pool. Challenges can range from anything like quines and "Hello, World" challenges, to more complicated ones, like solving advanced mathematical (pardon me) mumbo jumbo and outputting complex sequences. Every team completes all of these challenges (see Note 4).
The time that I have decided, so far, is to give the entire team 3 weeks (subject to change) to complete their challenges.

Note 4: Each team member complete 1 challenge. However, if the team sizes are different, the team with the greatest number of members will have to complete all of the challenges. The other teams only have to complete as many challenges as members, so that there will be one for every member.

Note 5: The scoring will be the number of bytes used by each team, summed up, and then divided by the number of challenges completed.

Answering

Here is the format to each answer:

#Language, challenge-number, byte-count in UTF-8

for example:

#Java, #34, <s>463</s> <s>444</s>  <s>442</s> bytes

Summary

To sum it up, here is the process that this challenge goes through:

1. People who want to play must choose one team to be on, if they want to play.
2. After registration is over, the games begin: each player is to choose only one challenge and give a golfed answer. (Other players of the same team are allowed to help teammates)
3. After some time, when all the challenges are attempted (one for every person, if people haven't answered in this time, they won't be counted towards the challenge), I will calculate the score of each team (using the total bytes used).
4. Leaderboard is announced and the winning team walks away with all the glory!

Comment any ways this challenge can be improved. My general idea is to implement a team game, instead of the standard free-for-all.

Answer 25

King of the Hill: Moon Rockets

This is a challenge where you code bots to compete in an arena. In this case, you code a rocket flying over the Moon. Your goal is to shoot down enemy rockets, while not running out of fuel and crashing into the Moon.

Environment

Unlike many KOTH challenges the playing field is continuous, rather than discrete. You are provided with variables for your position, velocity, and the direction you are facing. Each turn, you are given a list of all the rockets you can "see" (all rockets less than 10 units away). You return a turning speed, thrust and whether you want to fire missiles.

Arena

The arena wraps left-right. There is a floor; if you crash into it going faster than 4 m/s, you will explode. There is no ceiling, but you do have a limit of 10 fuel units. This can be refueled by landing on the floor going less than 4 m/s.

Missiles

Every turn, you have the option to fire missiles. Missiles go in the direction you are pointing, at a constant velocity 5 m/s faster than you were when you fired. If they come within a 1m radius of another rocket, they explode and destroy it.

Gravity

Gravity is a constant force of 1 downward. With a max thrust of 2, you can accelerate at an equal rate in the opposite direction.

Pastebin for current controller code: http://pastebin.com/FNyjrJfr
No tournament code is in place yet.

Answer 26

C Compiler

Implement a basic C Compiler.

You do not need to implement the libraries. Compiler would output an object file containing a function, that would be linked with some libraries using GNU binutils ld and run.

No function calls, unions, structs, casts will be used in the test cases.

Test case:

int test(int i, int j) {
  int x[10][20];
  int s = i + j;
  i = 0;
  j = 0;
  for(i = 0; i < 10; i++)
    while (j < 20)
    {
      j += 1;
      x[i][j] = i * j;
    }
  for(i = 0; i < 10; i++)
    while (j < 20) {
      s += x[i][j];
    }
  return s;
}

---

code-golf

Answer 27

HamSort a list of strings

Given a list of strings, sort them in a manner such that the Hamming distance between each is minimal.

The Hamming distance between two strings of equal length is the number of positions where the corresponding characters do not match. For example, the Hamming distance between apple and ample is 1 since only the second characters of each do not match.

apple
ample
 *

Rules

• This is code-golf so the shortest code wins.
• Each string in the input list will have the same length and will consist of only the letters in the English alphabet. You may assume all to be either uppercase or lowercase.
• If there are multiple possible solutions, you may output any number of them.

Test Cases

<to be created>

Answer 28

How fast (slow) is your language?

This is a question both to test your coding skills but also to speed benchmark your favorite language. The code snippet will make a table of the fastest code per language. It is related to previous fastest-code [challenge]1 so you may find some of the code there a useful starting point.

The challenge is to write the fastest code possible for computing the permanent of a matrix whose entries are floating point in the range -1 to 1.

The permanent of an n-by-n matrix A = (ai,j) is defined as

Here S_n represents the set of all permutations of [1, n].

As an example (from the wiki):

In this question matrices are all square and will only have the floating point values in the range -1 to 1 (excluding both ends). I will construct all tests in such a way that the permanent is also in the range -1 to 1.

Examples

Input:

[[-0.34389946 -0.811193  ]
 [ 0.62778788 -0.09918764]]

Permanent:

-0.47514655471

Input:

[[-0.34389946 -0.811193  ]
[ 0.4783581  -0.56636227]]

Permanent:

-0.19326906099

The task

You should write code that, given an n by n matrix, outputs its permanent.

As the output will never be bigger than 1 in absolute value you do not have to worry about overflow. However you do have to worry about numerical accuracy. All answers should be correct up to 8 decimal places.

Languages and libraries

You can use any available language and libraries you like but no pre-existing function to compute the permanent.

More to be added..Work in progress

Answer 29

Directional Brainf*ck Compiler/Interpreter code-golf

Challenge: Write a Brainf*ck compiler with 4 extra commands.

L Set the direction to go left
R Set the direction to go right
D Set the direction to go down
U Set the direction to go up

The original commands (altered):

+ Increment the cell one
- Decrement the cell one
[ Start a loop, if the cell is 0 then go to the next ]
] end a loop if the current cell is 0. Else go back to the last [ read and continue from there (in the direction you were going last time it was read.
. output the byte at the data pointer.
, accept one byte of input, storing its value in the byte at the data pointer.
> point to the cell to the right
< point to the cell to the left

Compiler/Interpreter

In this case the compiler must either convert the code to another language or be an interpreter and run the code.

This is basically a directional version of brainf*ck. Directions should work the same way they do in ><>.

The pointer should start at the tape's beginning. It must be infinite in the right direction. Left infinite is optional (if you add it -10 to the score). Upon end of code output (in any reasonable form) the current values on all the stacks. If a ] is hit before a [ output a warning (with a message of your choosing). If a , is met at the end of the code you can do with it as you please. The program will terminate at the end of the file.

Standard loopholes apply.

Answer 30

Modular Reverse Recursion Sequence

Given any number n > 0, let r represent the reverse of the number n. Iterate until the final result is zero, passing the result of each iteration back into the function using recursion or a methodology of your choice by performing the below operation:

• If r > n for that iteration the result is r % n.
• If n > r for that iteration the result is n % r.
• If n % r = 0 or r % n = 0, you terminate iteration.

Take the intermediate result of each execution and store them in an array for the final answer.

Lets walk through an example where n=32452345.

54325423 % 32452345 = 21873078 # r > n, uses r % n
87037812 % 21873078 = 21418578 # r > n, uses r % n
87581412 % 21418578 = 1907100  # r > n, uses r % n
1907100 % 17091 = 9999         # n > r, uses n % r
9999 % 9999 = 0                # r % n = n % r = 0, terminated

Result: [21873078, 21418578, 1907100, 9999]     

Another example n=12345678:

87654321 % 12345678 = 1234575 # r > n, uses r % n
5754321 % 1234575 = 816021    # r > n, uses r % n
816021 % 120618 = 92313       # n > r, uses n % r
92313 % 31329 = 29655         # n > r, uses n % r
55692 % 29655 = 26037         # r > n, uses r % n
73062 % 26037 = 20988         # r > n, uses r % n
88902 % 20988 = 4950          # r > n, uses r % n
4950 % 594 = 198              # n > r, uses n % r
891 % 198 = 99                # r > n, uses r % n
99 % 99 = 0                   # r % n = n % r = 0, terminated

Result: [1234575, 816021, 92313, 29655, 26037, 20988, 4950, 198, 99]

A final example n=11000:

11000 % 11 = 0 # n % r = 0, terminated

Result: []