# Sandbox for Proposed Challenges

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.

Sandbox FAQ

## Posting

Write your challenge just as you would when actually posting it, though you can optionally add a title at the top. 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, and replace the post here with a link to the challenge and delete the sandbox post.

## Discussion

The purpose of the sandbox is to give and receive feedback on posts. If you want to, feel free to give feedback to any posts you see here. Important things to comment about can include:

• Parts of the challenge you found unclear
• Problems that could make the challenge uninteresting or unfit for the site

You don't need any qualifications to review sandbox posts. The target audience of most of these challenges is code golfers like you, so anything you find unclear will probably be unclear to others.

If you think one of your posts needs more feedback, but it's been ignored, you can ask for feedback in The Nineteenth Byte. It's not only allowed, but highly recommended!

It is recommended to leave your posts in the sandbox for at least several days, and until it receives upvotes and any feedback has been addressed.

## Other

Search the sandbox / Browse your pending proposals

The sandbox works best if you sort posts by active.

To add an inline tag to a proposal use shortcut link syntax with a prefix: [tag:king-of-the-hill]. To search for posts with a certain tag, include the name in quotes: "king-of-the-hill".

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# Count strictly overlapping substrings code-golfstringcountingsubsequence

Posted

• Is it correct that 1 is never a valid result?
Jan 28 at 17:04
• @Adám yes; do you think I should add that? Jan 28 at 17:04
• Probably a good idea.
Jan 28 at 17:05
• You need test cases with longer bs that can overlap themselves in multiple ways.
Jan 28 at 17:27

# Pad a jagged array to be square code-golfarray-manipulation

Posted

• Add a test case for pad value -1 or something like that. Feb 12 at 14:55
• Can any dimension of the input array be 0? [please review other sandbox posts] Feb 12 at 14:56
• Also add a test case with an array consisting of only fill values. Feb 12 at 14:58
• @user202729 what do you mean by "[please review other sandbox posts]"? I don't see the need for a test case with pad value -1, because the type of the elements in the array is answer-defined. I'll clarify the other two though Feb 12 at 16:22
• I suggest that you specify more clearly what input formats are allowed, that is, what counts as an "array". For example, is it acceptable to take lines of text with space as separator within each line? Or use two types of brackets, such as {[1, 5, 3], [4, 5], [1, 2, 2, 5]}? Feb 12 at 18:31
• @LuisMendo input should be taken in your language's natural representation of nested arrays. If it doesn't have a builtin array representation, then take it in some kind of text representation like I mentioned in the rules section Feb 12 at 18:49
• The problem with saying "natural representation" is that a language may have more than one way of representing nested tuples. That said, I think what you have in the question is alright - perhaps to clarify what Luis is talking about you could add: "input can be any unambiguous representation of a jagged array"? I think what Luis may be getting at is that there could be a problem with e.g. a Python array contains meta-information (the length) while a C array wouldn't, but usually I think that is left out. Feb 12 at 19:26
• To explain my point better: MATLAB (or MATL) can use curly braces for arbitrary arrays, and square brackets for rectangular arrays. So either {{1, 5, 3}, {4, 5}, {1, 2, 2, 5}} or {[1, 5, 3], [4, 5], [1, 2, 2, 5]} could be used as input. The latter is probably better to reduce code length. Can we just choose the most convenient one? What is the limit where choosing a convenient format counts as "pre-processing" the input and is not allowed? All this is language-dependent, but some general specification would be needed Feb 12 at 19:33
• @pxeger Something that I tend to add to my sandbox review comments recently, hoping to reduce the problem of the sandbox posts not being reviewed enough. Feb 13 at 2:37
• @LuisMendo You can probably choose any convenient one (I think that's the common consensus?) Feb 13 at 2:38
• The "-1" thing is just to make people notice that the value to be padded is an input rather than hard coded by the code. Feb 13 at 2:46

## Snail word

Very similar to other challenges

# Draw four colorful quarter circles

The challenge is to reproduce this image in your favorite language:

• Your image must be at least 400 by 400 pixels.
• The fill colors don't need to be the same as in the image but they must be different from each other.
• You must include the outlines but they can be any visible thickness you choose.
• The quarters should be at the same orientation as in the image.
• Your image must have four quarter circles aligned as in the image which each touch the edge of the circle at a point.
• Your code must take input which specifies the location, in pixels, of the point where the quarter-circles meet; you can take this input in any reasonable format, but the units must be pixels (no relative units, such as a fraction of the width/height of the image). You can assume these inputs are always within the bounds of the outer circle. You can also assume that the inputs are such that all four quarter circles can be drawn within the circle.

Here is some LaTeX code as an example:

\documentclass[tikz,margin=3mm]{standalone}
\usetikzlibrary{calc,through}

\usetikzlibrary{intersections}

\begin{document}
\begin{tikzpicture}[inner sep=0pt, outer sep=0pt]

\coordinate (point) at (-0.1,0.4);

\draw [name path=mycirc] (0,0) circle [radius=1];
\path [name path=di-1] (point) -- ++(-2,2);
\path [name path=di-2] (point) -- ++(-2,-2);
\path [name path=di-3] (point) -- ++(2,-2);
\path [name path=di-4] (point) -- ++(2,2);

\foreach \col [count=\i] in {yellow,red,blue,brown}{

\fill [red, name intersections={of=mycirc and di-\i}] (intersection-1) circle [radius=0.05] node (inter-\i) {};

\fill[\col,draw=black,rotate around={(\i+3)*90:(point)}] (point)
let \p1 = ($(point) - (inter-\i)$) in
arc [start angle=0, end angle=90, radius={0.707*veclen(\x1,\y1)}]
-- +(270:{0.707*veclen(\x1,\y1)}) -- cycle ;
}

\end{tikzpicture}
\end{document}


[I would love help on how to improve this challenge.]

• Describing the exact ratios of the shapes would be helpful in drawing them
– user
Mar 5 at 15:34
• Those are quarter-circles, not semicircles Mar 5 at 15:46
• Might be more interesting if the center of the shape (where the petals meet) was an input Mar 5 at 15:54
• @pxeger ahem.. thanks :) Mar 5 at 15:57
• @ZaelinGoodman Could you say exactly how that could be specified? Mar 5 at 15:59
• @Anush Since the image is 300 x 300 pixels, you could say something like you must take input which specifies the location, in pixels, of the point where the quarter-circles meet; you can take this input in any reasonable format, but the units must be pixels (no relative units, such as a fraction of the width/height of the image). You can assume these inputs are always within the bounds of the outer circle. Mar 5 at 16:03
• "Your image must be at least 400 by 400 pixels" what about vector graphics? If some one choice to output the image with vector graphics format. How to define its width and height?
– tsh
Mar 9 at 5:51

# Gray code... Gray code?

Your task is to print (in an easily readable and consistent format) the binary representations of the numbers 0-255 in some order such that only one bit is altered between two consecutive numbers.

Each successive byte of the source code after the first can only change one bit from the previous byte.

### Other Information

Example valid code (in utf-8): q1!#c. Here, q (01110001) and 1 (00110001) are different in only one bit, and so on

Example invalid codes (in utf-8): Q1!, "!"

Example valid outputs (seperated by an empty line):

10101010 10101011 11101011 ... 01010101

[10, 11, 1011, 1111, 1110, ...]

10
0
1
11
111
...


Example invalid outputs (seperated by an empty line):

0000000100000011000000100000000000000100...

0
01
10
11
100
...

0 1 ... 100000000 110000000 ... 11111111

00 01 11 10 0100 0101 ...

0 1 3 2 5 6 ...


Notes:

• A character can be stored as two bytes, but the bytes must differ by only one bit
• If your interpreter ignores a character (like Whitespace ignores almost all characters) it cannot be used
• Is printing 1 3 2 6 7 5 4 and onwards ok? Feb 28 at 4:36
• What does "some form of gray code" mean exactly? / Clarify that the restriction part applies to the source code of the program. Feb 28 at 6:49
• I'll change it to binary gray code to avoid confusion. Feb 28 at 15:55
• You should describe what the gray code is to avoid ambiguities. Feb 28 at 21:49
• Do you think this challenge is too hard? Mar 2 at 15:01
• Is it okay if the output is printed in decimal instead of binary? Mar 3 at 13:20
• Perhaps add "addition of leading zeroes doesn't count as a change" and some examples to illustrate/example valid output (just for challenge accessibility, this is implied from the definition (and the Wikipedia page)) Mar 3 at 13:21
• Would be hard for practical languages, but for everything-are-valid languages it should not be a problem. Good challenge idea. Mar 3 at 13:22
• Does the last statement means "Your program should not work by removing any single bytes", or "Any subsequence of your program should not work."?
– tsh
Mar 16 at 11:43
• @tsh neither. It means that you can't use a character if it is completely skipped over by the interpreter. For example, in the python code "if len('abc') < 4: print('Hello, World')" the "c" can still be used because it is not skipped over by the interpreter. Mar 18 at 17:29

# Subarrays With At Least N Distinct Integers

• I don't get it. From 1,2,2,3 you can make 3 subsequences of 2 integers: 12; 22; 23. And the middle one is not made of different integers. So how it comes that "the number of contiguous subsequences that contain at least N distinct integers" is 5 in this case? Mar 7 at 11:55
• @Sheik 1,2, 1,2,2, 2,2,3, 2,3, 1,2,2,3 are the subsequences that contain at least 2 distinct integers. In my opinion, there should be a column in the table of test-cases that contains these sub-sequences for clarity. Mar 7 at 17:40
• @Hyperbole thank you very much. It wasn't that hard to get but, I don't know, English is not my language. Anyway if not on the test cases, they should be at least in an example before the tests. Mar 7 at 18:24
• @Hyperbole I appreciate the feedback. I updated the post with the example. Mar 7 at 18:57
• @SheikYerbouti I have updated the post with the example. Mar 7 at 18:57

# Tri tri tribonacci

Tribonacci from Wikipedia:

The tribonacci numbers are like the Fibonacci numbers, but instead of starting with two predetermined terms, the sequence starts with three predetermined terms and each term afterwards is the sum of the preceding three terms.

## The challenge

Given three arrays of three integers, for each array:

1. Find the generator G (the first non-negative integer) of the sequence to which the three numbers belong
2. Then find the G-th element of the sequence (zero-indexed*)

The three integers found are indeed part of a tribonacci sequence, output the G-th element of that sequence.

*The sequences are zero-indexed because G may be 0 and in that case you have to find the 0th element of the sequence.

## Example

Given the input

[[5, 11, 20], [1, 2, 3], [23, 39, 67]]


5 11 20 are part of the sequnce 2 4 5 11 20, which starts with 2, so we take the 2nd element of the sequence: 5

1 2 3 are part of 0 1 0 1 2 3, so we take 0

23 39 67 are part of the sequence 7 11 5 23 39 67 129 235 so we take 235

Now 5 0 235 are part of the sequence 230 5 0 235 so the output is the 230th element of that sequence:

174892031986606286607812889236621806383715371411020300455075910


## Input / output

You can take the input as you prefer: an array of three arrays, three arrays, an object, a string, etc.

You are not required to handle integers larger than those implemented by your chosen language, I will post plenty of test cases with smaller output after I make a program for the challenge.

This is , everyone wins.

# Meta

• Are you sure you meant to put This is [tag:code-golf], everyone wins.? That's not code golf :p Mar 8 at 23:55
• Looks fine to me, except for the "zero-indexed" part. 0-indexing and 1-indexing are usually equally allowed. (Also, people might complain about "why not just make it two challenges, one for finding the generator and one for n-th tribonacci") Mar 9 at 0:00
• @RedwolfPrograms we keep the truth in the sandbox, I will put "the shortest wins" in the challenge Mar 9 at 0:00
• @Bubbler the zero-indexing is because the sequence may start with 0, and in that case you have to find the 0th element of the sequence. About splitting the challenge, I didn't check but it's possible that one or both of the parts already exist. Mar 9 at 0:03
• @SheikYerbouti That makes sense. Then it would be better to include the justification of why it should be 0-indexed in the post. Mar 9 at 0:07
• @Bubbler I added a note to justify the restriction, thank you for the feedback! Mar 9 at 0:15
• Maybe "This is code golf, so shortest code wins, but who's counting?" instead of "everyone wins"? Mar 15 at 15:47

# Background

Let $$\a\$$ $$\\in \mathbb{N}\$$, $$\b\$$ $$\\in \mathbb{N}\$$, $$\c\$$ $$\\in \mathbb{N}\$$ and $$\S\$$ be some subset of $$\\{i:1\leq i\leq a\}\$$.

Consider $$\X(a ,b, c, S)\$$: The number of integer partitions of $$\a\$$ into $$\b\$$ many parts, where each of the parts are co-prime to $$\c\$$ and no part is contained within $$\S\$$.

Formally, for $$\b=2\$$

$$X(a ,2, c, S) = |\{(x, y): x + y = a,\ gcd(c, x) = gcd(c, y) = 1, x \notin S, y \notin S,\ x \leq\ y\}|$$

# Challenge

Codegolf, standard rules apply. Write code to calculate the function $$\X(a ,b, c, S)\$$ above.

Inputs:

• $$\a\$$, an integer. Your function does not need to be correct for $$\a \le 2\$$.

• $$\b\$$, an integer. Your function does not need to be correct for $$\b \le 1\$$.

• $$\c\$$, an integer.

• $$\S\$$, can be any set of integers between $$\1\$$ and $$\a\$$ (inclusive). The elements of $$\S\$$ are unique.

# Test-cases

Below test cases are written in the following format: $$\a, b, c, S =\$$ Answer

3, 2, 2, {} = 0
4, 2, 2, {} = 1
4, 2, 3, {2} = 0
7, 3, 5, {} = 3
7, 3, 2, {5} = 1
11, 3, 1, {} = 10
11, 3, 2, {} = 4
11, 3, 3, {5, 7} = 1


# BONUS

Brownie points for anyone who can do either of the following:

1. Disprove the following recursive relationship.
2. Extend the following recursive relationship (for higher values of $$\b\$$), and/or write code utilising it.

Recursive formula for $$\b = 3\$$ (Might be incorrect):

$$X(a ,3, c, S) = \sum_{i=1}^{i=\lfloor\frac{a}{2}\rfloor} {X(a - i, 2, c, T_i)}$$

With

$$T_0 = S$$

and,

$$T_i = T_{i-1}\cup\{i - 1, a + 1 - i\},\ for\ i \geq 1$$

# Questions for sandbox

Is this challenge good to go?

• you can add tags here via [tag:<tagname>]. Feb 27 at 8:37
• @Razetime , sorry total noob here. In the comment section? or do I edit the post and add the [tag:<tagname>] at the end? Feb 27 at 9:30
• in the post. Add it near the title, like in the other posts. Feb 27 at 9:55
• About test cases. It looks like that this challenge doesn't have too many test cases, don't need a lot. Feb 27 at 12:15
• I think the info about integer types makes the question harder to read (they all have default rules), so I removed it. Feb 27 at 12:15
• The tag doesn't matter too much, as long as there's a code golf tag. // Usually people don't like time limits, but if you insist there's either "solutions must have time complexity that does not exceed (something)" or "you must be able to run the program to completion with the following test cases" or "the program must finish on my machine in X seconds" (requires you running the programs) [please review other sandbox posts] Feb 27 at 12:17
• @user202729 Thanks for the edits. Yes I suppose I'm not interested in any time constraints. Rather just interested to see the solutions people can come up with. Yes I will need to make some test cases, will add them when I get a chance. Feb 27 at 13:01

# Decompress an integer, Jelly style

• Algorithm description looks good. Requiring to handle inputs up to $2^{64}-1$ sounds unfair to the languages that do not support that large integers though. I'd prefer something in the line of the 5th bullet under the Rules on this challenge. Mar 25 at 0:09

# Unique languages

As we found out before, each of the 680 languages on Try it online! has a "TIO uniqueness", defined as the length of the shortest substring that appeared in the language's name and no others'.

This time, we're going to make it more general. Given a list of strings S and a target T, output the length of the shortest substring of T that is not in any other element of S. You may choose whether T is part of S or not. The elements of S will always be unique. All elements of S, and T, will only contain lowercase letters (abcdefghijklmnopqrstuvwxyz). You may also take input as uppercase if you wish.

Your score will be calculated as code length × TIO uniqueness, where code length is measured in bytes and TIO uniqueness is the TIO uniqueness as specified here. If a language has an undefined TIO uniqueness, it cannot compete in this challenge.

The answer with the lowest score wins.

# Check B-powersmoothness - posted

• Can you link to the wiki article please. Mar 29 at 8:57

# Battery charging tracker

If there are any better titles please post them in the comments

If any more tags might be appropriate, please post them in the comments

The task here is to create a program which can output a battery's percentage at all times. It will be given input in the form of an array of "indications". These dictate when to plug and unplug the charger.

If this sounds confusing, let us take this sample input:

[[12, 23, 34], [15, 28, 67]]


Note: you can take input in the form of a list of strings or a single string if you would like.

The first array indicates the number of seconds to wait before unplugging the charger, and the second one indicates the number of seconds to wait before plugging in the charger. There will never be two coinciding values in one of the arrays or between the arrays. So [[11, 22, 33], [15, 22, 34]] is not valid input and neither is [[1, 2, 3, 3, 6], [15]]. Both arrays are guaranteed to have at least one value in them. Also, all values are positive non-zero integers.

The "battery" we are trying to simulate starts with 0%. When your program runs, the charger is automatically "plugged in", and each second the charge should tick up by 1% if the charger is plugged in, and decrease by 1% if it is not.

Each second, the program should output the amount of charge the battery has. It should not charge beyond 100% and should not go down below 0%; if the battery hits 100% then it will stay there until the charger is unplugged and if it hits 0% it will stay there until the charger is plugged in.

In addition, your program should store a "second counter" containing information on how long the program has been running for. When this counter hits any of the integers in either of the input arrays, the charger will be either unplugged or plugged in depending on which array it was in. It is guaranteed that between two "unplug" events there will be at least one "plug" event and vice versa, and it is also guaranteed that the first event is "unplug".

Whenever the charger is unplugged or plugged, a "U" or "P" should be shown, respectively.

In the case of our sample input, the charger is "unplugged" when the counter reaches twelve, 23 or 34 seconds and is "plugged" when the counter reaches fifteen, 28 or 67 seconds.

What, then, is the output of our example?

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


To be clear, the first zero should not be outputted, the charger is acted on after the corresponding second, meaning that we wait 12 seconds before unplugging the charger; the 12th second does not happen after the charger is unplugged. The program runs for the highest value in the input array, in this case 67.

The question is so the shortest answer in bytes wins. Standard loopholes are not allowed here.

• You should clarify that the program does not need to wait 1 second between each output (assuming that is the case). Also, title suggestion: Battery charging tracker or something along those lines? Apr 5 at 17:17
• @pxeger thanks for the suggestion, the program should wait 1s between each output except for the U or P indicators
– user100690
Apr 5 at 17:33

# Draw the flag of Bangladesh

The flag of Bangladesh is very simple. It looks like below:

The flag will be in bottle green (#006a4e) and rectangular in size in the proportion of length to width of 10:6, with a red circle in near middle. The red circle will have a radius of one-fifth of the length of the flag. This image will help you to understand the proportions properly:

In this Graphical output challenge, you need to draw the flag of Bangladesh like first image. Standard loopholes apply, Shortest code wins.

Resolution cannot be 0px, or echo style answers not supported.

Minimum resolution is 286*176

• I think you need to state a minimum resolution.
Apr 12 at 8:28
• @Adám what do you mean by minimum resolution? Apr 12 at 8:29
• If my output is 0px tall, then the width has to be 10×0px÷6=0px wide, and the red circle's diameter has to be 4×0px÷6=0px. Easy; here you go:
Apr 12 at 8:31
• You should also specify what the colours are and/or if an exact colour match is acceptable.
Apr 12 at 8:32
• Is ASCII art acceptable?
Apr 12 at 8:33
• @Adám ascii art is not acceptable, also in place of bottle green (#006a4e) dark green is acceptable, if you have more flaws come to chat Apr 12 at 8:35
• You had specified the color of green background. So what is the color for the circle?
– tsh
Apr 13 at 3:52
• @tsh I suppose it is #f42a41
Apr 13 at 7:46

# Saboteurs in our Halls

This is a challenge, where one member on each team attempts to sabotage their team in secret.

Similar to Red vs. Blue - Pixel Team Battlebots, bots will be divided into teams, based on the user ID number of the user who posted them. Your user ID can be found by navigating to your profile (click your icon in the top bar) and looking at the URL:

https://codegolf.stackexchange.com/users/[user-id]/[display-name]


For example, my user ID is 66833: https://codegolf.stackexchange.com/users/66833/caird-coinheringaahing

If your ID is an even number, then you are on the Red team.
If your ID is an odd number, then you are on the Blue team.
There is no way to change teams.

As you cannot change your user ID, and to prevent one team flooding the field with bots, each user may only submit one bot

## How the KotH will work

At the start of the game, each bot will be placed in a random cell in a $$\1000\times1000\$$ cell grid. No bot will be placed on the same cell as another bot, or within 5 cells of another bot. Additionally, $$\999\$$ random cells will be filled with 1 food. These cells may be any cell on the board that doesn't contain a bot.

The aim of the game is to collect food. Each bot will navigate their way around the grid, attempting to gather food. The team with the most food at the end of the game wins.

However, one bot will actually be a saboteur. This bot will appear to be a member of one team, but will instead act in a manner that helps the other team. When writing your bot, you should consider the existing bots on the opposing team and try to write in a sabotage tactic that will help them without being overly obvious.

Let's say that for this specific match, the saboteur is Blue. Their actions should aim to help the Red team win, while not giving themselves away to the Blue team. If either team suspects that bot to be the saboteur, they can then act in a preventative manner towards that bot. If Blue wins, the saboteur has failed, and so will get no points when the rest of Blue does. If Red wins, then the saboteur has succeeded, and thus gets 2 points. No matter which team the saboteur is on, each member of the winning team always gets 1 point.

Which bot is the saboteur is randomly chosen at the start of the game and remains constant until the game ends. There is only ever one saboteur per game.

The game is broken up into turns. Each team acts on alternating turns, so Red moves, then Blue, then Red etc. or the other way around. Each turn, each bot will be passed a list of game data, detailed below, and will return an integer between $$\1\$$ and $$\9\$$ inclusive, indicating which direction it would like to move in:

The bot is at $$\5\$$ before moving.

The bots for each team are called in a random order each turn, but none of them move until they all have returned values.

After all bots in a team have returned their movement choice, all moves happen at the same time. If two bots on the same team attempt to move into the same cell, neither bot moves. If a bot tries to move out of bounds, nothing happens. If a bot moves into a cell with food, it adds that piece of food to the amount it has already gathered. Initially, all bots have gathered $$\0\$$ food.

If a bot moves into a cell containing an enemy bot, the two bots fight. The winner is determined by which bot has gathered the most food. The winner then "steals" the losers food, adding it to their total gathered food. The loser is then removed from the board and re-placed at a random location not within 5 cells of another bot, and with an initial $$\0\$$ food again. If both bots have the same amount of food, then both bots are removed and re-placed, and any food they had is randomly placed in empty cells around the board.

After $$\10000\$$ turns, the game ends. Each team has their total gathered food counted, and the team with the most food wins. The actual competition will have $$\100\$$ games played. If a team wins a game, each team member receives 1 point. However, if the saboteur's team (the one it's on, not the team it's helping) wins, the saboteur does not get this point. If the saboteur's team loses, the saboteur gains 2 points.

The team with the most total points of all its bots at the end of $$\100\$$ games wins.

You should include in your answer 2 functions: move and sabotage. move is the function that will be called each turn when you aren't the saboteur and sabotage will be called each turn that you are the saboteur.

Both functions will receive the same arguments:

• x and y. The x and y coordinates of your bot, each an integer between $$\0\$$ (top-left corner) and $$\999\$$ (bottom-right corner).
• food. The current amount of food you are carrying. Initially 0, and changed by the controller for you when necessary.
• t_near. A list of bots on your team within a square, side length 33 cells, centered on you. Each bot is represented by a list containing their x and y coordinates, the amount of food they're currently carrying, and the CGCC ID of their poster.
• e_near. A list of bots n the opposing team within a square, side length 33 cells, centered on you. Each bot is represented by a list containing their x and y coordinates, the amount of food they're currently carrying, and the CGCC ID of their poster.
• f_near. A list of coordinates of all food within a square, side length 33 cells, centered on you. Each food is represented by a pair [x, y] representing it's coordinates
• team_chat. A list of all chat messages sent between your team.

Messages

In order to allow inter-game cooperation, each team will have a "chat" ability. Each bot will be passed team_chat, an array containing the chat history of that team - i.e. a series of strings saying more-or-less whatever you want. The most recent message will be at the end of the array. Each bot may, on each turn, append up to 3 messages to the chat. Each message must be no longer than 100 characters, and will be prefixed with the ID of the bot who sent it (with a space after the ID).

For example, if a bot with a user ID of 1234 sent Hello, World! to the chat, the message would be 1234 Hello, World!.

## Example Submission

This is Joey. Joey isn't too smart, and hasn't got the hang of proper sabotage. If not the saboteur, Joey just hunkers down and waits for the game to end. Otherwise, he moves around the board aimlessly in random directions:

import random

def move(x, y, food, t_near, e_near, f_near, team_chat):
return 5

def sabotage(x, y, food, t_near, e_near, f_near, team_chat):
return random.randint(1, 9)


## Rules

Any attempted gaming of the rules will lead to a disqualification of your bot. If you break any rules, your bot will be disqualified until it is fixed (if possible).

• You may only edit your answer within 12 hours of posting to prevent answers that continually optimise against new bots. You may not delete and repost your answer in order to try to circumvent this restriction
• Your code must not take longer than half a second (give or take a few milliseconds) to return its move
• You may not attempt to modify the controller or other bots' code; attempt to communicate outside of using the team chats; make web queries; or do anything malicious.

I'll keep an eye out for other unsportsmanlike behaviour, such as stealing code verbatim from other answers or using sock puppets to mess with the other team.

You are welcome to collaborate and scheme with your team, but keep the contest friendly and ethical. We don't need or want this to devolve into anarchy.

You will have 2 weeks from the posting of the challenge to submit bots. After which time, I'll run 100 games with 10000 turns each and determine the winner

# Meta

• Is this clear enough?
• Is this a duplicate?
• I'm not sure whether to write this in Python or Javascript. On the one hand, I'm better at Python, but Javascript is more popular/used. Thoughts?
• Tags are , , . Suggestions?
• Any further feedback?
• Very nice challenge :) Just one thing: have you considered letting bots know about the food quantity of nearby bots (in t_near and e_near)? I think it could give the saboteur a little more room to do his job (like kamikaze against enemies if they have more food than he does). Otherwise, it seems to me that there aren't many ways for the saboteur to help the enemy team, but maybe I just haven't given it enough thought. Apr 11 at 16:14
• Also, do you plan to do anything to prevent unbalanced teams (i.e. teams of different sizes)? It seems to me that having one less teammate is almost as bad as having a saboteur in your team, although this is probably because (as I said above) I still haven't found many effective strategies for the saboteur. Apr 11 at 16:18
• @Delfad0r Yeah, that sounds like a good idea, editing in the food suggestion for t_near and e_near. I'm not sure about dealing with unbalanced teams (it seems as though it wasn't a problem with Red vs Blue, which gives some kinda hope) Apr 11 at 16:25
• @Delfad0r Nope, that's a mistake - fixed Apr 12 at 13:32

# The Meeker numbers sequence

• I've edited the draft a bit, mainly "The Challenge" section to be more in line with the standard [sequence] rules (which is what I think you were going for). I've also cleared up some of the wording. Feel free to revert/rollback if you dislike my changes Apr 11 at 13:57

# R.E.P.A.I.R. T.H.E. K.E.Y.B.O.A.R.D.

• This is a very good challenge, apart from one thing - help mode is FAR too overpowered. I could take +, * and h (in Python), and write the password as chr(1+1+1.....) +chr(1+1+1.....) and write all of the characters that way, using multiplication to ease the process. Though, without it, I think this becomes a very interesting challenge, especially for languages like Befunge-98/<><, which would be unable to do as such. An idea would be to ban +/*, or add a penalty for using it, though I'm just throwing ideas around at this point, so take my upvote. Apr 11 at 9:37
• @StackMeter i reduced help mode to take one key only Apr 11 at 9:59
• Thanks - that should cover any loopholes. Apr 11 at 10:27
• Are functions/programs allowed to share auxiliary definitions? For instance, if two of my programs need a function for (say) computing the factorial, do I count the bytes of this function once or twice? Apr 11 at 10:52
• @Delfad0r you have to write seperate programs for different keys, and so unlike your example you have two use the function twice instead of once, and it will doubled in the byte count. But don't worry its not code golf! Apr 11 at 11:15
• DISALLOW WHITESPACE!!!!!!!!! I cannot stress this enough. Apr 12 at 9:34

# Make it prime with the smallest suffix

Posted

• "Your solution must work for the largest integer your language supports" If my language support integers in 0~n. Is this means my program should support all inputs in range 0~n? Or is this means my program should support all inputs when connect it with its output, the result of connection still in 0~n?
– tsh
Apr 14 at 3:07
• Java has support to signed 64 bit integers as long type. But Java also have java.math.BigInteger support. By saying "largest integer your language supports", does it means I must working on BigInteger instead of long or int types?
– tsh
Apr 14 at 3:11
• @tsh my intent here was that Java users would have to do that, yes. Considering that java isn't that popular of a golfing language to begin with, I'm not really concerned about the insane verbosity that brings. I am, however, considering bringing the cap to $2^{53}-1$ since that's the largest odd integer that can be represented with double-precision floats. Apr 14 at 16:05

# Posted

• There's many challenges which have this as a subproblem, but no exact dupe I could find. Apr 12 at 5:34
• Presumably, code-golf? And add decision-problem array-manipulation Apr 12 at 6:45
• Heh, lots of solutions to this exact problem were presented at the recent APL conference.
Apr 12 at 8:29
• Given how trivial this is, I'd suggest just limiting it to digits 1 to 9, as the overall approach isn't going to change much in list-based languages, but it'll allow string based languages (e.g. Retina) to compete better/easier. Also, as far as I can tell, this is, somehow, not a dupe Apr 12 at 13:09

# Sr. 4Der says make this shape! (Episode 1)

• I feel like it might be better if the answerers just chose the character they wanted to use, and then this would be a kolmogorov-complexity challenge.
– user
Mar 25 at 13:18
• "Adjust the size if needed" isn't a very precise requirement. What's the smallest valid solution? What are the necessary and sufficient requirements for a solution to be valid? Mar 25 at 14:26
• I've edited this down to a stub now that it's been posted to save space Apr 22 at 0:25

# Leave a wake of dead cells behind you

• What if this is impossible? Mar 24 at 15:44
• @Beefster Then I'll happily accept a proof of impossibility Mar 24 at 16:24

# Sum over an Interval

• I'd suggest just describing the input format ("begins with either ( or [, then 2 integers separated by a comma, ends with either ) or ]") as it's clearer. Related, but not a duplicate. Additionally, will the input always be positive (or non-negative) integers, and will the range ever be empty? Apr 20 at 18:58
• @cairdcoinheringaahing fixed Apr 20 at 21:02

# Best Rolling Ao5

• I'd suggest removing [rubiks-cube] and replace it with [array-manipulation and [floating-point]. I'd also recommend not requiring a trailing 0 if the output is only 1 decimal place (e.g. 28.3 for the last example) and mentioning that the sets are overlapping ("computing the ao5 for each overlapping set of consecutive five times") Apr 19 at 22:26
• @cairdcoinheringaahing I want to keep the trailing zeros because that's how all times are displayed in official results. Does that make sense
– qwr
Apr 21 at 3:24

# Is this number part of a Collatz prime sequence?

A fast step of the Collatz sequence is defined as

$$s_\mathrm{Collatz}:\mathbb{N}_\mathrm{odd}\to\mathbb{N},\quad n \mapsto \frac{3\cdot n+1}{2}.$$

Given an odd positive integer $$\n\in\mathbb{N}_\mathrm{odd}\$$, your task is to decide whether or not both $$\n\$$ and $$\s_\mathrm{Collatz}(n)\$$ are prime numbers.

Your program should output two distinct and unique values to represent truthiness and falseness, whereby falseness may also be represented by signalling an error.

Since $$\n+\frac12(n+1)=n+\lceil\frac n2\rceil\$$ for odd $$\n\$$, the sorted sequence of all numbers which result in truthiness in the above sense is equal to the tail of A158709.

## Test cases

-8 -> -        ; undefined behavior
1  -> false    ; (3*1 +1)/2 = 4 is not prime
3  -> true     ; (3*3 +1)/2 = 5 is prime
5  -> false    ; (3*5 +1)/2 = 8 is not prime
7  -> true     ; (3*7 +1)/2 = 11 is prime
11 -> true     ; (3*11+1)/2 = 17 is prime
15 -> false    ; 15 is not prime
91 -> false    ; (3*91+1)/2 = 137 is prime, yet 91 is not
97 -> false    ; (3*97+1)/2 = 146 is not prime

• What is the definition defining? Is $p$ a Collatz prime iff it's a prime and $\frac{3p+1}2$ is a prime? If $p$ a Collatz prime iff it's a prime and $\frac{2p-1}3$ is a prime? Or is a prime Collatz if either of those conditions hold? Sep 13 '19 at 10:56
• @PeterTaylor are they not the same thing? Sep 13 '19 at 11:09
• Alternative phrasing: which of $p_1$ and $p_2$ are you calling a Collatz prime? Sep 13 '19 at 11:11
• @PeterTaylor I mean $p_1$ Sep 13 '19 at 11:22
• So neither the input prime nor the Collatz prime need to be prime? Sep 17 '19 at 7:56
• "Input MAY be non-prime, in which case the output is always false (see 15)" -- did you specifically define this behavior or why is the above the case? Sep 17 '19 at 8:00
• @JonathanFrech I'm (personally) only interested in going from prime to prime, but I wanted to define the haviour for non-prime input. When I say 'may be non-prime' I mean, it should be able to handle it, it's an allowed/expected input but not one that gives a True output. Sep 17 '19 at 10:55
• To me it feels like an unnatural extra constraint. Sep 17 '19 at 12:54
• @JonathanFrech it's just defining how to behave with certain inputs. Sep 18 '19 at 9:12
• Citing Exceptional edge cases; such out-of-place definitions are generally frowned upon. Sep 18 '19 at 9:56
• @JonathanFrech I've changed the initial ask, and now it shouldn't be an exception Sep 18 '19 at 10:23
• Cf. A158709. Sep 18 '19 at 10:53
• @JonathanFrech Do you think this is postable? Apr 27 at 1:17
• cf. Things to avoid when writing challenges: Prime numbers. Unless there's a mathematical way to avoid any of the existing golfed primality test methods, a task involving primality test is not very interesting. Apr 28 at 6:09
• @Pureferret I would not post it -- unless you can think of an interesting golf opportunity. You could, however, improve the problem at hand: there are many questions one can ask about Collatz trajectories. And if you ask for something along the lines of "decide if the given number is a multiple of the length of its Collatz trajectory", you get a less arbitrary connection of concepts whilst preserving the topic of divisibility. Apr 28 at 14:28

• How exactly are "printing" and "returning" distinguished? Are submissions required to be a function that also outputs to STDOUT in addition to returning a value from the function? Also, I would strongly advise against subjective criteria like having an error message related to tabs, unless they are purely for brownie points; point bonuses, especially ones that can't be judged objectively, are discouraged.
– hyper-neutrino Mod
Apr 17 at 17:26
• Printing and returning can be considered identical to each other for the purposes of this challenge. Apr 17 at 18:58
• I've edited this down to a stub now that it's been posted to save space Apr 28 at 14:15

# Solve the Alien Probe puzzle code-golfarray-manipulation

• The description was clear to me, without watching either video. Doesn't seem like the wording needs much improvement. Apr 28 at 13:54

# Drawing the Mathematics Stack Exchange logo (ASCII Logos 2)

The goal is to create the Mathematics Stack Exchange logo using ASCII characters.

It looks like this.

The exact output should look like this:

                   _
/=/ \=\
/=/       \=\
|             |
|\=\       /=/|
|   \=\ /=/   |
|      |      |
_    |      |      |    _
/=/ \=\  \=\   |   /=/  /=/ \=\
/=/       \=\  \=\|/=/  /=/       \=\
|             |    |    |             |
|\=\       /=/|         |\=\       /=/|
|   \=\ /=/   |         |   \=\ /=/   |
|      |      |         |      |      |
|      |      |         |      |      |
\=\   |   /=/           \=\   |   /=/
\=\|/=/                 \=\|/=/
/=/   |   \=\           /=/   |   \=\
|             |         |             |
|\=\       /=/|         |\=\       /=/|
|   \=\ /=/   |         |   \=\ /=/   |
|      |      |         |      |      |
|      |      |    _    |      |      |
\=\   |   /=/  /=/ \=\  \=\   |   /=/
\=\|/=/  /=/       \=\  \=\|/=/
|    |             |    |
|\=\       /=/|
|   \=\ /=/   |
|      |      |
|      |      |
\=\   |   /=/
\=\|/=/
|


You must make sure the cubes should be symmetrical just like the original logo, and must make space to create a 6-point star in the middle. Yes, the output looks messed up, but it's all I can do to really make a shape.

Remember, 6 boxes aligned as a hexagon.

Can you draw it with the least bytes possible?

Tags: ,

Any suggestions?

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