Sandbox for Proposed Challenges

Question

What is the Sandbox?

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

To post to the Sandbox, scroll to the bottom of this page or click on the "Add Proposal" link below, and click "Answer This Question". Click "OK" when it asks if you really want to add another answer. Write your challenge just as you would when actually posting it. You may also add some notes about specific things you would like to clarify before posting it. Other users will help you improve your challenge by rating and discussing it. When you think your challenge is ready for the public, go ahead and post it, replace the post here with a link to the challenge and delete it.

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Answer 1

The incremental Gijswijt's sequence

The Gijswijt's sequence G is a sequence where the next term is the maximal number of repeating blocks of terms going so far backward.

The first numbers of this series are: 1, 1, 2, 1, 1, 2, 2, 2, 3

The incremental Gijswijt's sequence I is a sequence of Gijswijt's indices where any term of this last sequence I(n) has an image in Gijswijt G(I(n)) that is greater or equal all terms that precede it in that sequence G .

In other terms, It is an increasing sequence of indexes i for which G(i) is at least as large as G(j) for any j < i. Thus it contains the index of every 1 up to the first 2, every 2 up to the first 3, etc

Example:

  G= 1, 1, 2, 1, 1, 2, 2, 2, 3, 1, 1, 2, 1, 1, 2, 2, 2, 3, 2, 1, 1, 2, 1, 1, 2, 2, 2, 3, 1, 1, 2, 1, 1, 2, 2, 2, 3,...

  I= 1, 2, 3,       6, 7, 8, 9,                        18,                           28,                        37,...

Your program must output the most you can print from the starting of sequence until the delay between printing two consecutive terms exceeds 10 minutes, the actual number of outputs is your score.

For matter of reliability, the complete accurate "run-lengthed" G sequence must be linked through pastbin or any raw data repository.

the output will be so large to fit an int32 registry, so i suggest to print it modulo 1000007 or dont.

if the scores are not be divergent enough i will apply some salt, scoring is evaluated to N/T where T is executon time in seconds for the last term of sequence, the tie broken by the earlier post .

Only another 45 secs after the delay cap are given as an extra time.

code-challenge

Answer 2

Inverse Square Probability

code-golf

It's a fairly well-known fact that the sum of the reciprocals of squares is equal to pi squared divided by 6. That is,

This is the Basel problem and was solved by Euler in 1735. I was thinking about generating a random patchwork of squares and trying to decide how to weight the probabilities of different square sizes, when it occurred to me that I could use this fact and make the probability of choosing a square's size be the inverse of its size.

For instance, if I pick a random point on the interval [0..pi^2/6), then based on the point I pick, r, I can translate it to a square size in the following manner (all numbers rounded to 3 decimal places):

0     <= r < 1     => s = 1
1     <= r < 1.25  => s = 2
1.25  <= r < 1.361 => s = 3
1.361 <= r < 1.424 => s = 4
1.424 <= r < 1.464 => s = 5
...

Your program or function should work for any input within the limits of your language (for instance, floating point precision, lack of built-in bignum capabilities, etc). Input will always be 0 <= r < pi^2/6.

Test Cases

{to be added}

Answer 3

Functional Programming in Your Language

A lot of modern programming languages allow some form of functional programming, but I don't often see them used. I'm curious to see how different languages tackle problems that are naturally solved with some form of functional programming. The winning entry to this contest will have the shortest total code as measured in bytes for these four questions

1. Given a three-part list, return a list containing only those members for which the third element is a string.

   sampleIn1={{1,2,"fred"},{3,2,1.23},{3,2,"this one too",1.23},{},{"apple","banana",{1,2,3}}}

   sampleOut1={{1,2,"fred"},{3,2,"this one too",1.23}}

2. Given a list of lists, each sub-list known to have exactly two elements, both of which are numbers, return a list of the first element in each sublist multiplied by the absolute value of the second.

   sampleIn2={{3,4},{-1,3},{1.0,-3}};

   sampleOut2={12,-3,3.0}

In the sample output above I distinguish between integer and real output; in practice you can treat everything as a real number if you prefer.

3. Given a list known to be composed only of numbers, return a list of the cube of each member, sorted by the square of each member (or its absolute value, which will have the same result).

   sampleIn3={1,-2,0.5,4};

   sampleOut3={.125,1,-8,64}

4. Given a list known to be composed only of numbers, return a list with each member of the list divided by the number before it. Since this is undefined for the first number in the input list, that element should be omitted. Where division by zero would result, the list should include notification of exception ("N/A" or something similar as befits your language of choice).

   sampleIn4={1,-2,0,5,4};

   sampleOut4={-2,0,"N/A",0.8}

Presume that input has been assigned to a variable a in the natural list format for your language, assuming it has one.

To be clear, you don't have to use abstract functions or lambda calculus here, though I suspect that in many languages this will provide a short solution.

Standard rules apply, the examples above are only examples. Your code should work for arbitrary input.

Answer 4

ASCII Hulls

code-golf ascii-art geometry

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Input

A string containing a rectangle made up of m rows of n characters, separated by newlines. Apart from an optional trailing newline (which you may choose), the string must contain nothing else.

All the characters will be printable ASCII (including space). So ASCII characters 32 to 176 inclusive.

The dimensions m and n will not be specified in the input. They will both be in the range 1 to 80 inclusive.

Output

A string containing the same rectangle but with the convex hull of each non-space character filled with that character, higher ASCII values overwriting lower ones.

Overwriting does not prevent a character from contributing to the convex hull. For each character, the convex hull is defined based on the locations of that character before any overwriting.

Details

The rectangle of characters forms a grid of m squares by n squares. The vertices of the convex hull for a given character are the centres of the squares containing that character (apart from any in the interior of the convex hull). All squares whose centre is on the convex hull or in its interior become that character (until any overwriting).

Equivalently you can use the top left corner instead of the centre (or any other point in the square) provided it is consistent. This will give the same output.

Test cases

Input followed by output in a single code block

P    
   P
 P  

P    
 PPP
 P

C    C

      G    G
    C    C

   G    G

CCCCCC
  CCCCC
   CCCGGGGGG
    CGGGGGG
    GGGGGG
   GGGGGG

 W    Z
X      X


Y      Y
 W    Z

 W    Z
XXXXXXZX
 W    Z
 W    Z 
YYYYYYZY
 W    Z

Scoring

The shortest code in bytes wins.

Answer 5

Shortest path to the exit:

• Given a n*n grid of 3 symbolic characters {'.','#',*} , where n is inputted, the dot is a safe spot to move from/to, # is a dragon who blows fire and spits magma, * is the outlet . Define (if it can be) the shortest path to take from the extreme upper/right to the star character that a moving point can take where:

  m is an integer m < n given by user-input or a function dimention with n, that generates obstacles # at the dynamic point m modulus n from the starting point, the last # point so far is replaced by an exit *, if no such path exists print 0 or a negative amount or undifined/null anything witch doesnt throw an error.

Testcases:

input: 7,3
output:9

why? the input generates this grid

...#...
#...#..
.#...#.
..#...#
...#...
#...*..

The shortest path is marked as _

__.#...
#__.#..
.#__.#.
..#__.#
...#_..
#..._..

More TODO ...

Hints/notes

• Solution is cyclic

• No solutions when m+1 divides n or n-1 . (to verify)

Answer 6

Triangle Rasterization

I don't know if this is the right word for this, but here goes...

Given a triangle with a height and a width, you can convert it into squares by counting any square that the triangle occupies as a whole square. Your task is to calculate the area of this 'rasterized' triangle.

Your program should take two positive integers representing the height and width of a triangle and output the area of its 'rasterized' version. This should always be an integer.

No builtins are allowed, if there are any.

An example

This is a 6x4 triangle. The red area is the actual inside of the triangle, and the blue area is added on during the 'rasterization'. The total are of the red and the blue is 16. So, given 6 and 4 as inputs, your program must output 16, with or without a trailing newline.

Test cases

 input     output
 1, 1      1
 1, 2      2
 1, 3      3
 2, 2      3
 6, 4      16
 63, 47    1512

As you can probably tell, this is slightly larger than half the area of the enclosing rectangle, and gets more accurate for larger sizes.

Your program should preferably run in under a minute, but the answer with the shortest number of bytes will win.

code-golf

Answer 7

"45-degree rotation" of a square matrix

code-golf matrix

---

Introduction

Suppose we have a square matrix with odd sidelength, like this:

0 1 2 3 4
5 6 7 8 9
0 1 2 3 4
5 6 7 8 9
0 1 2 3 4

Let's divide it into nested layers as follows:

0 1 2 3 4
 +-----+
5|6 7 8|9
 | +-+ |
0|1|2|3|4
 | +-+ |
5|6 7 8|9
 +-----+
0 1 2 3 4

The nth layer, counting from the center, contains 8*(n-1) cells, and we rotate it n-1 steps in the clockwise direction:

0 5 0 1 2
 +-----+
5|1 6 7|3
 | +-+ |
0|6|2|8|4
 | +-+ |
1|7 8 3|9
 +-----+
2 3 4 9 4

Now our original matrix has been "rotated by 45 degrees", in a sense:

0 5 0 1 2
5 1 6 7 3
0 6 2 8 4
1 7 8 3 9
2 3 4 9 4

Namely, if this operation is applied twice, the result is a 90-degree rotation.

The task

Your input is an n×n matrix of single-digit integers, where n is odd, in any reasonable format. Your output is the 45-degree rotation of this matrix, as defined above.

Rules and scoring

You can write a full program or function. The lowest byte count wins, and standard loopholes are disallowed.

Test cases

[[3]] -> [[3]]
[[1,2,3],[4,5,6],[7,8,9]] -> [[4,1,2],[7,5,3],[8,9,6]]
[[0,1,2,3,4],[5,6,7,8,9],[0,1,2,3,4],[5,6,7,8,9],[0,1,2,3,4]] -> [[0,5,0,1,2],[5,1,6,7,3],[0,6,2,8,4],[1,7,8,3,9],[2,3,4,9,4]]
[[1,0,0,2,0,0,3],[0,1,0,2,0,3,0],[0,0,1,2,3,0,0],[4,4,4,5,0,0,0],[4,4,4,4,0,0,0],[4,4,4,4,0,6,7],[4,4,4,4,0,8,9]] -> [[4,0,0,1,0,0,2],[4,4,0,1,0,2,0],[4,4,4,1,2,0,0],[4,4,4,5,3,3,3],[4,4,4,0,0,0,0],[4,4,0,6,0,0,0],[4,0,8,9,7,0,0]]

Answer 8

KOTH Screeps Fighting AI king-of-the-hill

Screeps is an MMO for programmers (not a regular MMO, this is not modding, but rather the only way to play) where you program creeps. I want to make sure one more time: this is not hacking or modding, this is the only way you play the game. It has a builtin IDE that is always present.

This is your job: With 1550 energy, spawn an army of creeps to fight other player's armies. Your goal is to destroy the other team's spawn.

Specifications

• Each team will start with 0 creeps and it's own spawn.
• The team number will be hardcoded.
• The spawns will be named Spawn1 and Spawn2, corresponding to each player's team
• The room controller will be at level 8 and you will not have to worry about upgrading it.
• Each creep will display an emoji chosen to represent it's team using creep.say(). This is so that members of the two teams can distinguished.

Rules

• Not all creeps have to fight. Some can gather energy, build walls, etc.
• Building structures is allowed. This includes walls, ramparts, towers, etc.

This is under construction! Please comment if you know how to improve this challenge!

Answer 9

Kill the mosketeers

Taken a NxN square field, where you are supposed to be on the extreme upper right corner, n mosketeers are waiting an execution instruction that begins with the first lefttmost shooter alternatively until the last righttmost one, in a continuous unceasable order, meanwhile, between any shot and another you are allowed to move one step either to 4 allowed perpendicular directions.

T a period permitted to reload the riffle from a shot to another, dependently of steps taken from a move to another, a step is expressed in other words, as the time taken from two consecutive shots that of a mosketeer and his neighbor, so once T steps are elapsed, the mosketeer takes turn to shot again where two shots can occur in real-time.

Your task, is more than saving your head on your shoulders, but it is rather the ability of killing all the mosketeers while they are reloading their riffles by a knife, noted that : a mosketeer can shot in an horizontal dimention if his turn comes out, and no moketeer is between him and you, morover, a mosketeer do never move.

Given two inputs, N T, say in term of integer output how many mosketeers you are able to kill, return -1 or nil the case you end up killed no matter what you tried.

Example:

input:

   4,3

steps:

...*  |... .|.. ..|. |..| .|.. ..|. |..| .|.. ..|. ...| .... ....
....  |..* .|.. ..|. |..| .|.. ..|. |..| .|.. ..|. ...| .... ....
....  |... .|.* ..|* |.*| .|*. .*|. |*.| *|.. ..|. ...| .... ....
$$$$  |$$$ $|$$ $$|$ |$$| $|$$ $$|$ |$$| $|$$ *$$$ .*$| ..*$ ...*

Output:

  4

---

example 2

input:

   4,2

steps:

...*  |... .|.. |.|. .|.| |... .|.| |... .|.| .... .|.| 
....  |..* .|.. |.|. .|.| |... .|.| |... .|.| .... .|.| 
....  |... .|.* |.|* .|*| |... .|*| |*.. *|.| .... *|.| 
$$$$  |$$$ $|$$ |$|$ $|$| |$*$ $$.$ $$.$ $$.$ *$.$ .$.$ 

Output:

  2

---

Answer 10

Serialize and Deserialize a Binary Tree!

code-golf

A coding website, leetcode.com, has a method to serialize a binary tree.

Serialize means making a binary tree linear.

For example, we have:

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

    1
   / \
  2   3
     / \
    4   5

First, we fill the missing places with 0:

      1
     / \
    /   \
   /     \
  2       3
 / \     / \
0   0   4   5

Then read out all the lines from top to bottom:

->      1
       / \
      /   \
     /     \
->  2       3
   / \     / \
-> 0   0   4   5

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

Let's look at another example:

   1
    \
     2
    /
   3

Fill the missing places with 0:

   1
  / \
 0   2
    / \
   3   0

Note that 0 cannot have any child.

Therefore, this tree is serialized as [1,0,2,3,0].

Your task is to write two programs/functions, one to serialize, one to deserialize.

Specs

• They may share code.
• The binary tree will only contain positive integers.
• A node in the binary tree is represented by [name,left_child,right_child].
• You may not pre-fill the binary tree with 0s.
• [1,0,2,3,0,0,0] is invalid.
• Unlike the website given, [1,0,2,3] is invalid.

Notes

• Subset of this challenge, but this is code-golf instead.

Answer 11

Matching a string using a huge number of steps

regular-expression code-challenge

Your task is to write a regex that matches a string you defined in as close to n steps as is humanly possible.

The regex must match the whole string without the global flag on.

Scoring

The score would be regex length + string length + absolute difference between the number of steps and n.

For example, if n = 65536, this example has 6 bytes as regex, 49152 bytes in the string, and 65539 steps, which would account for a total score of 6+49152+3=49161.

Lowest score wins.

Requirements

1. n = 65536 (2**16)
2. n = 59049 (3**10)
3. n = 40320 (8!)

The total score will calculated from the scores of the three programs.

Questions:

• How can I make this challenge better?

Answer 12

Brainfuck-golf: find the maximum of two numbers

tips

You will be provided with two numbers on the first two memory cells, and you will write a code in brainfuck to put the maximum of the two numbers on the third memory cell.

• You may use this template and this template to test your code. Just append your code to the templates.
• You may destroy the numbers in the first two cells.
• The pointer must initially point to the first cell.
• The two initial numbers will be positive.
• , will halt your program (waits for input which I will not supply).
• The tape is semi-infinite. Your numbers are on the first two memory cells.
• The cells do not wrap around. They just increase until the number is bigger than the age of the universe in terms of picoseconds.

Answer 13

Primary Chances

Write a program that lists all possible outcomes for a general election with any number of candidates.

Rules:

• Your answer must output how many states each candidate won in any format.
• Candidates can have any name.
• This is code-golf, so standard loopholes are forbidden, and shortest code wins.

Answer 14

Sort 2D points by Sierpiński curve order

code-golf geometry fractal sorting

---

[ WORK IN PROGRESS]

---

Input

A collection of distinct 2D points in the range [0,1] X [0,1].

Output

An ordered collection of the same 2D points, meeting the criteria for Sierpiński curve order.

Sierpiński curve order

• The points are in the order that the Sierpiński curve would pass through them.
• The order is cyclic - it does not matter which point is first.
• The order may be clockwise or anticlockwise/counterclockwise, provided it is consistent.
• The point at the centre of the range, (0.5, 0.5), may fall into any triangular quarter of the range, provided it is in the correct order among other points in that quarter. Similarly for all other points where both coordinates have finite binary expansion.

Although the curve is infinitely long and fills the unit square, it is arranged in a convenient shape that allows ordering points by calculating only a finite number of iterations. For example, if there are 4 points, one in each triangular quarter of the square, then they can be ordered based only on this information as the curve fills one triangular quarter before moving on to the next so the exact position without that quarter is not relevant.

---

Sandbox questions

• Should ambiguous points be allowed to fall in any direction, or should I impose that they always fall left rather than right and up rather than down? Or just insist that the solution choose a consistent direction rule?
• Can I assume that any three points that can be described by floating point variables can be ordered in a finite number of subdivisions? I'm pretty sure but welcome a counterexample.

Answer 15

Find ALL Longest Common Substrings

Unlike "Longest Common Substring" algorithm which returns just one string, or the length of it. This algorithm returns a score after taking all separate longest common substrings into account.

This program returns the score of how similar one string is to another according to the following rules:

1. isolate only the longest (non-overlaping) matching substrings.
2. score every longest substring found with this formula: (substring.length / ((string1.length + string2.length) / 2)) * substring.length
3. sum the scores and return.

STEP 1 Example:

string1 = ABCD

string2 = ZBCA

Deconstructing string1: (list of substring in order)

ABCD

ABC

AB

A (also found in string2)

BCD

BC (also found in string2)

B (also found in string2 but ignored - part of a longer substring)

CD

C (also found in string2 but ignored - part of a longer substring)

D

Matches: A, BC

STEP 2 Example: (substring.length / ((string1.length + string2.length) / 2)) * substring.length

A: (1/((4+4)/2)) * 1 = .25

BC: (2/((4+4)/2)) * 2 = 1

Step 3 Example:

.25 + 1 = 1.25, Return 1.25

Here's an example of longer strings of variable length:

string1 = Approximate This

string2 = Appropriate That Thing

Matches: Appro, i, ate Th,  Thi

Appro: (5/((16+22)/2)) * 5 = 1.3157894736842105263157894736842

ate Th: (6/((16+22)/2)) * 6 = 1.8947368421052631578947368421053

i: (1/((16+22)/2)) * 1 = 0.05263157894736842105263157894737

 Thi: (4/((16+22)/2)) * 4 = 0.47368421052631578947368421052632

Return: 4.1052631578947368421052631578948

Answer 16

Fizzbuzz for tensorflow

Since I was a new and naive user, I posted this question. In one day it got over 25 upvotes but was shut down for being too broad. Clearly there is community interest -- so by the suggestion of @DrGreenEggsandHamDJ I'll try it again in the sandbox. I'd really like to see some of the answers here, so I appreciate any help you can give turning this question into a proper submission.

Original text copied below:

---

Inspired by the job-interview with Joel Grus, the goal of this challenge is to write a tensorflow (or other deep/machine learning) program that learns Fizzbuzz and correctly prints out the answers to the positive integers less than 1000.

You can assume there are files named train.csv and test.csv and each contain a sorted list of sequential integers and the fizzbuzz answer:

 ...
 100, buzz
 101, 101
 102, fizz
 103, 103
 104, 104
 105, buzz
 ...
 150000, fizzbuzz

test.csv spans 1-1000 and train.csv spans 1001-150000.

Rules

1. You must not hard-code the rules to Fizzbuzz anywhere in your program. The output must be from a machine learned representation that is learned while running the code.
2. You must utilize train.csv in the training set and check your output against test.csv. You cannot use test.csv during training.
3. You must get all outputs correct from test.csv (but as is case with deep-learning, we'll allow your code to fail this rule no more than 5% of the time).
4. You may use any language and any external module (eg. python/tensorflow) as long they explicitly perform some kind of learning. Reference both the language and the module in the title of your post.
5. This is a popularity contest, so the submission with the most votes after one week wins.

Answer 17

What can I build? code-golf

The Rules

Today I have decided to make geometric shapes out of toothpicks and gumdrops! However, I have a limited supply, so you have to figure out what I can build. I will give you an input in the format m n, where m is toothpicks (edges) and n is gumdrops (vertices.) Your output should be, in any output format of your choice, all 3D geometric shapes such that the amount of edges=m and the amount of vertices=n. The list of 3D geometric shapes you will use is this: Gist

• You may NOT access the Internet.
• No builtins relating to geometry or solids
• This is code golf, so shortest code wins.
• For no solids and invalid input, output nothing

Examples

In: 3 2 Out: <empty>
In: CodeGolf123 Out: <empty>
In: 12 6 Out (Bonus): {regular tetrahedron,unit equilateral square pyramid,unit equilateral triangular dipyramid,unit equilateral triangular prism,unit equilateral pentagonal pyramid,regular octahedron} Out (Regular): {regular octahedron} `

Answer 18

Code me music

Challenge

Write a program that will play music based on input.

Input

When your program is run it will be given a small song. Each note in the song will have 3 components:

[octave][pitch][duration]

where octave is the octave for the note to be played in, pitch is the key of the note (a b c d e f g), and duration is the length of the note in milliseconds. For example, 4c1000 would be middle c played for one second. Notes in a song are separated by spaces. Flats and sharps are possible, and they go after the note like this: 5gb1000 (5th octave g flat) for flats and 5g#1000 (5th octave g sharp) for sharps.

Output

Your program must produce sound based on the input. If one of the notes in the input is 3f500, your program must play f in the third octave for a half of a second.

Other notes

• This is code golf, so shortest program in (insert period of time) wins.

• No functions, only full programs.

• The sound can be whatever you please.

• Here are the frequencies of notes in the 4th octave in hertz:

  • 4c - 261.63
  • 4c#/4db - 277.18
  • 4d - 293.66
  • 4d#/4eb - 311.13
  • 4e - 329.63
  • 4f - 349.23
  • 4f#/4gb - 369.99
  • 4g - 392.00
  • 4g#/4ab - 415.30
  • 4a - 440.00
  • 4a#/4bb - 466.16
  • 4b - 493.88

• A list of all frequencies is here.

Sandbox

• Is the challenge objective clear?
• This challenge may be hard for some languages, is that a problem?
• Is this already a challenge?
• Any positive feedback is welcome.

Answer 19

Plan a special tournament

tags: code-golf [more tags required]

---

I host a special tournament with any number n >= 2 of participants.

Here is a list of plans of tournaments for n = 2 to 20:

 2: 1) DE-2c-1w
 3: 1) RR-3c-1w
 4: 1) DE-4c-1w
 5: 1) RR-5c-2w 2) DE-2c-1w
 6: 1) RR-6c-3w 2) RR-3c-1w
 7: 1) RR-7c-3w 2) RR-3c-1w
 8: 1) DE-8c-1w
 9: 1) RR-9c-4w 2) DE-4c-1w
10: 1) RR-10c-5w 2) RR-5c-2w 3) DE-2c-1w
11: 1) RR-11c-5w 2) RR-5c-2w 3) DE-2c-1w
12: 1) RR-12c-6w 2) RR-6c-3w 3) RR-3c-1w
13: 1) RR-13c-6w 2) RR-6c-3w 3) RR-3c-1w
14: 1) RR-14c-7w 2) RR-7c-3w 3) RR-3c-1w
15: 1) RR-15c-7w 2) RR-7c-3w 3) RR-3c-1w
16: 1) DE-16c-1w
17: 1) RR-17c-8w 2) DE-8c-1w
18: 1) RR-18c-9w 2) RR-9c-4w 3) DE-4c-1w
19: 1) RR-19c-9w 2) RR-9c-4w 3) DE-4c-1w
20: 1) RR-20c-10w 2) RR-10c-5w 3) RR-5c-2w 4) DE-2c-1w

Explanation of the plan

• The entire tournament enters the first round, which has c = n participants.
• For each round:
  • If c is a power of 2, then this round will be a double elimination round, with 1 winner. After this round, the tournament ends.
  • Else, this round will be a round robin round, with floor(c/2) winners that continue to the next round.
    • If only one winner continues, the tournament ends.
    • Else, let c be the number of winners, and start again from "For each round".

The Challenge

Given n, return a plan of the special tournament with n participants.

This is a code-golf, so shortest code wins.

TODO: Reword the explanation clearly, write more content.

Answer 20

Golf a 2d maze (Yes, a whole game)

Nowadays, I am interested in making games. especially mazes. In this golf round of code, You should make a maze game. You can do it with just preset mazes, but, if you make it randomly generate, I will be a-maze-d and will give you bonus points.(Huh. is that a pun?) So, Go on, Why don't you try right now?

DETAILS:

• Input W(Up), A(Left), S(Down), D(Right) until the player gets to the finish.
• Display the maze and the player each input.
• Move the player Up if the input is 'W', Down if 'S', Left if 'A', and Right if 'D'.
• The Character for the wall and the player is undefined. you choose.
• The Character for the wall, the player and the end square should be all different.

MAZE GENERATING:

• You should get the Width and height in the input.
• Not Necessary, but you can use Prim or Kruskal.
• Also you can use the method mentioned in here.

Answer 21

Light black box: generate mirror processors

code-challenge

[ WORK IN PROGRESS - LOTS OF OUTSTANDING QUESTIONS ]

---

Input

The list of black box output values for all black box input values from 0 to 255 (inclusive), in any reasonable format. Each value is also in the range 0 to 255.

Output

A text representation of a rectangular grid showing the locations and orientations of mirrors that will generate the appropriate black box output for each black box input.

Specification

• The input bits arrive from the left of the grid, in the top 8 squares, initially travelling right.
• The output bits depart from the right of the grid, in the top 8 squares, travelling right.
• For both black box input and black box output, the most significant bit is at the top.
• Bits move through the grid horizontally or vertically until they encounter a mirror or the edge of the grid.
• Bits that leave the edge of the grid are lost.
• A bit that would move onto a mirror at the next step instead changes direction by 90 degrees clockwise or anticlockwise according to the mirror type, and takes a step in that direction (a bit never stays on the same square).
• If two or more bits arrive on the same square at the same timestep, all of them annihilate. Two bits can still pass through each other if this does not involve sharing a square (traveling in opposite directions, being adjacent facing towards each other on one step, and adjacent facing away from each other on the next).

Note that because a bit changes direction just before reaching a mirror, there cannot generally be a mirror in an input or output square, as this would prevent the bit entering/leaving by that square. However, a grid taking advantage of input/output that has no requirement for a given bit by placing a mirror that blocks a given input or output square is still valid provided it gives the correct behaviour.

Example

[ PENDING ]

Scoring

The score for each input is the area of the resulting grid. The total score will be the sum of the scores for each of the test inputs.

---

Sandbox questions

• Is this too similar to domino circuits? The photons leave no trail so they can cross over their own and each other's paths arbitrarily many times. Also a given mirror can affect arbitrarily many photons, and each an arbitrary number of times.
• Is this a duplicate of anything else?
• Should the score be just the area of the grid, or also include the time between input and output? The time will have to be the worst case over all inputs, as reading the input before then would give a false result in some cases.
• Should output bits have to arrive at the same time?
• Should the time from input to output be required to be constant over all inputs?
• There cannot be more output bits than input bits. Should test cases reflect this, or should a mechanism be introduced to make all patterns of output possible?
• Should the particles be referred to as "bits", "photons", or something else?
• Currently tie break is first posted. Should the number of mirrors be taken into account as a tie break first?
• Should the grid wrap? I initially thought not, but then I realised there would need to be an extra row above the I/O rows to allow mirrors to redirect onto the top output bit. It might be simpler to keep to having the I/O rows at the very top, and simply put redirecting mirrors in the bottom row. This would make it possible to redirect onto rows 0 and 7 with only 8 rows in total.
• I've chosen mirrors that change the bit's direction just before impact, rather than on impact. I liked the fact that this gives an asymmetry - reversing the direction will not reverse the route taken. This introduces the potential for sending a bit back along part of the same path without trivially sending it back to its origin. Is there any reason to stick to the symmetrical case instead?
• The other thought that occurred to me was to have the mirrors change direction too, flipping between the two possibilities at each impact.
• There are 256**256 possible ways to assign a value from 0 to 255 to each of 256 different inputs. This is far too large a space for hardcoding all solutions. However, this doesn't necessarily mean that the worst case grids will be huge. A lower bound on the worst case grid area is log(256**256,3), which is just over 1292 (since there are 3 possible states for each square). The maximal lower bound is likely to be far higher than that, but I have no idea how much higher. I'm likely to settle on a small enough space that code can be expected to deal with any input, but still a large enough space that hardcoding is impossible (I don't want to explicitly rule it out). (Here ** indicates exponentiation, as used in python.)
• Mirrors that split bits, and bits annihilate on collision with each other. This will allow for arbitrary input and output rather than being restricted by the initial number of bits. I'm considering a number of possible approaches:
  1. One mirror type only: always splits a single bit into two bits in the two directions perpendicular to the current direction.
  2. 4 mirror types - each having a dead direction. A bit arriving from that direction is destroyed. A bit arriving from any other direction is split into two bits, one for each remaining direction.
  3. 4 mirror types - each having a dead direction. A bit is only split into two bits if the two perpendicular directions are not dead. Otherwise only one bit is produced, in the available perpendicular direction (or no bits if the bit approaches from the dead direction).
• Can bits be left in the grid that do not terminate? Can a solution specify that the output should be measured at a set time, even if some bits will later reach the output squares altering the result? Should the output only be measured once all activity has ceased - excluding the possibility of using a repeating cycle?

Answer 22

Find the duration of a worst-case brute-force attack

Given the following information about a 7-bit ASCII-encoded password and the computer that will crack it with a brute-force attack:

• Length of the password in characters
• Charset size (i.e total count of the possible characters one character in the password can be)
• Number of passwords the computer can test in one second millisecond (rounded down)

Write the shortest program that finds out how long the attack will take in the worst-case scenario where the computer tries all possible passwords.

• The output is the duration in this format: years months days hours minutes seconds milliseconds
  • One "month" is 30 days long.
  • Fractions of milliseconds are rounded up.
  • You can assume that the cracking finishes immediately if it takes less than 50 milliseconds, and make the program print out Instant in such cases.
  • Similarly, the cracking can be considered Neverending if it takes more than 292 billion years.
• The program can output using any method, from merely printing to STDOUT to causing a kernel panic/bluescreen with the duration as the error message.
• The input method to get the info about the password/the machine can be anything, as well. Don't use standard loopholes though.
• It's not enforced, but strongly encouraged to write a standalone program.

Here's how to calculate the charset size:

• Start with 0.
• If there's a digit (in the password), add 10.
• If there's a lowercase letter, add 26.
• If there's an uppercase letter, add another 26.
• If there's punctuation, add 32 (7-bit ASCII has this many punctuation characters).
• If there's a whitespace character, add 2. Whitespace characters are horizontal tab (0x09) and space (0x20).
• Any other character counts as non-printable (including backspace (0x08), DEL (0x7F), line feed (0x0A) and carriage return (0x0D)). Add 29 if there's any of them.

Count of all possible passwords is (charset size)^{password length}.

Here are some applicable-in-real-life cases you can test your program with (let's assume the computer that will crack them can test 1 billion passwords per second, which equals to 1,000,000 passwords/millisecond):

• 4 characters, charset size 10 (PIN) - 10,000 passwords, output is 0 0 0 0 0 0 1 or Instant
• 8 characters, charset size 94 (at least one uppercase letter, one lowercase letter, one digit and one punctuation) - 6,095,689,385,410,816 passwords, output is 0 2 10 13 14 49 386
• 10 characters, charset size 2 (weakest valid Discourse password, contains whitespace only) - 1024 passwords, output is 0 0 0 0 0 0 1 or Instant
• 25 characters, charset size 26 (correcthorsebatterystaple) - 236,773,830,007,967,588,876,795,164,938,469,376 passwords, output is 7612327353651221350 2 14 0 26 4 939 or Neverending
• 127 characters, charset size 96 (strongest password on newer Windows releases) - written below
• 1024 characters, charset size 36 (4096-bit PGP key represented as a hexadecimal number) - written below

These are the stats of the maximum-strength Windows password:

Passwords: 560,333,510,486,846,899,384,847,242,571,130,277,659,458,884,466,874,695,582,912,274,460,529,559,443,783,341,570,989,525,270,653,136,186,432,110,439,597,936,820,880,106,519,625,601,191,574,799,863,912,148,304,962,133,852,037,202,160,056,511,510,962,873,278,300,126,526,144,267,006,137,180,032,492,751,016,171,207,701,495,935,943,049,216
Output: 18014837657113133339276210216407223432981574217685014647084370963880194169360318337544673523362047845500003550655797865897637169483847774934889398916928636347805229296463546812516445182705545212838429981490065783731353925307067135133992 5 15 19 58 55 944
Alternate output: Neverending

And these are the stats of the PGP key:

Passwords: 4,505,684,579,918,576,285,346,738,866,335,056,898,110,301,685,668,199,078,230,938,179,212,682,315,156,231,410,185,391,761,603,272,976,014,035,539,665,517,248,679,228,261,440,294,129,198,036,262,705,242,310,399,830,546,082,361,923,420,737,260,766,677,891,361,176,003,624,143,368,380,527,062,643,297,677,246,518,686,688,642,023,537,863,317,793,178,302,508,440,097,154,593,959,832,175,055,427,351,149,410,096,495,695,380,712,810,868,774,475,142,767,054,868,274,802,269,522,299,482,066,464,842,097,715,922,988,138,315,118,067,288,670,934,735,264,524,936,706,249,961,394,413,647,964,221,767,703,673,264,468,419,121,528,644,906,680,808,060,759,817,669,970,046,776,525,266,199,099,671,937,918,801,013,826,958,891,378,841,908,663,991,372,649,027,188,879,525,186,690,599,345,723,173,064,252,017,258,129,131,786,488,462,307,158,861,824,049,980,863,991,149,295,162,169,512,952,373,415,599,734,988,691,348,925,488,351,712,593,858,837,027,205,238,618,188,975,201,320,681,214,515,875,812,195,250,605,867,622,987,451,763,883,339,709,733,502,125,838,221,788,546,339,051,347,360,900,518,381,976,167,289,930,943,228,024,924,785,158,428,496,314,937,921,503,359,298,542,415,845,218,449,360,806,235,379,253,546,728,753,218,950,843,742,471,105,739,555,344,908,900,309,982,913,223,331,321,839,212,821,903,239,320,600,564,890,951,140,667,647,680,682,245,252,370,183,758,578,065,733,075,207,856,432,661,797,090,351,101,165,469,273,829,754,476,555,209,675,613,232,875,323,406,611,257,057,059,099,019,633,298,079,410,970,345,108,939,943,042,100,267,260,413,671,556,828,411,902,575,269,208,445,279,433,655,878,082,023,068,697,154,581,711,817,787,688,949,105,583,339,471,599,190,831,084,304,744,483,799,555,478,063,729,574,297,623,870,804,763,558,027,580,772,927,971,329,879,231,979,556,301,616,929,595,576,646,883,067,201,999,872,899,862,889,211,861,332,535,050,455,387,251,034,043,732,447,006,164,551,883,918,733,705,027,099,846,583,024,013,092,062,384,703,436,459,115,108,358,829,136,251,317,699,709,899,140,949,893,425,335,769,021,022,912,434,045,643,544,474,460,899,799,213,759,568,795,794,758,914,390,056,283,305,470,380,859,003,818,724,678,434,816
Output: 144858686339974803412639495445442930108998896787172038266169565946909796654971431654622934722327449074525319562291578211137739886840732034401886018044055761311424449664413690224320369299057721231224396352345948448015131278860508182828147139982752631922511354755096078964028889980704480936709984283352948061204198196785328857204061945957268141550998891534834171375541476907019128991072373909056348731183618329634024763694746476776233417623704464804027405450152026906721990999895827471385353870130056140660354679074035526421905828555132520211676677361401337091034117370453939870215183392876069255694823382473711006907851853458746913295694931911314073828877816349504523255816791677974298928074750103049081088894521647398444396729546431174466495229648516324713327536964168664025148591452750098101445502202880078966283755495859954505040675103796820824907455740718188735077328268047865426806174561044520100917915500979652319301547868727504821981520811835192875926630119576922600465887060849654310721522802609638109522185755307201898676461606130734024600227278608209698963323356340446015796148617903068964091403666193996894642822309315198786075754477250953946657292049336910661279747924178751224344877465829301109562043071275369906871767991229129085786546569052197642684662087651029574035646976531236521763373563846425925268656816387911380422031991615290633773786744123323731112880994579065426763237282889858685438654794679302568796507941872848896038602862540480809810919146613018187362072374644736799940064590439265446053422181856817801562474722208358918298576208528044087753034364036 10 24 22 32 4 679
Alternate output: Neverending

code-golfcryptographydate

Answer 23

Implement an HTTP Tunnel

I'm bored at work and stuck behind a draconian proxy.

They can take my other ports but they can never take my port 80 freedom!

Help me get all the internets!

This is a code-golf challenge.

requirements

• a single web page that processes GET and POST data and produces output
• if GET m=start
  • creates any files you feel are necessary (named pipes, scripts, what-have-you)
  • forks a process which will create a tcp connection
  • connects to host and port based on GET variables h and p
  • these variables should be cleansed so as not to allow command injection
• if GET m=in
  • write the raw POST data to your forked process's tcp connection
• if GET m=out
  • get all data available from the forked process's tcp connection and write as response
  • should always return right away (let's say, in less than 1 second)
• if GET m=stop
  • kill your forked process
  • clean up any files it has created

Test data

• http://servername/httptunnel?mode=start&host=ppcg.ga&port=80
• http://servername/httptunnel?mode=in
  • POST data: GET / HTTP/1.1\r\nHost: ppcg.ga\r\n\r\n

• http://servername/httptunnel?mode=out

  HTTP/1.1 301 Moved Permanently
  Server: nginx
  Date: Tue, 07 Jun 2016 02:03:14 GMT
  Content-Length: 0
  Connection: keep-alive
  Cache-Control: no-cache
  Expires: Thu, 01 Jan 1970 00:00:01 GMT
  Location: https://codegolf.stackexchange.com/
  Pragma: no-cache
  

• again, to prove the connection is still open, http://servername/httptunnel?mode=in

  • POST data: GET / HTTP/1.1\r\nHost: ppcg.ga\r\n\r\n
• and again, http://servername/httptunnel?mode=out
  • Content returned: same as before
• http://servername/httptunnel?mode=stop
  • system state returned to prior to the first http call

my first instinct was to have this challenge be three separate pieces of code, a client which listens on a port locally and interacts with the web page, the web page itself, and a script which will be forked by the web page. your score would be the sum of all their byte counts. i decided to remove the last as the start process would likely have to create other files so why not have it create the script to run as well, and decided to remove the first option as well to make it nice and even.

is this a feasible challenge? i will add more explanations and test data soon i think. adding my own client would probably be helpful

Answer 24

Code Golfed Rosetta Code Code Golfer

code-golf (any others? maybe metagolf, optimized-output and/or code-challenge)

Browsing examples on the Rosetta Code site, I can't help but think that all the code is just so long-winded, inefficient and ...well, readable. Something needs to be done.

Challenge

Choose a language, then write a function that takes the example source code, in the same language, for specific tasks on Rosetta Code and returns a golfed version of that code.

Winner is the person who can golf the example tasks the most. However, this is a code golf challenge so the length of your own source matters too.

Rules

1. Write a function in your chosen language that takes a string as input and returns a string as output (or equivalent - reading/writing to stdio or file, etc is also ok)
2. Input is the source code implementation, in your chosen language, of the following three specific tasks as shown on Rosetta Code (your function runs three times, once for each):
   • Quicksort
   • Happy numbers
   • Greatest common divisor
3. Output is a code golfed version of the input with identical functionality (again in the same language)
4. If there is more than one implementation of a task for a specific language, you must use the first listed
5. If your chosen language doesn't have an implementation for one of the tasks, then you need to add it yourself (following the Rosetta Code rules - don't go messing up their site just to get a better score here)
6. With the exception of the rule above, you may not, in any way, modify the content or order of examples on Rosetta Code
7. You must leave the logical flow of the algorithm mostly intact (eg. you can't simply replace the J quick sort code with /:~)

Scoring

Score for each individual task is calculated as the output character count as a percentage of the input character count. Implementation score for your own code is simply its character count. Total score for a submission is the sum of the three task scores, plus the implementation score.

Submission with the lowest score wins.

So, assuming your function is 100 chars long and running it against the test tasks gives you the output counts shown, your overall score would be calculated as follows:

 Task      | Input char count | Output char count | Score
-----------+------------------+-------------------+--------
 Quicksort |            600   |            400    |  67%
 Happy Nos |            400   |            200    |  50%
 GCD       |            200   |            150    |  75%
--------------------------------------------------+--------
 Implementation score:                            |  100
--------------------------------------------------+--------
 Overall score:                                   |  292

---

Things I'm not sure about...

Before I post this as a challenge, it would be good to get input on a few things:

• Will the "if your language doesn't have an implementation" rule cause problems, or can people be trusted to provide sensible implementations that follow the intent of Rosetta Code and don't simply artificially improve their score on the challenge? Is it better just to deny entries from languages which don't already have implementations?
• With scoring, obviously it's a balancing act, a really terse language will likely get a solid "implementation" score, but should be less able to improve the length of the examples, whereas a verbose language will be the opposite. So, the having too few "tasks" included in the challenge will benefit terse languages, and too many will benefit verbose languages. I want to find a middle ground, so does three tasks seem reasonable?
• Will someone just find an edge case language which has a really easily golf-able Rosetta example, that will make it unbeatable?

Answer 25

Distance between two words

You are given an input of two strings consisting entirely of letter characters. The "distance" between two such strings is the number of operations from the following list that it takes in order to transform one word into the other:

1. Adding a letter anywhere
2. Removing a letter anywhere
3. Changing a letter's case

Since your boss wants to avoid wear on the office keyboards as much as possible, you have to write a very short program to determine the distance between words so you can fix the typos.

Answer 26

Cross Validated

code-golf ascii-art

(This challenge is almost complete, but something doesn't feel quite right)

Continuing the theme of using site names as challenges...

Your task

Write a program or function that accepts a string, and prints out the location, size, and validity of each cross in the string.

Definitions

• Valid Cross- A cross where all four spokes of the cross are equal in length. The size of the cross is the number of segments of each cross.

Valid, size 0:

+

Valid, size 3:

   |
   |
   |
---+---
   |
   |
   |

• Invalid cross- A cross where one or more spoke is a different length. The size is the number of segments of the longest spoke.

Invalid, size 2:

 |
 |
-+--
 |

Invalid, size 6:

+------

Rules

• Each input will have one or more crosses.
• The program should print out the location of the center of each cross. The location is zero-indexed and measured in characters/lines from the top left.
• The size and validity, as defined above, of each cross should be printed out.
• Each test case must pass without printing to STDERR.
• Crosses will not overlap
• Your program can take input via a string (with line breaks), an array of strings (each representing a line), or a 2d array of characters.
• This is code-golf so shortest program, in bytes, wins

Test Cases

+ +-

(0,0) size 0, valid

(2,0) size 1, invalid

   |
   |     |
   |     |
---+---  |
   |     |
   |  ---+
   |

(3,3) size 3, valid

(9,5) size 4, invalid

(empty test case)

(must not crash or print to STDERR)

Answer 27

This question isn't fair.

I want you to tell me the chances of flipping an coin n times and ending up on tails.

Naturally this isn't a fair coin. In fact, it isn't even a standard unfair coin, where the chance of flipping tails is always p. This is a sticky coin, where the chance of the coin staying the same is p; the coin is fair at other times.

The coin starts off heads, so when n is 0 or p is 1 then the answer is always 0.

Your program or function should be capable of calculating the result to at least six significant digits.

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

Answer 28

"Optimize" a RegEx

code-golf

Introduction

Inspired by atrociously large regex's like

/[0-9A-Za-z!@#$%&*()_\-+={[}\]|\:;"'<,>.?\/\\~`]+[0-9A-Za-z!@#$%&*()_\-+={[}\]|\:;"'<,>.?\/\\~`]*/g

I propose a code-golf challenge to create a string representing an optimized and sorted regex from an input string of characters expected to be matched.

Rules

• only printable ASCII characters with code points 32 - 127 need to be supported:

 !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

The RegEx output string should:

• Group 3 or more consecutive code points in the input string together like begin-end
• Sort the characters and groups in order of ascending code point
• Escape the literal character - to \- to differentiate it from a range

The RegEx output string should not:

• Escape the characters !$()*+./=?[\]^{|}
• Support any RegEx escape sequences like \w, \d or \s

Examples

Input:
helloworld
Output:
dehlorw

Input:
fedcabXZYVWU
Output:
U-Za-f

Input:
q0`p[|iOf(oc61TSr4dVwQ8m;%YDAPM*a/2j&h~u}
Output:
%&(*/-2468;ADMO-QSTVY[`acdfh-jmo-ruw|-~

Just so people can see what the last one's pattern is, here are the ASCII indices:

37,38,40,42,47-50,52,54,56,59,65,68,77,79-81,83,84,86,89,91,96,97,99,100,102,104-106,109,111-114,117,119,124-126

Spoiler Alert

Example implementation in JavaScript ES6:

f=s=>[...s] // spread string into array
  .sort() // sort array by ASCII indices
  .map(
    c=>c.charCodeAt() // convert each one to ASCII index
  ).reduce( // reduce sorted indices
    (p,c)=>(
      ~p[0][0]+c? // if last index is not one less than current index
        p.unshift([c]): // then start new run with this index
        p[0].unshift(c) // else continue existing run
      ,p
    ),
    [[]] // start reduce with empty run
  ).map( // map array of runs
    a=>(
      (
        a=a.map( // map each run
          n=>( // convert index back to ASCII
            c=String.fromCharCode(n),
            c=='-'? // if '-'
              '\-': // then escape it
              c
          )
        ),
        a.length>2? // if run has more than 2 indices
          [a[0],'-',a.pop()]: // keep only the begin and end
          a // else keep whole run
      ).reverse().join`` // reverse and join run
    )
  ).reverse().join`` // reverse and join array

Answer 29

Exercise your kids

I want you to output the nth verse of this kid's exercise song:

Head, and shoulders, knees and toes, knees and toes,
Head, and shoulders, knees and toes, knees and toes
And eyes and ears and mouth and nose,
Head, and shoulders, knees and toes, knees and toes.

Each verse is the same as the previous except that all occurrences of one word is masked by replacing it with a dash (you can use a two-byte dash of your choice) wherever it appears in the verse. The words are replaced in order however the word "and" is never replaced, therefore the next verse should look like this:

—, and shoulders, knees and toes, knees and toes,
—, and shoulders, knees and toes, knees and toes
And eyes and ears and mouth and nose,
—, and shoulders, knees and toes, knees and toes.

Also, the last verse should look like this:

—, and —, — and —, — and —,
—, and —, — and —, — and —
And — and — and — and —,
—, and —, — and —, — and —.

Your answer should specify whether n will range from 0 to 8 or 1 to 9.

code-golf kolmogorov-complexity

Answer 30

Calculate the Average Squared Error

Given a line y = mx + b and a set of n points (x_i, y_i), find the average square error between the given line and each set of points.

Your goal is to create a function or program that given the values m, b, and the set of points (x_i, y_i), outputs the average square error according to the formula above.

Rules

• This is code-golf so the shortest solution wins.
• Builtins that compute this value are not allowed. This includes builtins that compute a result which is a scaled value of this.
• Floating-point inaccuracies will not be counted against you.

Test Cases

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