Sandbox for Proposed Challenges

Question

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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Answer 1

Pointfree Generator -- this is a draft.... --

What is this?

From Wikipedia's page:

Tacit programming, also called point-free style, is a programming paradigm 
in which function definitions do not identify the arguments
(or "points") on which they operate

Challenge

In this challenge, you will have to generate Haskell code in pointfree style. You can provide an answer in any language of your choice as long as it generates Haskell code.

The functions to generate will be polynomial function of multiple variables with integer coefficients like : f : x,y,z -> x^8*y*z + 3*y + 12

for example, the function f : x -> x² + 3x can be written in pointfree Haskell like this (3*)>>=flip((+).(^2)) or (+3)>>=(*)

Input

The input is a list of list of coefficients and exponants : For example, the f : x,y,z -> x^8*y*z + 3*y + 12 function will be defined as [[1,8,1,1],[3,0,1],[12]]

Output

Restrictions

Haskell function/operators allowed are the following : (+),(-),(*),(.),(^),flip,(=<<),(>>=)

Hints

Testing

Scoring

Answer 2

Pitchers and Rivers

Credit for the idea for this challenge goes to Dan Garcia of UC Berkeley.

Many of you may have heard of any number of variations on the pitcher problem. For those who haven't, or need a refresher, the generalized form of the pitcher problem is as follows:

Given a list of pitchers of known size and a river filled with infinite water, how can you obtain a specific amount of water?

For a more specific example:

Given a 3-liter pitcher, a 7-liter pitcher, and a river, you can obtain exactly 2 liters as follows:

1. Fill the 3-liter pitcher.

2. Pour the 3-liter pitcher into the 7-liter pitcher.

3. Repeat steps 1 and 2 again twice.

4. If you didn't spill any extra water when filling the 7-liter pitcher the third time, the 3-liter pitcher will now contain 2 liters.

You cannot pour out part of the pitcher unless you can measure how much you poured out by filling something else up, e.g. another pitcher.

Your goal, now, is to determining which amounts of water you can get from your pitchers, given their sizes... but generalized to any number of pitchers.

Input

You will receive the pitcher sizes in any reasonable format. A (non-exhaustive) list of examples are:

1. A newline-separated list. 5\n13\n532

2. A Pythonic list. [3,7,13,22]

3. Prompt for input, like BF's .[>.]

You do not have to handle invalid input (e.g. negative sizes, empty lists)

Output

A list of obtainable (measurable) amounts of water, in any reasonable format. You may include 0, but you do not need to. You do not need to list the steps by which you obtain these quantities.

[3,5] -> [1,2,3,4,5,6,7,8]

[3,3] -> [3,6]

[4,6] -> [2,4,6,8,10]

[7, 5, 3, 2] -> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]

[30, 15, 5] -> [0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50]

[5,0] -> [0, 5]

[-1] -> Undefined behavior; sizes are always positive 

Reference solution in Pyth, barely golfed (100 bytes)

Answer 3

Code Golf: Convert to base 6 and back

If given a number, convert it to base 6. You can assume it is positive. You can get the number through any of these methods: STDIN, or ask for user input. If i has a 'o' at the end of it then assume the number is base 6 and convert it to a decimal number. Assume i is a string.

Example: Given i convert it. So if i = 12 then return 20. Given i convert it. so if i = 12o then return 8

Answer 4

Quine and Antiquine

code-golf quine

Your task is to make two different program, A and B. Both are nonempty proper quine. However, there is a restriction.

1. AB and BA produce no output.
2. CABD and CBAD will do the same thing as CD, where C and D are any (potentially empty) strings made up of copies of A and B. E.g. ABBABA and ABBBAA should behave identically (here, C = ABB and D = A).

The score is the sum of the length of A and B.

Example:

A program written in DJam:

program A :

abcd

program B :

efgh

Then, these output are sastified

abcdefgh
>> <empty output>
abcdabcdefgh
>> abcd
abcdabcdefghabcdefgh
>> abcd

Answer 5

Periodic Pillbox Problem code-golf

Pill-popping Patty is prescribed to take a particular pharmaceutical every P days. Presently, Phil has punked Patty's pill-box, punching holes in particular weekday's plastic pockets. Patty proceeds to plan pills P days apart whenever possible, but places pills in the preceding day's plastic pocket if the preferred pocket is punctured. Produce a pill planning chart presuming Patty popped her prior pill on the penultimate day of the previous week.

In case it's not clear, this is the kind of pill-box I am referring to.

---

Input:
The number P, followed by the 1 to 6 weekdays that Phil punctured. Beginning with Sunday(N) the weekdays are N M T W R F S. For instance 5MRF means Patty aims to wait 5 days after each pill, but cannot plan pills on Monday, Thursday, or Friday.

You can have the input with a single space after the number (e.g. 5 MRF) or with spaces after the number and each day (e.g. 5 M R F).

Process:
Given 5MRF Patty's first pill is taken on the first Wednesday (5 days from last Friday). Her second pill should be taken on the second Monday(5 days from the first Wednesday), but is moved up to the second Sunday because Monday is punctured. Her third pill should be taken on the second Friday(5 days from Sunday, not Monday), but is moved up to the second Wednesday because Friday and Thursday are both punctured. She continues in this manner indefinitely.

Note on the first week Patty's pillbox contains one pill on Wednesday, on the second and future weeks it contains pills on Sunday and Wednesday.

Output:
The pill planning chart shall indicate the state of Patty's pill-box each week, one week per line. Days she does not take her pill must have a dot ·. Days she takes her pill must have a capital X. The chart must stop as soon as the cycle occurs (i.e. in the fewest lines possible) with an arrow > pointing the first week in the cycle on the left. All weekdays must align in singly spaced columns with Sunday on the left.

Notes:
You may assume Phil was not malicious enough to puncture P consecutive days of the weeks, and that P is between 2 and 7 inclusive.

If Patty can't take her pill on the first Sunday, she takes it on the previous Saturday. Her pillbox was not damaged last week.

A cycle has occurred when pills are being taken on the same weekdays as in an earlier week.

Patty never waits more than P days to take her pill.

---

Testcase 1: 5MRF

  · · · X · · ·
> X · · X · · ·

Testcase 2: 5MR

> · · · X · · ·
  X · · · · X ·

Testcase 3: 5MF

  · · · X · · ·
> X · · · X · ·
  · · X · · · ·

Testcase 4: 6NTFS

  · · · · X · ·
> · · · X · · ·
  · X · · X · ·

---

A reference solution in C++ is provided here.

---

For The Sandbox...
First Challenge. Hooray! My biggest concern is whether or not there is anything with a similar process, I'm not sure if there is a generalization or a name for this sort of elimination thing. Barring that, is a good golfing question, can it be made a better golfing question, is clear what has to be done, etc. Really any advice is welcome.

Answer 6

Checkmate (aka the urinal problem) V2

inspired by Checkmate (aka the urinal problem)

given a non-negative integer n, assume there are n urinals.

also assume that you are not allowed to use an urinal when

• it is out of order.
• or a neighboring urinal is occupied.

If no urinal is available, the situation is considered checkmate.

Challenge:

Create a program or function that finds and prints (or returns, or yields) all possible checkmate combinations for n urinals.

Input: STDIN, command line argument or function argument

Output: Any output that makes the combinations clear is accepted.

---

TODO: add visual and test cases.

a thought:
This cries for string operations; how about a bonus for a calculational solution? Do bonuses suck?

Answer 7

Compute The anti-derivative of a non-constant function

Most of us know how anti derivatives work. They are basically the sums of infinite number of very small elements (or units).

The challenge here is to calculate anti derivative of a function (NON CONSTANT). using any programming language except the ones which calculate anti derivatives directly (Mathematica for instance).

Anti derivatives which have been calculated must be done by the usual summation method which is basically the definition of the integral. Summation of y.dx over some interval of x)

You basically have to find the anti derivative WITH limits i.e. definite integral of a non constant function in between two user specified limits

Answer 8

Download a file code-golf

Your boss wants you to make a comprehensive download utility. She uses Microsoft Bob and thinks shorter code is better code.

The Gist: In as few bytes as possible, given an input URL, output the file to stdout.

Input

• You will be given a fully qualified (w/ http/https) URL.
• Download link may redirect. Follow all redirects.
• Any non 2xx-3xx status code should be interpreted as an error. Exit with a status code of zero.
• Verify SSL certificates - exit with 0 if invalid

Misc

• Do not use a preexisting utility already designed for downloading files, such as wget. This is considered cheating.

Answer 9

Handwriting Recognition

code-golf image-processing

The MNIST dataset is a series of handwritten digits used as a standard testbed for machine learning, pattern recognition techniques. Each image is of a single digit, 0-9; as a 28x28 pixel grayscale matrix with values from 0-255.

The challenge is to create a classifier for MNIST that scores an Error Rate of less than [TBD] in the least number of bytes possible.

Your program must take a 28x28 2d array in whatever format is applicable for your language representing a single image. For example, the input for the first digit might be:

[[  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3, 18, 18, 18,126,136,175, 26,166,255,247,127,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0, 30, 36, 94,154,170,253,253,253,253,253,225,172,253,242,195, 64,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0, 49,238,253,253,253,253,253,253,253,253,251, 93, 82, 82, 56, 39,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0, 18,219,253,253,253,253,253,198,182,247,241,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0, 80,156,107,253,253,205, 11,  0, 43,154,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0, 14,  1,154,253, 90,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,139,253,190,  2,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 11,190,253, 70,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 35,241,225,160,108,  1,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 81,240,253,253,119, 25,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 45,186,253,253,150, 27,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 16, 93,252,253,187,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,249,253,249, 64,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 46,130,183,253,253,207,  2,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 39,148,229,253,253,253,250,182,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 24,114,221,253,253,253,253,201, 78,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0, 23, 66,213,253,253,253,253,198, 81,  2,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0, 18,171,219,253,253,253,253,195, 80,  9,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0, 55,172,226,253,253,253,253,244,133, 11,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,136,253,253,253,212,135,132, 16,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
 [  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0]]

Conditions:

• This is code golf. The shortest piece of code that meets the criteria wins.
• The code must take a provided 28x28 input and attempt to classify it.
• Testing will take place on my computer at 12pm AEST on Saturday the . I will run each classifier over a set of 1000 images. To be considered, it must correctly classify [TBD] of them. If I can't get your code to run, it wont be counted, so help with loading the images in your language would be appreciated.
• Standard loopholes are not permitted.

Questions for Sandbox

• Overall thoughts on the challenge?
• Has anything been done like this before? Did it work?
• Any ideas on a good cutoff for the classifier? I was thinking around 60% correct. Though was going to have a go at it myself to see what I could reasonably achieve.
• Does the testing clause make sense? Is it reasonable? Should I put a limit on the languages?
• Since barrier to entry is a bit high (knowing how to get hold of the images, possibly some ML experience), is there anything extra I should do to make it easier to start the challenge.
• This is my first suggestion for a challenge, is there anything I'm missing?

Answer 10

Gif - Jif, Jif - Gif

code-golf

_{The point of this challenge is to (not) settle debate on the pronunciation of "gif"} http://38.media.tumblr.com/11bc6092d29c8c6840f9e10184ca03fd/tumblr_mlksz8SLjn1qz4h3co1_1280.gif

---

The pronunciation of gif is debated and while it's supposed to be (and should be) pronounced jif, it's still commonly disputed.

In this challenge you will be given a set of words that have a g or j, representing the sound that the word is pronounced with. You'll also get some text in which you have to fix the incorrect spellings of gif.

Because this is the internet and everyone always wrong. It's (not) common courtesy to correct them.

An example of a wrong pronunciation would be:

There was a gif of a mouse eating a burrito

The wrong spelling of gif? Unacceptable! This must be corrected immediately:

There was a jif (as in jar) of a mouse eating a burrito

---

Are we done? Nope, you're still wrong.

You're always wrong http://travelsummary.com/wp-content/uploads/2013/03/Im-Right-Youre-Wrong-e1363993322818.jpg

This must work the other way:

In the jif the cat wore a hat of a cat

This obvious misspelling must be fixed, we shall correct this to:

In the gif (as in graphic) the cat wore a hat of a cat

---

Rules

• You may assume all words that contain the letter g have the hard g sound (as in gravy) and all words that contain the letter j have the j sound (as in jam)
• Words will never have both g and j (Will add more specific rules later)
• Words must be picked at random each item with the same chance of being picked
• Words may be supplied through an array or the closest alternative for your language.
• Case must be preserved E.g. GiF -> JiF.
• You may write a program or a function

---

Examples

Input and output separated by a single line:

graphic, jar, jam, gram
I saw a jif of how to pronounce gif that showed gif is pronounced jif

I saw a gif (as in graphic) of how to pronounce jif (as in jar) that showed jif (as in jam) is pronounced gif (as in gram)

gravy, jeff
G is for gif, h is for jif, i is for gif, j if for jif

G is for jif (as in jeff), h is for gif (as in gravy), i is for jif (as in jeff), j is for gif (as in gravy)

Answer 11

Largest Number Given Digits and Operators

---

Challenge

Given a list of digits (0-9) and operators (+, -, /, *), output the largest number that can be formed using those digits and operators, as well as the mathematical formula used to create this number.

Rules

• All digits and operators must be used once and only once
• Parenthesis may be used in the outputted mathematical formula
• The outputted mathematical formula must be valid in an interactive Python shell (Note, this means ["--", "---", etc.], "//", "**", and ["++", "+++", etc.] are all valid operations that can be used in the output)
• Base 10 will be used
• For multiple different formulas that result in the same maximum number, output whichever one
• Input may contain any number of digits and operators
• Answers can be a function or program, and will be scored in bytes
• No loopholes or built-ins

Example I/O

Input: [1, 4, 3, *, +]
Output: +31*4
        124

Input: [1, 2, 0, '+']
Output: +210
        210

Answer 12

The one-looper ASCII box

Intro

I saw this one in one of my university programming textbooks as an "advanced" exercise and I thought it would fit very well here.

Task

Your program have to ask for an input number and draw a box with the size of the given number and a cross in it.
Example if the number is 7:

+-------+
|\     /|
| \   / |
|  \ /  |
|   X   |
|  / \  |
| /   \ |
|/     \|
+-------+

Example if the number is 10:

+----------+
|\        /|
| \      / |
|  \    /  |
|   \  /   |
|    \/    |
|    /\    |
|   /  \   |
|  /    \  |
| /      \ |
|/        \|
+----------+

The minimum width is 1 and it looks like this:

+-+
|X|
+-+

Notice that with an odd size, there is an X in the middle.

The hard part

In your program only one function is allowed (main) and in the main function there can be only one loop and that loop can only have one statement which can't be if. The shortest answer wins!

note: Sorry for the messy description but I had to translate it from my native language.

Answer 13

Interpret loose ranges code-golf

ListSharp is an interpreted programming language that has many features, one of those features is a 1 index based range creator that works like this:

You define a range as (INT) TO (INT) or just (INT) where both or the single int can go from min to max int32 value

Then you can use those ranges to extract elements of an array without fearing to overstep it's boundaries

---

therefore:

1 TO 5 generates: {1,2,3,4,5}

3 generates: {3}

Ranges can be added up using the AND operator

1 TO 5 AND 3 TO 6 generates: {1,2,3,4,5,3,4,5,6}

remember this works with negative numbers as well

3 TO -3 generates: {3,2,1,0,-1,-2,-3}

---

The challenge is the following:

Input

A character array and the previously defined range clause as a string

Output

The elements at the 1 index based locations of the range (non existing/negative indexes translate to an empty character)

---

How to win

Create the program with the shortest byte count

---

Test cases:

input array is:
{'H','e','l','l','o',' ','W','o','r','l','d'}

range clause:
"1 TO 3" => {'H','e','l'}
"5" => {'o'}
"-10 TO 10" => {'','','','','','','','','','','','H','e','l','l','o',' ','W','o','r','l'}
"0 AND 2 AND 4" => {'','e','l'}
"8 TO 3" => {'o','W','','o','l','l'}
"-300 AND 300" => {'',''}

Answer 14

Balanced Columns

I have a number of paragraphs of various heights which I would like to be distributed between some columns as evenly as possible. Here evenly means that you should minimise the total height of the tallest column, and then maximise the height of the shortest column, excluding empty columns.

The input will be an integer, representing the number of columns to be output, and an array of integers, representing the paragraph heights in lines. There is more than one way to represent the output; it could be an array (one for each column) of arrays of paragraphs, or it could be an array (one for each paragraph) of columns. (Please indicate whether your arrays are 0- or 1-based.) You may use any convenient format for (e.g. the number of columns as a command-line parameter and the array on STDIN) for I/O.

Because the paragraphs are double-spaced, there will be at least two lines in each paragraph, but if you prefer, your answer can take the double-spacing into account internally.

Within each column, paragraphs should be listed in ascending order, and the columns should be listed in ascending order of their first paragraph. Examples:

2, [2, 3, 4, 5, 6] -> [2, 3, 5], [4, 6] or [0, 0, 1, 0, 1]
3, [2, 3, 4, 5, 6] -> [2, 5], [3, 4], [6] or [0, 1, 1, 0, 2]
4, [2, 3, 4, 5, 6] -> [2, 3], [4], [5], [6] or [0, 0, 1, 2, 3]
5, [2, 3, 4, 5, 6] -> [2, 3], [4], [5], [6] or [0, 0, 1, 2, 3]

Note that in the last example the height could not be reduced by adding the extra column so in this case only four columns could be utilised.

Answer 15

No, this challenge is not this

Where is my error?

My compiler has broken down and now it is only showing the index of the character which the error is on.

In this challenge you will write a program to point to the given character.

Examples

Input:

if (goat == Downgoat) {
    print(Downgoat));
}

43

Output:

1 | if (goat == Downgoat) {
2 |     print(Downgoat));
  |                    ^
3 | }

Spec

TODO

Answer 16

Is this Rubik's Cube Solvable?

The challenge: find out if a rubik's cube configuration is solvable.

Takes input as a multidimensional array. An example for a solved cube would be

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

starting on the sides, going round, then top, then bottom. This input would give an output of 1, since it is solvable (very, very solvable). A (small) net of this solved cube would therefore be:

     _
 _ _|4|_
|0|1|2|3|
 ¯ ¯|5|¯
     ¯

The result of the program should be a truthy/falsey value, printed to STDOUT or similar. This is code-golf, so shortest answer in BYTES wins. Standard loopholes apply.

code-golf

Answer 17

Image Smoothing

Input into your program a black and white image. (png, jpg, etc)

Convert the image to a 2-d matrix of pixels. Where each index is the grayscale value of the image.

Take each index of the matrix and average the 8 pixels around it. Then replace that index with the average.

For example if you had:

120 80  60
20  10  30
40  100 05

If you were finding the average for 10, the result would be 56.875. Round to up to the nearest integer (57) and replace the index. The result of this iteration would be

120 80  60
20  57  30
40  100 05

If you are finding the average for a pixel on an edge then only take values that are valid. In the example above if you were finding the average for '20' You would only consider 112, 80, 57, 100, and 40, which is 79.4 rounded to 80.

You may start at any index of the graph but it must be in order, for example of you must go right - left, left - right, up - down, or down - up. You may not go something like randomly pick the indices to average.

Once the averaging is complete, convert the matrix back into a new image.

display the new image as the output of the program. (Or save it and add it in your solution). The result of this process should be a normal crisp looking image and the result would be a smoothed out image.

Please provide your code and start and end image (SFW please) and remember this is code-golf so the shortest code wins!

Good Luck and have fun!

Answer 18

code-golf internet

Implement BozoCrack

Designed to show why MD5 is a bad solution to password hashing, BozoCrack, for the uninitiated, is a rather simple and efficient method of cracking MD5 hashes. It doesn't brute force, use rainbow tables or indeed, any sort of math at all.

Instead, it finds the key by searching google for the hash and comparing the hash of each word in the results with the input.

Your task is simple: given at least one valid MD5 hash in a reasonable input format, find their source texts using Google and return or print to stdout the results.

In fact, you could probably arrive at the answer by finding the word in the page with the most occurrences -- you needn't use the results for a dictionary attack, but you must use Google.

The inputs can be given as an array of strings, as program arguments, space or otherwise delimited strings on standard input or in a file, etc -- whatever's easier for you, but make sure you specify in your answer how the input is taken.

Example inputs / outputs:

Input                            : Output
fcf1eed8596699624167416a1e7e122e : octopus
bed128365216c019988915ed3add75fb : passw0rd
d0763edaa9d9bd2a9516280e9044d885 : monkey
dfd8c10c1b9b58c8bf102225ae3be9eb : 12081977
ede6b50e7b5826fe48fc1f0fe772c48f : 1q2w3e4r5t6y

Of course, you may use your language's library function for computing the md5sum of a string -- but please, don't use any functions or libraries designed to solve exactly this task, e.g. Python's PyBozoCrack and the original BozoCrack.rb are disallowed.

In the unlikely event there are no results for a sum, print "NO RESULTS" to stdout instead.

Answer 19

AlphaGo..olf?

code-golf

(Slight paraphrased) Extract from Wikipedia:

AlphaGo is a computer program developed by Google DeepMind in London to play the board game Go and is the first computer Go program has beaten a 9-dan professional without handicaps.

In order to appreciate the Go art more, let's try to simulate what happens to the game when a move is made!

Input

The input will be:

1. a 4x4 board, (Here . denotes empty, o and x denotes different color of stones held by the 2 players respectively for illustration. Any standard input formats (2d array, array as sequence of alternative moves...) are welcomed as we like nice algorithms!)

2. a move to be made (Like A4, B2. You may also like to use 0-indexed and both numeric indices like (0,0)..(3,3)) For simplicity's sake, the move to be made is always with o (i.e. always the same color).

Output

The board after the move is made. Stones of the opposite color (i.e. x) will be taken away iff there are no more connected x that has at least 1 . in its 4-neighbor (Up, Down, Left, Right).

Examples

  Input | Move | Output
  ABCD  |      |
1 ....  | A1   | o...   (case 1: all stones remains on board)
2 ....  |      | ....
3 ..x.  |      | ..x.
4 ....  |      | ....
--------+------+--------
  ....  | B1   | .o..
  oxo.  |      | o.o.   (case 2: x taken away: the only . is taken)
  .ox.  |      | .ox.
  ....  |      | ....
--------+------+--------
  ..o.  | B1   | .oo.
  oxxo  |      | o..o   (case 3: >1 x taken away: the only . is taken)
  .oxo  |      | .o.o
  .xo.  |      | .xo.
--------+------+--------
  o.xo  | B1   | oo.o
  ..o.  |      | ..o.   (case 4: Edge case)
  ....  |      | ....
  ..o.  |      | ..o.
--------+------+--------
  x.o.  | B1   | .oo.
  ooxo  |      | ooxo   (case 5: Corner case)
  ...o  |      | ...o
  ..o.  |      | ..o.
--------+------+--------
  xxxx  | B2   | ....
  x.xx  |      | .o..   (case 6: Enclosed by Board case)
  xxxx  |      | ....
  xxxx  |      | ....
--------+------+--------
  .oxx  | C2   | .o..
  ox.x  |      | o.o.   (case 7: Enclosed by o case)
  oxxx  |      | o...
  .ooo  |      | .ooo
--------+------+--------
  .xo.  | A1   | o.o.
  xo..  |      | .o..   (case 8: taking multiple groups case)
  o...  |      | o...
  ....  |      | ....
--------+------+--------

Rules

1. This is code-golf thus the shortest code wins.
2. Please kindly provide explanations and ways to test the solutions!
3. The Input board can be assumed to be correct: there will be neither x that without a connected x with ., nor a group of o surrounded by x without .
4. The Input move can be assumed to be legitimate: either it won't be a position surrounded by x, or it must take away some x to free . for the o to live. (ref. case 6, 7, 8)
5. The output must be the board, it may or may not be in the same format as the input (if you take input as 2 arrays of o and x positions, say). Output that only shows the stones that are taken away after the move is made will not be accepted.
6. Again, feel free to play with the standard input formats. Hope to see interesting 1 and 0 playing Go instead of o and x :P

Meta Questions

1. I don't know if this may be too hard. Would it be better if I allow golfers to fail some test cases and get penalty instead?
2. Should I stick with a 4x4 board or I can award minus scores if the solution can work with a 19x19 board?
3. If it is a yes to any of the above questions, which should be the number for the penalty / award?

Thanks!

Answer 20

Categorize the asymptotic behavior of a consumer/producer system

Given two functions P(t) and C(t), output the correct category for the behavior of P(t)-C(t) as t goes to positive infinity:

1. Ideal: P(t)-C(t) goes to 0.
2. Stable: P(t)-C(t) oscillates, with the time spent as a positive value equal to the time spent as a negative value within a single oscillation period.
3. Hungry: P(t)-C(t) either converges to a negative value, or oscillates, with more negative values than positive values in one oscillation period.
4. Starved: P(t)-C(t) diverges, approaching negative infinity.
5. Saturated: P(t)-C(t) either converges to a positive value, or oscillates, with more positive values than negative values in one oscillation period.
6. Oversaturated: P(t)-C(t) diverges, approaching positive infinity.

Rules

• The expected output will always be one of the above cases - you don't have to worry about other cases
• P(t) and C(t) will always be real-valued continuous functions that only consist of the following operations: addition, subtraction, multiplication, division, exponentiation (for constants a and b and parameter t, a^b, t^a, and a^t are all allowed), principal roots (real roots, only when they exist, and only the positive root when there are 2 real roots), logarithms, and basic trigonometric functions (sine and cosine of arbitrary values, and tangent for values that are not odd multiples of pi/2)
• Input may be in any reasonably format (string, function object/pointer, mathematical function object, etc.)
• You may use any unambiguous set of 6 values for output (like [1, 2, 3, 4, 5, 6], [0, 1, 2, 3, 4, 5], [Ideal, Stable, Hungry, Starved, Saturated, Oversaturated], or [0, ~, -, -∞, +, +∞])

Test Cases

TBD

Sandbox Notes

• Are the definitions and rules clear?
• Are there any I/O methods that should be explicitly allowed or forbidden that aren't covered by the current rules?

Answer 21

(Need a title.)

Your task is to write 3 programs (or functions) that check if the input is a string of balanced brackets satisfying all the following criteria:

• The number of []s is always less than or equal to the number of ()s surrounding each position.
• The number of {}s is always less than or equal to the sum of the numbers of ()s and []s surrounding each position.
• The number of <>s is always less than or equal to the product of the number of () [] and {}s surrounding each position.

You can assume that:

• There are only the characters ()[] in the input of your program 1.
• There are only the characters ()[]{} in the input of your program 2.
• There are only the characters ()[]{}<> in the input of your program 3.

Your score is the product of (the length of each program + 1). Lowest score wins.

Examples

(To do.)

Answer 22

Quine tree

Inspired by that really weird quine challenge

For this challenge, you must construct a quine tree, which is a thing I made up, specifically an infinite binary tree.

How a quine tree works:

A quine tree has infinite nodes.

• Each node is associated with a program

  • Let X, Y, Z, be the programming languages. This program is a polyglot in X and Y. In all but the root node, it is also a polyglot in Z. Note the

  • see below for more details

• Each node has exactly two children

• Every node but the root has a parent. Their parent has the node as a child (obviously).

Programs:

• When a node's program is run in X, it produces the program of the first child of that node.
• When run in Y, it produces the program of the second child of that node.
• The programs produced must be different (node foo's program, cannot have the same output in X and Y. This output must also be different than the nodes program).
• If not the root node, when run in Z, it produces the parent of the node.

Example

Imagine that we have the (fake) programming languages Hello, World, and Foobaz. Say the root node is $QQ$QQ$;:

• when run in Hello, perhaps it produces $QQ$QQ$;;
  • When this is run with Hello again, perhaps produces $QQ$QQ$;;;
  • When this is run with World, perhaps produces $QQ$QQ$;;Q
  • Both these programs must produce, run in Foobaz, $QQ$QQ$;; (Output of root node run in Hello)
• when run in World, perhaps it produces $QQ$QQ$;Q
  • When this is run with Hello, perhaps produces $QQ$QQ$;Q;
  • When this is run with World again, perhaps produces $QQ$QQ$;QQ
  • Both these programs must produce, run in Foobaz, $QQ$QQ$;Q (Output of root node run in World)
• Both these programs, run in Foobaz, must produce $QQ$QQ$; (root program).

Answer 23

Fastest Cashier in the West

You're trying to design an automatic cashier that is able to dispense the correct amount of change in any denominations as quickly as possible. Your goal is to implement a program that accepts a target integer T ≥ 0 which is the amount you're trying to make change for, and a set of positive integers {c₁, c₂, ..., c_n} which are the values of each coin where you have an infinite number of each, and output all possible solutions for making change with those types of coins.

For example, if you're trying to make change for 123 and the coins available are {12, 16, 20, 27}, then there are 8 possible solutions

12 16 20 27  (123)
 0  1  4  1  means zero 12's, one 16, four 20's, one 27
             also 0*12 + 1*16 + 4*20 + 1*27 = 123
 0  6  0  1
 1  4  1  1
 2  2  2  1
 3  0  3  1
 4  3  0  1
 5  1  1  1
 8  0  0  1

Format

The input will be formatted as

T
N
c1
c2
...
cN

where T is the target value, N is the number of coins, and each cK is the value of coin k. Also, the coins will be listed in ascending order.

For example,

123
4
12
16
20
27

The output will be format as

x11 x12 ... x1N
x21 x22 ... x2N
...
xM1 xM2 ... xMN

where M is the number of solutions and N is the number of coins. Each line will contain the number of each coin needed to reach the target value separated by spaces. You may have trailing whitespace on each line.

For example, the output to the input above would be

0 1 4 1
0 6 0 1
1 4 1 1
2 2 2 1
3 0 3 1
4 3 0 1
5 1 1 1
8 0 0 1

You may output the solutions on each line in any order, but each solution must be unique.

Rules

• This is fastest-code so your only goal is to make your program as fast as possible.
• Builtins or libraries that solve this problem directly are not allowed.
• In the interests of having fine submissions, the deadline will be by December 12, 2016, which is almost two months.
• Your program must be single-threaded. However, you are allowed to use SIMD instructions and any other features of the CPU.
• The code will be ran on my machine which uses Fedora 24 x64 and has an i7-920 with 18 GB of memory.
• Please provide compilation instructions and version information if your program requires it.
• Please do not obfuscate your code unnecessarily. If I am suspicious of certain code and/or libraries, I reserve the right to ignore your submission.
• This is optional but if you are using advanced mathematical strategies, commenting and explaining your program would be very much appreciated.

Thoughts

The test cases will be created and provided as a download if there is interest.

For scoring, there will be a hidden dataset that is ran when the deadline is reached for final scoring purposes. After this is complete, the hidden dataset will be released along with the winner.

For extra incentive, should I increase the best answer reward by including a bounty. Or maybe for the three fastest?

Is it okay to ban commercial products as I may not have access to some of them. It wouldn't be fair to allow Mathematica and not Matlab/Maple/etc.

@PeterTaylor: I have an implementation in Python that uses a memoized recursive function and I would say its performance is decent at best. I do agree that I/O could be a bottleneck but I could choose test cases that have few or no solutions. Using methods to calculate the Frobenius number would help find those, but I would still like to see a few cases with a large number of solutions. I see two options. First, I could require the output to be ordered so that results could be piped into another program and avoid hitting the disk while being verified. The second is to test each program twice, first with the output enabled to check the accuracy, and if accurate, the second run would be with the output disabled to measure the execution time.

Answer 24

It's time to parse (everything)!

code-golf parsing

---

Introduction

The real world is hard. Internet standards suck. However they're used everywhere anyways. One standard in particular has been the source of a lot of trouble and frustration.
ASN.1
Abstract Syntax Notation 1
is used in many many places (including when parsing website certificates) and now it's up to you to implement a simple ASN.1 parser in your favourite programming language!

Specification

Input

Your input will be an ASN.1 encoded object. The encoding that is used will be PEM (thus it's all ASCII). You may take this input as a file, as STDIN, as a function argument as a string, as a byte sequence, whatever you like. The way your program takes the input should be documented however.

If you take file input, you may have the file name as an additional argument.
If you produce file output, you may have the file name as an additional argument.

Output

The output will be formatted ASCII text, this may be STDOUT, a returned string, a file, whatever, but document it.

What to do

You need to parse an ASN.1 object and return a nice textual representation of the content structure.
This means that there should be some sort of intendention whenever a nested structure is opened (by putting spaces or other signs in front of the identifier).
It also means that you should print the keyword whenever one is hit (also see the example).
You may but do not have to also output actual (decoded) contents or looked-up identifiers.

Warning

While I've always talked about an ASN.1 object, I actually had X.509 certificates in mind. So the parser should understand everything that occurs inside an

List of mandatory keywords:

SEQUENCE
OBJECT
UTCTIME
PRINTABLESTRING
SET
UTCTIME
NULL
OCTET STRING
BOOLEAN
UTF8STRING
BIT STRING
OBJECT IDENTIFIER
IA5STRING

Who wins?

This is code-golf, so the shortest answer in bytes wins!
Standard rules apply of course, built-ins are allowed.

Example Input and Output

Input: The Amazon.com X.509 certificate:

-----BEGIN CERTIFICATE-----
MIIFejCCBGKgAwIBAgIQfkmWRZCbTGK0b6jFJo0YnjANBgkqhkiG9w0BAQsFADB+
MQswCQYDVQQGEwJVUzEdMBsGA1UEChMUU3ltYW50ZWMgQ29ycG9yYXRpb24xHzAd
BgNVBAsTFlN5bWFudGVjIFRydXN0IE5ldHdvcmsxLzAtBgNVBAMTJlN5bWFudGVj
IENsYXNzIDMgU2VjdXJlIFNlcnZlciBDQSAtIEc0MB4XDTE2MDUxODAwMDAwMFoX
DTE2MTIzMDIzNTk1OVowaDELMAkGA1UEBhMCVVMxEzARBgNVBAgMCldhc2hpbmd0
b24xEDAOBgNVBAcMB1NlYXR0bGUxGTAXBgNVBAoMEEFtYXpvbi5jb20sIEluYy4x
FzAVBgNVBAMMDnd3dy5hbWF6b24uY29tMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A
MIIBCgKCAQEAuwQMfKRRZpql3WBS0uo4DfMrrkAEX9+6UD2fVSmV21i9iqCecmHa
4z9LNzeKqpGNkpTbXMaJfLxy0ehoQp7vyVIit6l+VZ9L+VTiL0+v8MjG+Kl6Sg4J
6ozV+EHck91Id8zCUyLHLcmJ5f60kazJJC1zGKlTkZR6Of0SzcLrje0T3Pqmdybj
AjFoBMdk0G1rKctxds1UnywI4pIONzsmozzPjk8Up5NA1s3bo9ubCQUcPSEm1TDJ
4TDdQVL8WsDNjY0SwTiVmJ+vo4TVIhRlfGv+xzHe8JXFYxsVJZ/FP70uFRH5+Uku
4yaGYFZYt71V3kOTzM3FvRlHb93jANoAHwIDAQABo4ICCDCCAgQwgb0GA1UdEQSB
tTCBsoIKYW1hem9uLmNvbYIIYW16bi5jb22CEXVlZGF0YS5hbWF6b24uY29tgg11
cy5hbWF6b24uY29tgg53d3cuYW1hem9uLmNvbYIMd3d3LmFtem4uY29tghRjb3Jw
b3JhdGUuYW1hem9uLmNvbYIRYnV5Ym94LmFtYXpvbi5jb22CEWlwaG9uZS5hbWF6
b24uY29tgg15cC5hbWF6b24uY29tgg9ob21lLmFtYXpvbi5jb20wCQYDVR0TBAIw
ADAOBgNVHQ8BAf8EBAMCBaAwHQYDVR0lBBYwFAYIKwYBBQUHAwEGCCsGAQUFBwMC
MGEGA1UdIARaMFgwVgYGZ4EMAQICMEwwIwYIKwYBBQUHAgEWF2h0dHBzOi8vZC5z
eW1jYi5jb20vY3BzMCUGCCsGAQUFBwICMBkMF2h0dHBzOi8vZC5zeW1jYi5jb20v
cnBhMB8GA1UdIwQYMBaAFF9gz2GQVd+EQxSKYCqy9Xr0QxjvMCsGA1UdHwQkMCIw
IKAeoByGGmh0dHA6Ly9zcy5zeW1jYi5jb20vc3MuY3JsMFcGCCsGAQUFBwEBBEsw
STAfBggrBgEFBQcwAYYTaHR0cDovL3NzLnN5bWNkLmNvbTAmBggrBgEFBQcwAoYa
aHR0cDovL3NzLnN5bWNiLmNvbS9zcy5jcnQwDQYJKoZIhvcNAQELBQADggEBAKeH
/SiREeFlL0ce/UDYoPDU/91x8XsbJuLRqxm1zEBzq/07/Fnd4nL/rayEEFIEubRS
IL9Ewi+htMz2nLrR0BMu3ilqWGhpOEvkcgT9uh/CjhPhVMse0lpHYSn62ZvUWTwn
vG0ardOd5MuE2NiveZxl3/o2cLcyiySxtX7N3yADchGP27iOkjXocdpZwtjIa7EB
pp3GojEbWRbGxtLC7SO3vY4a0N2bb5b9J7y5OtSKjInRJaMs19pFwlHMOMZR0y70
rHaz9eRB++LuEI2B90Mqr33NMysb1enMo61Dt16Ki3yT1zVBHp1vbqM6gX2UeEMA
A+HEDpMefyQVspV7twA=
-----END CERTIFICATE-----

Example output:

SEQUENCE
   SEQUENCE
      [0]
         INTEGER
      INTEGER
      SEQUENCE
         OBJECT IDENTIFIER
         NULL
      SEQUENCE
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               PRINTABLESTRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               PRINTABLESTRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               PRINTABLESTRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               PRINTABLESTRING
      SEQUENCE
         UTCTIME
         UTCTIME
      SEQUENCE
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               PRINTABLESTRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               UTF8STRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               UTF8STRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               UTF8STRING
         SET
            SEQUENCE
               OBJECT IDENTIFIER
               UTF8STRING
      SEQUENCE
         SEQUENCE
            OBJECT IDENTIFIER
            NULL
         BIT STRING
            SEQUENCE
               INTEGER
               INTEGER
      [3]
         SEQUENCE
            SEQUENCE
               OBJECT IDENTIFIER
               OCTET STRING
                  SEQUENCE
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
                     [2]
            SEQUENCE
               OBJECT IDENTIFIER
               OCTET STRING
                  SEQUENCE
            SEQUENCE
               OBJECT IDENTIFIER
               BOOLEAN
               OCTET STRING
                  BIT STRING
            SEQUENCE
               OBJECT IDENTIFIER
               OCTET STRING
                  SEQUENCE
                     OBJECT IDENTIFIER
                     OBJECT IDENTIFIER
            SEQUENCE
               OBJECT IDENTIFIER
               OCTET STRING
                  SEQUENCE
                     SEQUENCE
                        OBJECT IDENTIFIER
                        SEQUENCE
                           SEQUENCE
                              OBJECT IDENTIFIER
                              IA5String
                           SEQUENCE
                              OBJECT IDENTIFIER
                              SEQUENCE
                                 UTF8String
            SEQUENCE
               OBJECT IDENTIFIER
               OCTET STRING
                  SEQUENCE
                     [0]
             SEQUENCE
                OBJECT IDENTIFIER
                OCTET STRING
                   SEQUENCE
                      SEQUENCE
                         [0]
                            [0]
                               [6]
             SEQUENCE
                OBJECT IDENTIFIER
                OCTET STRING
                   SEQUENCE
                      SEQUENCE
                         OBJECT IDENTIFIER
                         [6]
                      SEQUENCE
                         OBJECT IDENTIFIER
                         [6]
SEQUENCE
   OBJECT IDENTIFIER
   NULL
BIT STRING

Helpful ressources

• Reference parser
• TODO: Add more useful links and actual ASN.1 parsing description

Answer 25

Simple Substitution Cipher Programming

A simple substitution cipher maps each unique character to another character. If my substitution cipher is [H->6, e->U, l->V, o->)], then Hello becomes 6UVV).

You must write a program A which inputs a string of text, and outputs the text after passing it through a substitution cipher.

You must also be able to handle your program, A, as input, printing out B. If possible, B then applies a different cipher, and prints out C, and so on, until you cannot repeat the process anymore, or until a duplicate program as been generated.

Your ciphers must:

1. Contain at least 2 substitutions, and every character in your program.
2. Change every character (i.e., no A->A)
3. Be unique on every substitution (i.e., if program A uses x->y, then program B must convert x into something other than y)
4. All be written in the same language (same version)

Your score is ByteCount(A)/NumIterations. You can assume that your input only consists of substitute-able characters.

For example, if A was Programming, and it generated p80G8AMM1NG, which generated u79)7%vvQ-), which finally generated Programming, then there were 3 ciphers applied, and a byte count of 11, so my score would be 11/3, or approximately 3.666667. If the final output was an invalid program, my score would still be the same.

Answer 26

Peano's quine

Your task is to write two programs in the same programming language.

The first program is simply a quine, in the following called "zero quine".

The second program, called succesdor program, is a program that gets a program text as input, and outputs another program text, according to the following rules:

• The input text is either the zero quine, or code that is (or could be) the output of another run of the successor program.

• The output is again a quine in the same language.

• The zero quine, generated quines and successor program fulfil Peano's axioms. In particular:

  1. The successor function does never output the zero quine, no matter what the input is.

  2. The successor function produces different output when acting on different valid input.

In other words, the zero quine and the successor function together allow to generate an unbounded number of quines, one for each natural number.

The score is the total number of bytes of the zero quine and the successor program together.

Note that while there are several challenges that have programs returning longer versions of itself when run, I didn't find any that has a program transforming a proper quine into another proper quine.

Tags: code-golf quine

Answer 27

Three-way meta-quine polyglot code-golf

Produce a program A such that running it in language A produces Program B, and running program A in language B produces program C.

Program B, when run in language B produces Program A, and running program B in language A produces program C.

Program C, when run in language A or language B, prints "Wrong language!".

Program | Language | Result
--------|----------|----------
A       | A        | Program B
B       | B        | Program A
A       | B        | Program C
B       | A        | Program C
C       | A        | "Wrong language!" 
C       | B        | "Wrong language!" 

Your answer should use this template:

---

Language A/Language B, {a bytes} + {b bytes} = {total bytes} bytes

Language A:

a code

Language B:

b code

---

Source:

# Language A/Language B, <a bytes> + <b bytes> = <total bytes> bytes

Language A:

    a code

Language B:

    b code

---

• None of these programs should take input.
• Different versions of the same language count DO NOT as different languages. - Languages A and B must be distinct.
• You must not read your own source code from a file. Programs may not be empty
• Standard loopholes apply.

This is code-golf, the smallest sum of the byte counts Program A and B wins.

Answer 28

Match the BF output code-golf regex brainfuck

Your task is, when given a BF program as input and 256 1's on the line after the BF program, match the amount of 1's equal to the value of the pointer when the program halts.

For a BF tutorial, see here.

Example programs:

+++
(255 1's)

(The above program should match 3 1's.)

++[>+++>+++<<-]>
(255 1's)

(The above program should match 6 1's.)

Specs:

• The tape in question is 10 long, with wrapping.
• There is wrapping for the individual values: if it goes over 256, it goes back to 0.
• There is no , or . in the BF code.
• You are guaranteed that the code will terminate.
• You may use any flavour you want.
• You may match 1's in any position, as long as you match the correct amount of 1's.

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

Meta stuff:

• How hard would this be to pull off? Is it even possible?
• Anything I could improve with explanations?

Answer 29

Find the highest product in a grid

The following problem was inspired by Problem 8 at Project Euler.

Write a program that takes a 2-dimensional block of digits and a number on a newline ("n") as it's input. Output value of the product of the n adjacent (read "in a straight line") digits in the that have the greatest product. Error cases don't need to be covered (eg. the grid is not rectangular, n is missing, n is bigger then the width/height as the block, etc.). Diagonal numbers are also adjacent.

Examples:

1932       
4836       
8490  -->  288
3          

53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881  -->  5832
16427171479924442928230863465674813919123162824586
4

43289
90283
03248  -->  error (print whatever)
34290
22

397432008949201741720 --> 72
2

Note: possible inputs below are equivalent:

2830
0309
8011 
4

2 8 3 0
0 3 0 9
8 0 1 1 
4

{{2, 8, 3, 0},
{0, 3, 0, 9},
{8, 0, 1, 1}}
4

And so on, it's not strict.

It's code-golf, so the shortest answer in bytes wins!

---

code-golf

Answer 30

Absolutely correct !

I have been given some homework, in which my Math teacher wants me to figure out what expression is represented in the graphs she gave me. Because it is long and painful to do every single one of them by hand, I want to automate it a bit.

The challenge

Given a graph as an input, output the equation represented, in human-readable format. That is, something like that:

y=-|x-3|+5

More generaly, the expression will always be of the form

y=±|x+a|+b

Where you have to replace a and b by their value. The function has to be simplified to its maximum (i.e. can not contain +0, -0, or +|x|);

The input

The input is given in ASCII.

             \       |       /             
              \      |      /              
               \     |     /               
                \    |    /                
                 \   |   /                 
                  \  |  /                  
                   \ | /                   
                    \|/                    
---------------------V---------------------
                     |                     
                     |                     
                     |                     
                     |                     
                     |                     
                     |                     
                     |                     
                     |                     

This represents the equation y=|x|. The graph is not always centered, and can be of any width and height.

/, \ are straight lines. A and V are verteces. - and | are the axes, and + is their intersection (if not covered by an other character).

Unit

A unit is two characters. for example, -- is one unit on the horizontal axis.

|
|

Is one unit on the vertical axis.

Tests

A test suite is available here. A line of #s is used to separate input from output. Output goes first, for clarity.