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

Count the ways to transform (2)

Your input is a matrix (2d array) of positive integers. For example:

\begin{matrix} 1 & 1 & 4 & 7\\ 1 & 3 & 5 & 6\\ 2 & 1 & 4 & 5 \\ \end{matrix}

A semi-continuous transformation of this matrix is a rearranging of elements that preserves immediate neighbors. For example, we can swap the \$2\$ in the bottom left, and the \$1\$ in the top left corner.

\begin{matrix} 2 & 1 & 4 & 7\\ 1 & 3 & 5 & 6\\ 1 & 1 & 4 & 5 \\ \end{matrix}

This is fine, because every number has the same neighborhood counts. That is, we can make a sorted list of numbers and their neighbors, and verify the they are the same:

\begin{matrix} \text{Number} & \text{Neighbors} \\ 1 & 1,1 \\ 1 & 1,2,3 \\ 1 & 1,3,4 \\ 1 & 2,3,4 \\ 2 & 1,1 \\ 3 & 1,1,1,5 \\ 4 & 1,5,7 \\ 4 & 1,5,5 \\ 5 & 3,4,4,6 \\ 6 & 5,5,7 \\ 7 & 4,6 \end{matrix}

Here is another example.

\begin{matrix} 2 & 1 & 1\\ 1 & 3 & 1\\ 1 & 1 & 4\\ \end{matrix}

Let's make a neighbor list. Note that we are gonna have duplicate entries (which is fine)

\begin{matrix} \text{Number} & \text{Neighbors} \\ 1 & 1,1 \\ 1 & 1,1 \\ 1 & 1,2,3 \\ 1 & 1,2,3 \\ 1 & 1,3,4 \\ 1 & 1,3,4 \\ 2 & 1,1 \\ 3 & 1,1,1,1 \\ 4 & 1,1 \\ \end{matrix}

Now, can we swap the top left \$2\$ and the bottom left \$1\$? It may look fine at first glance, but we must be careful! By swapping those two elements we would create a \$1\$ which has neighbors \$2,3,4\$, which didn't exist in the first input.

Just to demonstrate, here is the matrix after this non-semi-continuous transformation:

\begin{matrix} 1 & 1 & 1\\ 1 & 3 & 1\\ 2 & 1 & 4\\ \end{matrix}

And here is the neighbor list:

\begin{matrix} \text{Number} & \text{Neighbors} \\ 1 & 1,1 \\ 1 & 1,1 \\ 1 & 1,1,3 \\ 1 & 1,2,3 \\ 1 & 1,3,4 \\ 1 & 2,3,4 \\ 2 & 1,1 \\ 3 & 1,1,1,1 \\ 4 & 1,1 \\ \end{matrix}

Which is has changed after the transformation, ergo the transformation is non-semi-continuous (on this input).

To clarify, semi-continuity is a property of a transformation on some specific matrix.

Your code will take a matrix as input and output the number of (unique) semi-continuous transformations. Two transformations are different if the output is different. So for example swapping two identical numbers is the same as the identity transform (doing nothing).

Or in other words: Your code will take a matrix and return the number of matrices with those dimensions that have the same neighbor-list.

Answer 2

Trap the persistent hero in a maze

Last time a challenger tried to thwart your evil magical deeds, they got trapped in a maze that you created to be as small as possible, giving up only a few steps from the exit. Now there is another hero on the way. If it ain't broke, why fix it, so you ask the magic ball about the moves the hero will make in the maze. There are good news, and bad news.

The good news is that the hero's moves are still predictable. There is a list of moves, which determine how the hero moves in an intersection. The bad news is that the hero is persistent, never really giving up. What this means is that the list of moves repeats forever.

TODO Explanation of the move list and rules

Your task is to write a program that traps the hero in the maze. You may assume that the input has a solution.

Answer 3

Count count count.. code-golf

Posted

Answer 4

Alphabet Polygon

Intro

Given a number of sides \$a\$ and a side length \$b\$, generate an \$a\$-sided polygon with side length \$b\$. The fill value will be the alphabet going clockwise. If there are not enough letters, wrap around.

Test cases

3 4

     A
    H B
   I   C
  G F E D


4 4

ABCD
L  E
K  F
JIHG
```

Answer 5

Shuffle up a list

Given two lists \$A\$ and \$B\$, with no repeats in elements and so that the elements of \$B\$ are identical to the elements of \$A\$ except for the order they are in, we say \$B\$ is an \$n\$-well-shuffled list of \$A\$ (where \$n\$ is a nonnegative integer) if:

• For any \$(a_1, a_2, \cdots, a_n) \in A^n\$, \$a_1\$'s position in \$A\$ is \$\neq\$ its position in \$B\$, \$a_2\$'s position in \$A\$ is \$\neq\$ its position in \$B\$, ... and \$a_n\$'s position in \$A\$ is \$\neq\$ its position in \$B\$
• For any \$(a_1, a_2, \cdots, a_n) \in A^n\$, if \$a_i\$ precedes \$a_j\$ for some \$(i, j) \in [1, n]^2\$ in \$A\$, then \$a_i\$ follows \$a_j\$ in \$B\$

Your task is to take two nonnegative integers \$m, n\$ as input and return how-many \$n\$-well-shuffled lists of lists of length \$m\$ there are.

Answer 6

Is this a Hamiltonian cycle?

Answer 7

Climbing the Bookshelf code-golf

Climbing the Bookshelf

Answer 8

Is it an action?

abstract-algebra decision-problem code-golf

---

Today, you will solve an abstract algebra challenge.

Consider a set \$G\$, which, to simplify things, is a finite subset of \$\mathbb{Z}\$ containing \$0\$. It has a binary operation \$*\$, which for our example will be \$+\$, but your program should be able to handle any binary operation. If \$G\$ is closed under \$*\$, i.e. \$g * g' \in G \forall g, g' \in G\$, there is associativity with regard to \$*\$, there is a unique element in \$G\$, which we will note as \$1_G\$, such that \$1_G * g = g * 1_G = g \forall g \in G\$, and there exists a unique \$g^{-1} \in G \forall g \in G\$ such that \$ g * g^{-1} = g^{-1} * g = 1_G \$, then \$G\$ is a group.

Consider a set \$X\$, which is also a finite subset of \$\mathbb{Z}\$. Then \$\circ: G \times X \to X\$, where \$G\$ is a group, is an action if:

• \$1_G \circ x = x \forall x \in X\$, and
• \$g \circ (g' \circ x) = (g * g') \circ x \forall g, g' \in G, x \in X\$ (associativity).

Challenge

Your task is to write a program or function which takes in the following:

• \$G\$, a finite subset of \$\mathbb{Z}\$ that includes \$0\$;
• \$X\$, also a finite subset of \$\mathbb{Z}\$, but not necessarily the same as \$G\$;
• a binary operation \$*\$ that operates within \$G\$ and that makes \$(G, *)\$ a group, which can be taken in any reasonable manner you would like, such as taking it as a function with two parameters, and
• an "application" \$\circ\$ from \$G \times X\$ to \$X\$, which can be taken in any reasonable manner you would like.

For the purposes of this challenge, \$1_G\$ is always \$0\$.

This program should then output true if \$\circ\$ is an action and false if not. You may use any two distinct values for true and false.

The shortest code, measured in bytes, wins.

Test cases.

\$G = \{0, 1, 2\}\$

\$X = \{1, 2, 3\}\$

\$*\$ defined by \$g * g' = (g + g') mod 3\$

\$\circ\$ defined by \$g \circ x = g + x\$

Output: false because:

• \$1_G\$ is 0;
• then \$1_G \circ x = 0 \circ x = 0 + x = x\$;
• but \$(1 * 2) \circ 2 = 0 \circ 2 = 2 \neq 1 + (2 + 2) mod 3 = 1 + (2 \circ 2) = 1 \circ (2 \circ 2)\$, thus \$\circ\$ is not associative.

\$G = \{0, 1, 2\}\$

\$X = \{0, 1, 2\}\$

\$*\$ defined by \$g * g' = (g + g') mod 3\$

\$\circ\$ defined by \$g \circ x = (g + x) mod 3\$

Output: true because:

• \$1_G\$ is 0;
• then \$1_G \circ x = 0 \circ x = (0 + x) mod 3 = x mod 3 = x\$ (because \$x < 3\$);
• and \$\circ\$ is associative (proof not provided)

Answer 9

Quicksand

In this fastest-code challenge, you take a positive integer as input, which represents the height of a sand pile, located at (0,0) on an infinite square grid. For example, if our input is 123, the sand grid looks initially like this:

\$\begin{matrix} 0 & 0 & 0 \\ 0 &123& 0 \\ 0 & 0 & 0 \end{matrix}\$

Now, piles of sand are unstable, so they topple if their height is 4 or greater. When sand piles topple, they send sand equally in all four directions, but due to the quantum nature of sand, the amount sent is an integer. Or in other words, if there is a pile of height n, it sends sand as follows:

\$\begin{matrix} 0 & \lfloor\frac{n}{4}\rfloor & 0 \\ \lfloor\frac{n}{4}\rfloor & n\mod 4 & \lfloor\frac{n}{4}\rfloor \\ 0 & \lfloor\frac{n}{4}\rfloor & 0 \end{matrix}\$

This means that sandpiles evolve step by step. For example, if we have this initial position, here's how the sandpiles evolve.

\$\begin{matrix} 0 & 0 & 0 & 0 \\ 0 & 0 & 6 & 0 \\ 0 & 2 & 7 & 0 \\ 0 & 0 & 0 & 0 \end{matrix}\$

\$\begin{matrix} 0 & 0 & 1 & 0 \\ 0 & 1 & 3 & 1 \\ 0 & 3 & 4 & 1 \\ 0 & 0 & 1 & 0 \end{matrix}\$

\$\begin{matrix} 0 & 0 & 1 & 0 \\ 0 & 1 & 4 & 1 \\ 0 & 4 & 0 & 2 \\ 0 & 0 & 2 & 0 \end{matrix}\$

\$\begin{matrix} 0 & 0 & 2 & 0 \\ 0 & 3 & 0 & 2 \\ 1 & 0 & 2 & 2 \\ 0 & 1 & 2 & 0 \end{matrix}\$

Now, since all the sandpiles have less than 4 sand, this sand grid is stable.

Rules

Your task is to take an positive integer \$i\$ as input, and output the eventually stable grid that the following initial position evolves to:

Todo add cool fractals

\$\begin{matrix} 0 & 0 & 0 \\ 0 & i & 0 \\ 0 & 0 & 0 \end{matrix}\$

(Note that the grid is still infinitely big)

The output format should be the following: "width;data", where width is an odd number representing the width a square that bounds the eventually stable arrangement (width doesn't have to be the smallest possible). Next is the raw data, which is just the square section of the grid flattened, and the numbers are represented with digits "0123"

Answer 10

Word Guess KOTH

Inspired by Wordle and Evil Wordle.

A King of the Hill game where you must write a bot which acts as both Guesser and Judge of a word guessing game. Each bot will play a match against all the other bots. Each match will consist of 10 rounds alternating between judge and guesser. A bot's score for the match is the number of guesses the opponent made minus the number of guesses it made. Higher is better. Bot with the highest average [or total?] score is KOTH.

The game is as follows:

1. The Judge and Guesser are both provided with the same dictionary of N letter words.
2. The Judge selects an answer from the dictionary.
3. The Guesser makes a guess. The candidate word must be contained in the dictionary.
4. The Judge is given the guess, and provides a score according to the following rules.

• The score is a string of N characters from the set ['G','O','B'], corresponding to the guessed letters

  • A 'G' indicates that the guessed letter is correct for that position. Great
  • A 'O' signifies that the guessed letter is in that answer but not that position. Out-of-place.
  • A 'B' indicates that the guessed letter is not in the answer. Bad.

• If a letter appears in the guess more than once, there will never be more non-'B' results than instances of that letter in the answer.

  • for example if the answer is 'ruler' and the guess is 'belle', the score will be 'BOGBB'.

4. Steps 2 and 3 continue until the score is all 'G's.
5. The the number of guesses is added to the Judge's score and subtracted from the Guesser's.

• Note that the judge is free to modify the answer after each guess, as long as the new answer is consistent with all the previous guesses.

An example scoring function in Python is:

def count_score(truth, trial):
    score = [None]*len(truth)
    allow = truth
    for index,value in enumerate(trial):
        if truth[index]==value:
            score[index]='G'
            allow=allow.replace(value,'',1)
        for index,value in enumerate(trial):
        if not score[index]:
            if value in allow:
                score[index]='O'
                allow=allow.replace(value,'',1)
            else:
                score[index]='B'
    return ''.join(score)

Entries must provide a bot command that can be called from the command line and prints the required outputs to stdout, separated by newlines.

For all the use cases below, codex is a filepath to a dictionary of legal words, and token is a string used by a bot to maintain state. It must not be empty. The token generated in any round is passed back to the same bot in the following round. The opponent bot will never see your token. Tokens are not retained from one round to the next.

arguments --> results

codex "judge" --> token Judge initialization. Returns a token.

codex "judge" token trial --> token score Judge will score the trial word. score is constructed according to the rules above.

codex "guess" --> token trial Guesser makes initial trial guess.

codex "guess" token score - token trial Guesser gets score from previous guess. Returns new trial guess.

Example Bot:

import random,sys,re

def begin_offer(codex):
    words = [l.strip() for l in open(codex)]
    return [random.choice(words)]

def score_trial(token, trial):
    return token, count_score(token,trial)

def first_guess(codex):
    words = sorted([l.strip() for l in open(codex)])
    guess = words[0]
    return (guess, guess)

def later_guess(codex, prior, score):
    words = sorted([l.strip() for l in open(codex)])
    index = words.index(prior)
                  
    for place,value in enumerate(score):
        if value != 'G':
            while words[index][place]==prior[place]:
                index+=1
            break
    guess = words[index]
    return guess,guess


if __name__ == "__main__":
    codex,style,*extra = sys.argv[1:]
    if style == 'judge':
        if not extra:
            result = begin_offer(codex)
        else:
            result = score_trial(*extra)
    elif style == 'guess':
        if not extra:
            result = first_guess(codex)
        else:
            result = later_guess(codex,*extra)

    print("\n".join(result))

Match Runner (in progress)

import sys,subprocess
def reply_split(reply):
    return [bites.decode('ascii').strip() for bites in reply.split()]

if __name__ == "__main__":
    judge,guess = sys.argv[1:]

    reply = subprocess.check_output([judge, "words.txt", "judge"])
    judge_token,*trash = reply_split(reply)

    reply = subprocess.check_output([guess, "words.txt", "guess"])
    guess_token,trial = reply_split(reply)

    for round in range(10):

        print(trial)
    
        reply = subprocess.check_output([judge, "words.txt", "judge", judge_token, trial])
        judge_token,score,*trash = reply_split(reply)

        print(score, "\n")
        if score == 'GGGGG':
            print("{} guessed {}'s word in {} rounds".format(guess, judge, round+1))
            break
        
        reply = subprocess.check_output([guess, "words.txt", "guess", guess_token, score])
        guess_token,trial,*trash = reply_split(reply)

    print(round+1)

Answer 11

Bracket Depth List

Answer 12

Decompress a ragged list

Answer 13

Very simple auto battler

There are two players. Each player has a team of between 0 and 5 members. Each member has two relevant statistics: an attack score and a health score. These range from 1 to 50.

Until at least one team runs out of members, you need to battle the lead member of each team against each other. (You can decide whether this is the first or last member of the team.) The two attacks are simultaneous, so it's possible that both members can defeat each other. Each attack reduces the foe's health by the user's attack. Once a team member's health is reduced to zero (or less) then it faints and takes no part in the rest of the battle.

If both teams simultaneously run out of unfainted members then the result is a draw otherwise the team that still has unfainted members wins.

Your task, given two teams in a reasonable format, e.g. list of tuples of (health, attack), is to write a program or function that outputs which (if any) team will win, using one of three specific values of your choice, e.g. -1, 0 and 1, or A, B and D. (Please describe the mapping of values in your answer.)

This is code-golf, so the shortest program or function that breaks no standard loopholes wins!

Sample team generator and battler

Answer 14

Triangle Tripler

Answer 15

Interpret Subleq code

code-golf parsing

Background

Subleq is a language that has only one 3 argument instruction. The instruction has three operands A B C. When executed it subtracts the contents in address A from address B; stores the result in address B; if the result is less than or equal to 0 it goes to address C. -1 in a position has special meaning. -1 in A will read the ASCII value of then next character of input into B; if no more input then goto 'C'. -1 in B will send the ASCII character in A to output. -1 in C will exit the program instead of going to an address.

Task

Given input and Subleq code, output the results from running the Subleq code.

An interpreter built in Excel is here.

Rules

• You may use any standard I/O method
• Standard loopholes are forbidden
• This is code-golf, so the shortest code in bytes wins

Test Cases

For the test cases below, any input to the Subleq is before the '/', code is after. Code is represented by decimal numbers.

Hello, World!

Input=>
/
12 -1 13
1 0 6
3 2 -1
4 4 0
72 101 108 108 111 42 32 87 111 114 108 100 33
Output
Hello, World!

!I!n!s!e!r!t! !i!n!b!e!t!w!e!e!n!

Input->
1 2 3 4 5 6/
2 -1 33
-1 8 -1
8 -1 0
8 8 
Output
!1! !2! !3! !4! !5! !6!

Meta

• What am I leaving out?
• Is there a better way of handling the input to the Subleq code?
• Does it need more/better examples?

Answer 16

Generate all groupings

Answer 17

Bigger regex?

Answer 18

Knights Jam | Chess

Answer 19

Factorials of primes decomposition

Answer 20

Play 1D minesweeper

Answer 21

Page Selector

Answer 22

Can the Tune be Played?

I changed the question slightly from when it was posted on the Sandbox.

Answer 23

The Nineteenth Bakery

Answer 24

Reveal all clues of Black Box

Black Box is a board game, Your task is to reveal all clues.

What is black box

Black box is a board game with hidden atoms, Your task is given input, All atoms, reveal all clues.

I/O

Input

The atoms can be any 1-char that is not newline (Used for separator) Like this.

O....
...O.
..O..
.....
....O

Output

When the code reveals all clues (See Below) the output of The given input above can be:

 HRHH1
H     1
R     H
H     H
2     R
H     H
 H2HRH

or

[["H", "R", "H", "H", "1"], ["1", "H", "H", "R", "H"], ["H", "R", "H", "2", "H"], ["H", "2", "H", "R", "H"]]

Ignore the number, This doesn't mean anything, the number can be non-unique

Task

Hit

Atoms interact with rays in three ways. A direct impact on an atom by a ray is a "hit".

.........
.........
.O.....O.
.........
.........
...O.....H 1
.........
.......O.

Thus, ray 1 fired into the box configuration at left strikes an atom directly, generating a "hit", designated by an "H". A ray which hits an atom does not emerge from the box.

Deflection

The interaction resulting from a ray which does not actually hit an atom, but which passes directly to one side of the ball is called a "deflection". The angle of deflection for this ray/atom interaction is 90 degrees. Ray 2 is deflected by the atom at left, exiting the box as shown.

    2
.........
.........
.O.....O.
.........
.........2
...O.....
.........
.......O.

Reflection

The final type of interaction of a ray with an atom is a "reflection", designated by an "R". This occurs in two circumstances. If an atom is at the edge of the grid, any ray which is aimed into the grid directly beside it causes a reflection.

.........
.........
.O.....O.
.........
.........
...O.....
.........
.......O.
      RHR
      354

Rays 3 and 4 at left would each generate a reflection, due to the atom at the edge. Ray 5 would be a hit on the atom.

Double deflection

The other circumstance leading to a reflection is when two deflections cancel out. In the grid at left, ray 6 results in a reflection due to its interaction with the atoms in the grid.

   6

   R
.....
..O.O
.....
.....
.....

Detour

Rays that don't result in hits or reflections are called "detours". These may be single or multiple deflections, or misses. A detour has an entry and an exit location, while hits and reflections only have an entry location for a hit, and a single entry/exit location for a reflection.

  8   8  
.........
.........
.O.....O.
.........9
.........
...O.....
.........9
.......O.

Of course, more complex situations result when these behaviors interact. Ray 8 results in two deflections, as does ray 9.

Some rays travel a twisted course, like ray 1 at left.

 .........
 .........
 .O.....O.
 .........
1.........
 ...O.....
 .........
 .......O.
     1

Notice that this complex set of five deflections above looks exactly like a single deflection, as shown by ray 2 at left. Things are not always as simple as they seem within a black box.

 .........
 .........
 .........
 .....O...
1.........
 .........
 .........
 .........
     1

Reflections and hits can be more complex, too. Ray 2 gets deflected by the first atom, reflected by the next two atoms and again deflected by the original atom, yielding a reflection.

.O...
.....R 2
.....
.O.O.
.....

Ray 3 below gets deflected by the first atom, then by the second atom, and then hits the third atom, yielding a hit.

   ...O.
   O....
   .....
3 H.....
   ...O.

Test cases

O....
...O.
..O..
.....
....O
->
 HRHH1
H     1
R     H
H     H
2     R
H     H
 H2HRH

O
->
 H
H H
 H

OOO
O O
OOO
->
 HHH
H   H
H   H
H   H
 HHH

..O..
O...O
..O..
->
 HRHRH
R     R
H     H
R     R
 HRHRH

...
...
...
->
 123
4   4
5   5
6   6
 123

....
O...
...O
....
->
 H1HH
R    1
H    R
R    H
2    R
 HH2H

Meta:

• Any feedback?

Answer 25

Negative of an ASCII photo

Answer 26

Overlay the Ukrainian Flag

A pseudo-sequel to this challenge.

The Challenge

As of the posting of this challenge, my PFP has a blue-and-yellow overlay in support of Ukraine. Your task is to, given the path to an input image, overlay a similar image on top.

Here is the flag:

• The flag is divided horizontally across the middle into two equally sized stripes.
• Stripe colors: (0, 87, 183) or #0057B7 (blue, top) and (255, 215, 0) or #FFD700 (yellow, bottom).
• You must, given the path to an image as input, overlay two semi-transparent rectangles of those colors onto it. The rectangles must each take up half the vertical area of the image, and be as wide as the image.
• The rectangles must have 70% opacity.
• Colors must be exact if possible, otherwise use the closest available blue and yellow.
• The image can be saved to a file or piped raw to STDOUT in any common image file format, or it can be displayed in a window.
• If you're saving to a file, you may either overwrite the old image or create a new one.
• Built-in flag images, flag-drawing libraries, or horrendously upscaling the Ukrainian flag emoji are prohibited.

Answer 27

Overlay Two Images

This challenge is as simple as it gets: Just take two images as input (in any reasonable format) and overlay the first atop the second.

• The overlay must have 70% opacity (if possible, if not use the closest available analog), or in other words, multiply the overlay's pixel values by 0.3 and the base by 0.7.
• The overlay must be centered over the base image.
• If the overlay is bigger, it must be cropped to fit within the base.
• If the base image is bigger, the overlay does not need to be enlarged.

Answer 28

Optimally break a string into substrings

code-golf string optimization

Answer 29

Simplified Piet Interpreter

Answer 30

Draw the Norwegian flag