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

Follow the Path

Posted here.

Answer 2

Fermat's Last Theorem, mod n

It is a well known fact that for all integers \$p>2\$, there exist no integers \$x, y, z>0\$ such that \$x^p+y^p=z^p\$. However, this statement is not true in general if we consider the integers modulo \$n\$.

You will be given \$n\$ and \$p\$, which are two positive integers with \$n>1\$. Your task will be to write a function or program to compute all positive integers \$x, y, z<n\$ such that \$(x^p+y^p)\$ and \$z^p\$ give the same remainder when divided by \$n\$.

Input

Any reasonable method of input is allowed. E.g. two separate user inputs, ordered pair, two function parameters, etc.

Output

Any reasonable method of output is valid, it may be produced by a function or output to the screen. The order the triples are listed does not matter. Triples such as (1, 2, 3) and (2, 1, 3) are considered distinct, and all distinct triples should be listed exactly once. No invalid/trivial triples such as (0, 0, 0) should be output.

Examples

n p -> Possible Output
----------------------------------------------------------------
2 3 -> []
3 3 -> [(1,1,2),(2,2,1)]
3 4 -> []
4 3 -> [(1,2,1),(1,3,2),(2,1,1),(2,2,2),(2,3,3),(3,1,2),(3,2,3)]

Scoring

Shortest code in bytes with no standard loopholes wins.

code-golf number-theory

Answer 3

Sort and Table a Sentence by Word Lengths

In as few bytes as possible, sort the input, a delimited string OR list/vector/array of words containing printable ASCII except space into a table (or something resembling a table). I tried to make the table rules as code friendly as possible to allow golfing and non-golfing languages alike to compete. Table rules are as follows:

• optional order, shortest to longest or vice versa, letter counts are required

• formatting is not the challenge, but to repeat the above rule, letter count is required. So as long as the output is some form of numerically labelled rows of words, a numbered list, or a list of lists, or similar output, then it is a satisfactory answer.

• including/excluding gaps (NA values, see below examples for both methods of output)

• Word case is untouched. How the word appears in input should be shown in output.

Input 1:

Code Golf and Coding Challenges Meta

Output 1:

 1. NA
 2. NA
 3. and
 4. Code Golf Meta
 5. NA
 6. Coding
 7. NA
 8. NA
 9. NA
 10. Challenges

or

3. and
4. Code Golf Meta
6. Coding
10. Challenges

or

[[3, ['and']], [4, ['Code', 'Golf', 'Meta']], [6, ['Coding']], [10, ['Challenges']]]

Input 2:

My very excellent mother just served us nine pizzas. #JusticeForPluto

Output 2:

1. NA
2. My us
3. NA
4. very just nine (alphabetized version: just nine very)
5. NA
6. mother served pizzas (mother pizzas served)
7. NA
8. NA
9. excellent
10. NA
11. NA
12. NA
13. NA
14. NA
15. NA
16. #JusticeForPluto

or

2. My us
4. very just nine
6. mother served pizzas
9. excellent
16. #JusticeForPluto

or

[[2, ['My', 'us']], [4, ['very', 'just', 'nine']], [6, ['mother', 'served', 'pizzas']], [9, ['excellent']], [16, ['#JusticeForPluto']]]

More examples can be provided if necessary but I think this should suffice for now. Please give me pointers, this is my second attempt at a challenge. (the first failed dramatically)

Answer 4

Sand timer puzzler (code-golf)

I was googling for a sand timer and found this little item: set of joined sand timers, for 3, 4, and 5 minutes each.

That of course reminded me of multiple puzzles about measuring X minutes using only M- and N-minute timers or whatever.

The mission then, if you choose to accept, is:

write a program that takes 3 integer inputs 0<A<B<C<100
and outputs list of all possible times that can be measured
using 3 joined sand timers A, B, and C up to 2 hrs

Test cases:

[in progress]

Answer 5

Guessing the subset.

Preface

I've never done a cops-and-robbers challenge before, so I'd appreciate some help to get this right. In particular, I'm not sure how much I should specify a (language-neutral) API. I'm also not sure how to implement time limits on computation time. (I want to be able to run a trial in seconds, not weeks.)

---

This challenge is based on Math Stack Exchange question "Guessing a subset of {1,...,N}".

In this challenge, the robber's job is to choose a subset \$R \subseteq \{1,\dots,N\}\$, kind of. Then the cop's job is to deduce the robber's subset by asking questions.

---

Robber

When I was growing up, I would sometimes play Twenty Questions with my brother. I would pick some sort of animal, and answer his questions about it. However, when he guessed the answer I had in mind, I would try to come up with another animal that satisfied all of the same answers to his questions—and if I could do it, I would tell him he was wrong.

The robber's job is similar to my strategy in Twenty Questions. The cop will ask the robber questions about the robber's chosen subset, but the robber can keep changing the subset as long as the answers are consistent. The robber's job is trying to answer the questions in such a way as to maximize the number of questions the cop needs to ask, always ensuring that the answers do not contradict each other.

Cop

The cop's job is to successively pick subsets starting with \$C_1 \subseteq \{1, \dots, N\}\$ and ask the question, "Does \$C_1\ = R\$, and if not how many elements do \$C_1\$ and \$R\$ have in common?" (That is, \$|C_1 \cap R|\$.)

If \$C_k = R\$, then the cop has finished the interrogation, and her score is \$k\$. Otherwise, the cop then can use this information to choose a new set \$C_{k+1}\$, and ask the same question for \$C_{k+1}\$.

Rules

Both the cop and robber will be given a number \$N\$, then the cop will go first outputting a subset \$C_1 \subseteq \{1,...,N\}\$. The robber will then take this as an input and output \$|C_1 \cap R|\$. The cop will take this number as an input and output \$C_2\$ and so on.

For a given interrogation both the cop's and robber's score is \$k\$ where \$C_k = R\$ is the last, correct guess. Naturally, the cop is trying to minimize her score while the robber is trying to maximize his.

Each cop will be tested against each robber (perhaps multiple times) with varying values of \$N \leq 1000\$. The score for the cop and robbers will be the sum of the scores over all interrogations.

Answer 6

Name the hydrocarbon

A hydrocarbon is a chemical compound which consists of only hydrogen and carbon atoms. For this challenge, we will only consider the three simplest kinds of hydrocarbons: alkanes, alkenes, and alkynes with no branches.

An alkane with \$n\$ carbon atoms contains \$2n+2\$ hydrogen atoms. An alkene with \$n\$ carbon atoms contains \$2n\$ hydrogen atoms. An alkyne with \$n\$ carbon atoms contains \$2n-2\$ hydrogen atoms.

Each kind of hydrocarbon is named with a prefix indicating the number of carbon atoms it contains, followed by the suffix ane, ene, or yne if it is an alkane, alkene, or alkyne respectively. The numerical prefixes are as follows:

1  -> meth
2  -> eth
3  -> prop
4  -> but
5  -> pent
6  -> hex
7  -> hept
8  -> oct
9  -> non
10 -> dec

For example, we can see propane has 3 carbon and 8 hydrogen atoms, and heptyne has 7 carbon and 12 hydrogen atoms.

Challenge

Your task is to write a function or program that receives two integers, representing a number of carbon and hydrogen atoms, and produces or outputs the name of the corresponding hydrocarbon. Capitalization does not matter, and leading/trailing whitespace is allowed.

The input and output can be in any convenient format. You may assume the input will correspond to a valid hydrocarbon, and there are at most 10 carbon atoms.

Examples

Input -> Output
1 4   -> Methane
3 8   -> Propane
7 12  -> Heptyne
10 20 -> Decene

Rules

• No standard loopholes.
• Shortest code in bytes wins.

code-golfkolmogorov-complexitychemistry

Answer 7

Numbers without 'E'

In this trial, I wish for us to think only of digits and digit compounds, from two to six trillion. If any in this group contains, in a plain Latin writing form, an indication of what our prompt prohibits, it is cast out of this group.

If a digit or digit compound contains 100, 1000, or similar, "1" is not a part of its plain Latin writing form. 1000 would simply boil down to "thousand", although 4000 is "four thousand".

What you must do:

Taking an input of N, in which N is not as high as 1000, nor as low as 0, (0 < N < 1000), and in which N is an ordinal, output what N points to in an array that follows our titular prompt.

Additionally, your solutions may contain only a solitary count of this cast out latin symbol (including diacritical marks and such, although this should not dismay you too much).

Your aim is to do this with a minimum bit count in your program.

This following portion is for clarification on what I am in pursuit of: 1 -> 2 (two) 3 -> 6 (six) 5 -> 32 (thirty two) 22 -> 1004 (thousand four) 100 -> 30 000 (thirty thousand)

Meta:

As you may have noticed, this is a little hard to read. I tried to spice it up by excluding any instance of the letter 'e' from the text description.

• Should the challenge be changed to "evaluate if a number contains 'E'"? This is an alternative idea Id considered but Im not sure if it would make a better challenge
• Does eliminating all instances of 'e' from the description make this challenge unreadable?
• Does the additional challenge of only having 1 'e' in the solution add too much to the challenge?
• Are the bounds too restrictive/not restrictive enough?

Answer 8

What's that frequency?

This is my first code-golf challenge, so apologies if it is a little unclear/already has been done. I gave the past challenges a good look over, but I may have missed something.

Create a function or a full program which accepts a frequency value, and then outputs the closest musical note, and the octave, this frequency corresponds to.

This function/program should support eight full octaves worth of notes, starting from C0 up to and including B8.

Test cases:

440.00 -> A4
466.16 -> A#4
466.20 -> A#4
261.63 -> C4
16.35 -> C0
0.00 -> C0
7902.13 -> B8
10000.00 -> B8

A full list of frequencies and notes they correspond to can be found here: https://pages.mtu.edu/~suits/notefreqs.html

This is a code golf, so shortest code wins!

Answer 9

plan an efficient finnish bus stop on a sphere

code-challengetest-battery

Apparently respecting personal space is very important at finnish bus stops. Now given some "minimum-personal-space-angle" \$\vartheta\$, your job is designing a bus stop on a sphere for as many people as possible respecting the "minimum-personal-space-angle".

Let us rephrase this a little bit more clearly: Let \$S^2 = \{x \in \mathbb R^3 \mid \Vert x \Vert_2 =1 \}\$ be the unit sphere in \$\mathbb R^3\$. Given the angle \$\vartheta \in (0,\pi)\$ you should find a set \$U \subset S^2\$ such that all pairs of vectors \$x,y \in U\$ (\$x \neq y\$) are at least an angle of \$\vartheta\$ apart, that is \$x \cdot y \leqslant \cos \vartheta\$.

And this set \$U\$ should be as large as possible - but this does not mean that your program needs to find the largest possible \$U\$ (this is a hard unsolved problem), but it should try to make it as large as possible as this will be part of the score.

Let us define \$a_\vartheta = \vert U \vert\$ as the number of vectors your program found for \$\vartheta\$.

The score \$s\$ of your submission will be

$$ s=\frac{1}{N}\sum_{n=1}^N a_{\vartheta_n} w_n$$

where \$\vartheta_n = 1/n\$, \$w_n = 1/n^2\$. And you can choose \$N \in \mathbb N\$ as large as you want.

Inspired by this reddit thread.

META:

I think the choice of \$\vartheta_n\$ and \$w_n\$ needs some fine tuning to make the challenge interesting. My thoughts so far: The idea is that \$a_{\vartheta} \leqslant c \frac{1}{\vartheta^2}\$ since every vector on the sphere needs a circle of a radius that is at least \$\vartheta/2\$, so the area of such a circle is about \$\pi (\vartheta/2)^2\$ which means we can fit at most \$\frac{4\pi}{\pi (\vartheta/2)^2} = \frac{1}{\vartheta^2}\$ (just as a rough estimate).

So I think with current choice of \$\vartheta_n\$ and \$w_n\$ the score should be bounded. But I fear that with the current choice of these sequences the greatest score will be achieved by a relatively simple solution where someone just chooses \$N=1,2\$ or so.

Can we alleviate this by adding a factor of \$\log n\$ to \$w_n\$? Unfortunately I think this would incentivise using very large \$N\$.

---

EDIT: Instead of using \$\log n\$ I think using a bounded increasing sequence would work. E.g. \$(1-1/n)\$ so \$w_n = \frac{1}{n^2}(1- \frac{1}{n})\$.

---

If you have any thoughts or ideas, please share!

Answer 10

Roll for Initiative!

Tags: code-golfmathsorting

Introduction

In tabletop games like Dungeons and Dragons, when you begin a battle, all involved parties roll for initiative. In DnD 5e, this is 1d20 + DEX + Other bonuses, where DEX is the bonus given by your Dexterity stat. The characters that roll higher numbers go first. We'll use a similar, deterministic system in this challenge.

The Challenge

Write a program or function that, when given a list of characters, will output a list of characters in order of initiative.

A character is defined as this:

character = {
    name: "name" // a string
    statblock: [SPD, DEX, WHT] // a list of numbers
                               // DEX = dexterity, SPD = speed, WHT = weight
}

The formula for initiative is the following: $$\text{Initiative} = \left\lfloor{ \frac{\text{SPD}^2}{\sqrt{\lvert\text{DEX}\rvert}} }\right\rfloor - \text{WHT}$$

Input

A list of characters, unsorted. This can be a JSON object, a list of lists, a list of dictionaries, a series of strings etc.

It is guaranteed that all names will be unique.

Output

A list of characters, or character names, sorted by initiative order from highest to lowest, based on the above formula.

Rules

• IO can be used with any convenient method.
• Standard loopholes are forbidden.
• This is code-golf, so smallest program wins!

Sample IO

Input --> Output
[[Name, SPD, DEX, WHT], ...]
    --> [[Name, SPD, DEX, WHT], ...] (or [Name, Name, ...])
---------
[[Alice,1,2,3],[Bob,10,5,0],[Charlie,3,2,1]]
    --> [Bob, Charlie, Alice]
// Alice = -3, Bob = 44, Charlie = 5

[[Z,1,1,1],[B,1,1,1],[XY,5,1,1]]
    --> [XY, Z, B]
// Retain the order of characters from the input if they have the same initiative.
// Z = 0, B = 0, XY = 24

[[Neg,-3,-3,-1],[SomeNeg,5,-2,-4],[NoNeg,4,6,8]]
    --> [SomeNeg, Neg, NoNeg]
// Negative values are valid.
// Neg = 6, SomeNeg = 13, NoNeg = -2

[[Flo,1.5,2.5,3.5],[MoreFlo,2,2.5,3.5]]
    --> [[MoreFlo,2,2.5,3.5], [Flo,1.5,2.5,3.5]]
// Floats are also valid.
// Flo = -2.5, MoreFlo = -1.5

[[Lonely,1,2,3]]
    --> [[Lonely,1,2,3]]
// Input with 1 item.

[]
    --> []
// Empty input leads to empty output.

Answer 11

Count the length of head movement

Moved here

Answer 12

Sort By the New Alphabet

The order of the alphabet is really quite arbitrary. I propose a new ordering of the alphabet, ordered so that adjacent letters (in capital form) are similar in shape. Here is the order:

JUOQGCDPRBEFTILVYXKHAMWNZS

Of course, this makes a lot of previously written code redundant. To fix this problem we will start re-implementing that code, in its updated form.

Your task is to create a program or function that takes a string or list of characters as input, and outputs that string/list sorted according to this new ordering.

You can assume that all input will contain only uppercase alphabetic characters.

---

I know it's similar to this and this, but this challenge has a fixed ordering, so I hope this allows for some more ingenuity as well as the requirement to store the ordering efficiently.

Answer 13

edit: check it out live here!

Play Big 2 by yourself, as fast as you can

Answer 14

Challenge posted to Main here

Answer 15

Expand a road network

code-golf string ascii-art

---

You've been employed as a city planner _{(obligatory seinfeld clip)} and you have been tasked with expanding the road system of Codegolfville. Here's a diagram of what Codegolfville could look like:

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

Your job is to expand the existing infrastructure \$n\$ blocks in a specific direction.

The Challenge

1. Take two inputs - a direction to expand in, and the number of blocks to expand - through any reasonable input format.

2. Expand the existing roadways in the ASCII map, in the direction specified.

   a. You must take into account the existing roadways - you can only expand on roads that are already there, and if there are no roads to expand, you won't expand anything.

   b. Your program must work for any example map, not just the one provided above.

3. Show the output on STDOUT, if your language supports it.

Test Cases

        will be done soon

Other Rules

This is code-golf, so lowest score in bytes wins. Standard loopholes are forbidden. Have fun!

Answer 16

Union of Two Polygons

Given two intersecting polygons as input, output a third polygon that is the union of the two input polygons, that is to say, the perimeter that encloses all points present in at least one of the two input polygons.

Example inputs/outputs

2 Squares

  [(0, 0), (0, 2), (2, 2), (2, 0)]
| [(1, 1), (1, 3), (3, 3), (3, 1)]
==> [(0, 0), (0, 2), (1, 2), (1, 3), (3, 3), (3, 1), (2, 1), (2, 0)]

... more to come

Notes and Rules

• Input will be two lists of at least 3 2d points each, taken in any convenient format.
• Output should be a list of 2d points, in any convenient format.
• It does not matter which point you list first.
• It does not matter whether you output in clockwise or counterclockwise order.
• Polygons may be concave
• You may assume that both polygons are not self-intersecting
• You may assume that the polygons overlap in at least two places exclusively via edge-edge crossings rather than vertex-edge intersections, vertex-vertex intersections, or flush edge-edge overlaps.
• You may assume that the polygons do not overlap in such a way that the union would have at least one hole in it.
• You must be accurate to at least 0.01 for all polygons between -100 and 100 units along each axis.
• Standard rules apply. Shortest code wins.

geometry code-golf

Answer 17

Make an "implicit" parser code-golf arithmetic string

In this task, given an infix expression, fill in all of the implicit inputs and evaluate this expression with the other given input. (You only need to deal with (+, -, and ().)

Expressions are only allowed to be dyadic and not monadic. If an operator is monadic, prepend an input.

What do I do?

The rule is simple: if something is preceded with a nilad or a parenthesized expression, it is a dyad.

+ is a dyad here:

2 + 1
(5 + 2)
3 + ((2) + 4)

Otherwise, the operator is a monad.

+ is a monad here:

 +(2 - 2)
(+ 2)

If you find a monad in your code, immediately prepend it with the a character.

a +(2 - 2)
(a+ 2)

That's about it.

Examples

The input expression is guaranteed to not produce errors, such as the format 2- which is impossible to prepend an input.

"+++a",2 -> a+a+a+a = 2+2+2+2 = 8
"(+1)+(-1)",5 -> (a+1)+(a-1) = (5+1)+(5-1) = 10
"+(2-a)", 3 -> a+(2-a) = 3+(2-3) = 2
"(5+2)+2+1", 7 -> (5+2)+2+1 = 10
"--2", 2 -> a-a-2 = 0-2 = -2

Rules

• This is code-golf, so the shortest code wins.
• Standard loopholes are disallowed.

Answer 18

Asyncronous Breakfast

I haven't seen any asyncronous challenges here, even tho it's an important part of coding, so here's my idea, based on an example (https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/) that explains asyncronous coding:

You are making breakfast. The things you want to serve are:
Cooked eggs, Bacon, Coffee, Orange Juice and Toast.

You start boiling the eggs, cooking the bacon, making coffee, and toasting toast. 
When everything is finished, you're serving the orange juice.

After every finished food, the console outputs "[Food] is ready."

Answer 19

Blackjack

This is kept fairly simple, compared to a real Blackjack-Game:

Write a program that creates a blackjack game, where the input "h" means "hit" and "s" means "stand". Everything else outputs nothing, it just waits for the right input.

Rules:
- You can draw as many cards as you want, also to make it easier, there is no card limit.
  This means you could draw more than 4 Asses.
- The cards you can get are
  standard-cards (2-10, J, Q, K, A) where the Values are the default ones:

2-9 = 2-9,
10, J, Q, K = 10

- A is a special card. So to make it easy, the default value is 11.
  If a player gets over 21, the value gets reduced to 1.
  In the case that a player has two or more A-Cards, all but one A
  reduces to 1, giving a total value of 14 for 4 Asses. (11+1+1+1)

- The dealer needs to get in between 18-21. If the bank has reached a value in 
this radius,
it can't draw another card (For example: Bank reached 18.
                          It can't get another card to get closer to 21)

- The game runs forever
- hit means „draw another card“, stand means „stop with cards and wait for 
the dealer to reach his limit“

Procedure:

- The player gets 2 cards at the beginning, shown by "Player:" in the console 
  (Example: Player gets 2 and 5 at the beginning. 
  Console output: "Player: 2, 5").

- The cards can be shown in the console by their values
  (For example: 2, 10, 1 | No need for: 2, K, A), but you can also use 
  the card-names instead. Your choice. But you need to show the maximum
  value you have
  (for example:
  first draw console output "Player: 2, 4, 5 = 11",
  second draw console output "Player: 2, 4, 5, 7 = 18")

- The input by the player is "h" for "hit" and "s" for "stand". Also allowed 
  is 1 and 0

- In the console, the player is displayed by "Player:"
- In the console, the dealer is displayed by "Dealer:"

- After the player got two cards, the dealer gets one card.
  Then the player can hit or stand.
  After every card drawn from the player,
  the dealer gets another card until he reaches his limit. (18-21)

  If the dealer reaches 21 before the player does, the dealer wins.
  If the Player reaches 21 first, the player wins.
  If the dealer reached his limit, and the player stands on the same value, it's a draw.
  If the dealer is over 21 first, the player wins.
  If the player is over 21 first, the dealer wins.

- At the end you get the output "Win", "Lose", "Draw",
  or "Blackjack", depending on the game

This game is a code-golf challenge, even the smallest result won'tbe under 150 bytes at least

Answer 20

Decorate the Christmas Tree

Tags: code-golfascii-art

Intro

It's a week before Christmas and the your family just bought a Christmas tree. Your little sister has a box of ornaments which she wants you to decorate the tree with.

Challenge

Write a function or program to randomly decorate the tree with all the ornaments from the box. All possible arrangements of ornaments on the tree must have a non-zero probability of occurrence.

Input

1. height of the tree n
2. 'box' of ornaments (a string of printable ascii characters where each character represents an ornament) in which order doesn't matter. Also, you can assume that '#' will not show up as an ornament since it is used to draw bare branches.

Given the number of branches on a tree of size n is (n-1)^2 you can assume that the number of ornaments in the box will be less than or equal to the number of branches on the tree.

Example of a box of ornaments: o = '**@@***@@$$**OOOO....'. Since this string is 21 characters long it can only be valid input for n > 5.

Output

Print out the tree with its decorations

The tree is the following structure of ascii characters where n specifies the height of the tree:

//Tree where n=9                         //Tree where n=6
        #                                        #
       ###                                      ###
      #####                                    #####
     #######                                  #######
    #########                                #########
   ###########                                  |||
  #############
 ###############
       |||

Bare branches will always be represented with '#' and the bottom trunk is always ||| while centered with center character of each row.

Examples of output with ornaments:

//n=9, o='X@@X%%%**&&'                   //n=6, o='OO*X*X'
        #                                        O
       ##%                                      O##
      #X###                                    #X#*#
     ###@##%                                  *######
    #&#######                                #####X###
   #@######X##                                  |||
  #####%##*####
 ##*######&#####
       |||

Rules

• IO can be used with any convenient method.
• Standard loopholes are forbidden.
• This is code-golf, so smallest program wins!

Meta

• Is this too close to a duplicate?
• Are there any improvements or clarifications required?

Answer 21

For any integer a and any positive odd integer n the Jacobi symbol is defined as follows: $$ \left(\frac{a}{n}\right) = \left(\frac{a}{p_1}\right)^{\alpha_1} \left(\frac{a}{p_2}\right)^{\alpha_2} \cdots \left(\frac{a}{p_k}\right)^{\alpha_k} $$ where $$n = p_1^{\alpha_1}p_2^{\alpha_2}\cdots{p_k^{\alpha_k}}$$ is the prime factorization of n. The Legendere symbol is defined for all integers a and odd primes p as $$\left(\frac{a}{p}\right) = \begin{cases} 0 & \text{if $a \equiv 0 \pmod{p}$},\\ 1 & \text{if $a \not\equiv 0 \pmod{p}$ and for some integer $x$: $a \equiv x^2 \pmod{p}$},\\ -1 & \text{if $a \not\equiv 0 \pmod{p}$ and there is no such $x$}. \end{cases} $$

Your task is to write a function that will take two parameters: a and v, where a is a positive integer, and v is a list of n values. The function should return the index of the first value in v for which the Jacobi symbol is -1. For this challenge, you may assume that all values in the v array are odd primes, and are greater than or equal to a. The length of v will be between 4 and 100 values. If no value in v produces a -1 result for the Jacobi symbol, simply return the length of v.

Because each invocation of the function will execute very quickly, your function will be tested against a wide variety of inputs and the execution time will be summed. This process will be repeated 50 times and the best execution time will serve as your score. My machine is a 2018 Macbook Pro, with the following specs:

CPU: Intel(R) Core(TM) i9-8950HK CPU @ 2.90GHz
machdep.cpu.features: FPU VME DE PSE TSC MSR PAE MCE CX8 APIC SEP MTRR PGE MCA CMOV PAT PSE36 CLFSH DS ACPI MMX FXSR SSE SSE2 SS HTT TM PBE SSE3 PCLMULQDQ DTES64 MON DSCPL VMX EST TM2 SSSE3 FMA CX16 TPR PDCM SSE4.1 SSE4.2 x2APIC MOVBE POPCNT AES PCID XSAVE OSXSAVE SEGLIM64 TSCTMR AVX1.0 RDRAND F16C
machdep.cpu.leaf7_features: SMEP ERMS RDWRFSGS TSC_THREAD_OFFSET BMI1 HLE AVX2 BMI2 INVPCID RTM SMAP RDSEED ADX IPT SGX FPU_CSDS MPX CLFSOPT
GPU: Intel UHD Graphics 630 1536MB
RAM: 32GB 2400MHz DDR4

fastest-code

Answer 22

Even-Odd chunks

(Inspired by the Keg utility of this challenge)

Given an input string, e.g. s c 1= e(a"E"), split the input into even-odd chunks.

Example

This input string, when mapped to its code points, yields the list [115, 32, 99, 32, 49, 61, 32, 101, 40, 97, 34, 69, 34, 41]. When applied modulo-2 for every item, this returns [1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1].

In this list let's find the longest possible chunk that is consistent with even and odd code points:

[1, 0, 1, 0, 1], [1, 0, 1, 0, 1, 0, 1, 0, 1]

For the first chunk, this yields [1, 0, 1, 0, 1] because this is the longest chunk that follows the pattern

Odd Even Odd Even Odd Even ...

or

Even Odd Even Odd Even Odd ...

. Adding another codepoint into [1, 0, 1, 0, 1, 1] breaks the pattern, therefore it is the longest possible even-odd chunk that starts from the beginning of the string.

Using this method, we should split the input into chunks so that this rule applies. Therefore the input becomes (the ; here is simply a separator; this can be any separator that is not an empty string):

s c 1;= e(a"E")

Rules

• This is code-golf so the shortest solution wins. Let it be known that flags don't count towards being in the pattern. They also don't count towards byte count in this challenge.

Answer 23

Convert Character Substrings to Numeric

I often have to take character data and categorize it numerically. A common thing I do is to take character type variables and convert them to numeric type characters, keeping same categories according to the level of work I'm doing. (The longer the substring, the more in depth, shorter substrings for broad level). Enough backstory...

The challenge: In as few bytes as possible, convert the input part A, a vector/list of unique strings, into the output, a vector/list of numbers, keeping unique categories within the length of substrings the same length, which is input part B.

Input:

1. w, Vector/list of unique strings of equal character length. n <= 10

   • These strings may be any combination of uppercase letters and numbers. Sorry if it seems my examples follow a pattern, I just created them after a similar pattern I see in the data I work with.

2. s, where 1 <= s <= n

Output: May take input and output in the same order, or you can convert alphabetically, but output in the same order. See example 2. (I've included comments in my output to clarify, this is not required)

Example Input 1:

#Already alphabetized, but this input is not always guaranteed

s = 3, w = 
[ABC01, 
 ABC11,
 ABC21,
 ABD01,
 ABE01,
 ABE02,
 ACA10,
 ACA11,
 ACB20,
 ACB21]

Example Output 1:

[1, #ABC
 1, 
 1, 
 2, #ABD
 3, #ABE
 3, 
 4, #ACA
 4, 
 5, #ACB
 5]

Example Input 2: s = 4, w =

[X1Z123,
 X1Z134,
 X1Y123,
 X1Y134,
 X1Y145,
 X1Y156,
 X1X123,
 X1X124,
 X1X234,
 X2Z123,
 X2Z134,
 X2Z222,
 X2Z223,
 X2Z224]

Example 2 Output:

#Categorize by order
[1, #X1Z1
 1,
 2, #X1Y1
 2,
 2,
 2,
 3, #X1X1
 3,
 4, #X1X2
 5, #X2Z1
 5,
 6, #X2Z2
 6,
 6] 

OR if conversion follows alphabetical formatting,

#Categorize alphabetically, but output in same order as input.
[6, #X1Z1
 6,
 5, #X1Y1
 5,
 5,
 5,
 3, #X1X1
 3,
 4, #X1X2
 1, #X2Z1
 1,
 2, #X2Z2
 2,
 2] 

Answer 24

Partial tq interpreter code-golf interpreter

In this task you are expected to provide a list output given an input tq program. The tq programs will not contain whitespace inside them. (I find tq extremely difficult to implement within a short time, therefore I consider it to be a nice challenge.)

What is tq, in the first place?

tq is a lazy-evaluated language that is designed with the idea that array items should be accessable during the definition of them. In tq, there is no explicit separator of an array, only special arrangements of monadic/dyadic functions and nilads.

The following program is a program printing [123] (Pretend that tq doesn't support strings because we aren't dealing with them in this case):

123

This defines a list with the first item being the number 123, after which all items in the list will be outputted inside a list.

In tq, numbers are supported to allow multiple-digits. So this defines a list with 2 items:

12+12,5

In this test case, you are expected to output the list [24,5]. Let's explain it step by step.

12+12   # This evaluates 12 + 12 in the current item in the list, returning 24
     ,  # A separator. This separates two items when they could be potentially
        # ambiguous when they are applied without a separator.
      5 # This evaluates 5 in the current item in the list, returning 5
        # The comma is simply a no-op that doesn't require parsing.

So you think that tq is not hard at all to implement? Well, remember that tq also has a special feature of accessing the items in an array before the array is defined!

555th123

We introduce two new atoms:

• t (tail) means access the last item in the list
• h (head) means access the first item in the list

Therefore our list is going to yield:

[555,123,555,123]

Now take a look at this program:

555ps123

We introduce 2 more atoms:

• p Yield the next item before (previous) the current position
• s Yield the next item after (succeeding)the current position

This yields the list:

[555,555,123,123]

A quick reference of the tq language

Just assume that you only have two operands for the operators.

• [0-9] starts a number. Numbers will only be positive integers, i.e. no decimals and negative numbers.
• , This is a separator of different items when it is given that two consecutive indexes will be ambiguous with each other without a separator. In tq all of the remaining characters can act as a separator, but in this case it is a good idea to implement only , for the ease of your implementation.
• + and * These are arithmetic operators. Usually in tq, they may be applied multiple times, e.g. 1+2+3, but in your implementation, input will be provided so that this will not happen and only 1+2 will happen (there will not be applications multiple times).
• t return the last item in the list. If the code is t1,2,3 it shall return [3,1,2,3].
• h return the first item in the list. If the code is 1,2,3h it shall return [1,2,3,1].
• p returns the item before the current item. If the code is 0,1,p,3,4 the code shall return [0,1,1,3,4].
• s returns the item after the current item. If the code is 0,1,s,3,4 the code shall return [0,1,3,3,4].

More test cases

• 4p*p will yield [4,16]
• 1p+s2 will yield [1,3,2]
• 1,2,3h+t4,5,6 will yield [1,2,3,7,4,5,6]
• 3ppss6 will yield [3,3,3,6,6,6]
• You also have to implement multiple hops. E.g. 1th should yield [1,1,1]
• If you know that something is going to form a loop, e.g. 1sp2, the cells that form the loop should be removed. Therefore the previous example will yield [1,2].
• Out of bounds indexing will yield the closest index of the indexed item that is a number. E.g. 1,2s should yield [1,2,2]

Answer 25

Internal Truth Machine code-golf

It's a normal truth machine but instead of taking input, it uses the first character of the program. Thus, internal.

Example: 0abcd prints 0 and halts, and 1abcd prints 1 infinitely.

Answer 26

Balanced interval tree code-golf fastest-algorithm

You will write a balanced, online interval tree.

• A function, method, or procedure that performs insertion into a query of intervals that overlap with an interval over a, b in O(log n) time, given that a is less than b, including:
  • intervals that fully enclose a, b
  • intervals fully within a, b
  • intervals that start to the left of a but end before b
  • intervals that start to the right of a but end after b
• A function, method, or procedure that performs insertion ov an arbitrary interval a,b into a data structure in O(log n) time
• Both O-bounds must hold after arbitrary series of insertions and queries

Requirements

If you write non-method functions, your submission may take the data structure as a global variable or receive the data structure as the first parameter.

You must informally prove your submission falls within the required O-bounds or name the data structure your program implements. If the name of the data structure you are implementing is obscure, you may name the paper of the data structure.

This is code-golf, so the submission with the shortest length in bytes wins.

Answer 27

Posted: Find the Inverse Neighbor Pairs code-golfnumber-theory

Answer 28

floating-point error matters

Write a expression of floating-point numbers in any languages. When calculating the expression without floating-point errors (as what a human do), it should be 0. But with floating-point errors (as what happened in your language), it yield 1 instead.

• Floating-point numbers are some numbers which store a finite number digits (binary or decimal or in any other bases) of fraction, plus an exponent in computer. It may be IEEE 754, but not must be.
• Loss of precision due to integer types (which do not has a exponent) are not allowed in the expression. You are still allowed to include integers (or even other types) in your expression as long as operations such as rounding into an integer are not the root of errors.

Shortest codes win as code-golf.

---

Sandbox:

• Is there any duplicates here?
• Is asking for an expression instead of full program allowed?

Answer 29

No title yet.

By Zekendorf's theorem every non-negative integer has a unique representation as the sum of Fibonacci numbers where no two numbers coincide or are adjacent.

In The minimum fibonacci challenge! the challenge was to output the list of Fibonacci numbers. However, you can instead consider the list of coefficients of the sum \$ \small x_0F(2) + x_1F(3) + x_2F(4) + \ldots \$ (since \$ \small F(0) = 0 \$ and \$ \small F(1) = F(2) \$ never appear in the Zekendorf representation) and represent that as a binary number \$ \ldots x_2 x_1 x_0 \$, e.g. \$ \small 67 = \small 1F(2) + 0F(3) + 1F(4) + 0F(5) + 1F(6) + 0F(7) + 0F(8) + 0F(9) + 1F(10) \$ which we can represent using the binary number \$ \small 100010101 \$ or \$ \small 277 \$ in decimal.

We can readily convert the binary representation back into the original integer by calculating the sum of the relevant Fibonacci numbers. However, I would like you to, given an input integer \$ \small n \$, output the decimal integer whose binary representation encodes the Zekendorf representation of \$ \small n \$ in this way.

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

Answer 30

Calculate Mahjong points

Introduction to Mahjong tiles

Mahjong (麻雀) is a board game that originates from China. Mahjong tiles used in this challenge are in Unicode points U+1F000 – U+1F021:

🀀🀁🀂🀃🀄🀅🀆🀇🀈🀉🀊🀋🀌🀍🀎🀏🀐🀑🀒🀓🀔🀕🀖🀗🀘🀙🀚🀛🀜🀝🀞🀟🀠🀡

They are categorized as:

• Winds (風牌): 🀀(East Wind), 🀁(South Wind), 🀂(West Wind), 🀃(North Wind)

• Dragons (三元牌): 🀄(Red Dragon), 🀅(Green Dragon), 🀆(White Dragon)

• Ten Thousands (萬子): 🀇(One of the Ten Thousands) through 🀏(Nine of the Ten Thousands)

• Bamboos (索子): 🀐(One of the Bamboos; note that it depicts a bird) through 🀘(Nine of the Bamboos)

• Circles (筒子): 🀙(One of the Circles) through 🀡(Nine of the Circles)

• Winds and Dragons are together called Honors (字牌).

• Ten Thousands, Bamboos and Circles are each called a suit and together called Numbers (数牌). They have ranks from 1 to 9.

• Among Numbers, the Ones and the Nines are called Terminals (老頭牌). The Twos through the Eights are called Simples (中張牌).

• Honors and Terminals are together called Orphans (幺九牌).

Every Mahjong tiles have 4 copies of themselves.

Mahjong Hand

A legal Hand will be given as the input. It consists of:

• A Head, which is 2 identical tiles.

• 4 Bodies, each which is either:

  • A Sequence, which is 3 consecutive Numbers of the same suit.

  • A Triplet, which is 3 identical tiles.

Hence, a Hand consists of 14 tiles.

There are exceptions. See "Seven Heads" and "Thirteen Orphans" below.

Points

The objective is to calculate how many points a Hand has. Points are gained by having Yakus (役), which are cumulative.

Also I apologize that I named these Yakus to be more intuitive for the code golf, making them differ from the 'usual' names. Sorry!

1 Point Yakus

• Menzen Tsumo (門前清自摸和), which is worth 1 point, will always be assumed.

• Pinfu (平和): Get a non-Dragon Head and 4 Sequences.

  • Example: 🀃🀃🀇🀈🀉🀑🀒🀓🀔🀕🀖🀟🀠🀡

• One Pair (一盃口): Get 2 identical Bodies.

  • Example: 🀂🀂🀂🀇🀇🀇🀈🀉🀓🀓🀔🀔🀕🀕

• Dragon Triplet (役牌): Get a Triplet of Dragons. Multiple Dragon Triplets are cumulative.

  • Example: 🀆🀆🀆🀇🀈🀉🀊🀊🀒🀓🀔🀛🀜🀝

• All Simples (断幺九): Let the Hand consist only of Simples.

  • Example: 🀈🀉🀊🀓🀓🀓🀚🀛🀛🀜🀜🀝🀠🀠

2 Points Yakus

• Seven Heads (七対子): Get 7 Heads. It cannot contain 2 identical Heads.

  • Example: 🀀🀀🀂🀂🀆🀆🀈🀈🀊🀊🀐🀐🀛🀛

• Colorful Sequences (三色同順): Get a sequence for each suit, consisting of the same set of ranks.

  • Example: 🀀🀀🀁🀁🀁🀉🀊🀋🀒🀓🀔🀛🀜🀝

• Full Sequence (一気通貫): Get 3 sequences of the same suit, consisting of ranks of 123, 456, and 789.

  • Example: 🀀🀀🀁🀁🀁🀇🀈🀉🀊🀋🀌🀍🀎🀏

• Semi-Orphans (チャンタ): Let all Heads and Bodies have at least 1 Orphan.

  • Example: 🀀🀀🀁🀁🀁🀇🀈🀉🀐🀑🀒🀡🀡🀡

• Concealed Three (三暗刻): Get 3 Triplets.

  • Example: 🀀🀀🀁🀁🀁🀊🀊🀊🀋🀋🀋🀑🀒🀓

• Colorful Triplets (三色同刻): Get a Triplet for each suit, consisting of the same rank.

  • Example: 🀀🀀🀉🀊🀊🀊🀊🀋🀓🀓🀓🀜🀜🀜

• Dragons Minor (小三元): Let the Head and 2 Bodies consist of Dragons. Cumulative with the 2 Dragon Triplets.

  • Example: 🀄🀄🀅🀅🀅🀆🀆🀆🀊🀋🀌🀒🀓🀔

• All Orphans (混老頭): Let the Hand consist only of Orphans. Supersedes Semi-Orphans. Cumulative with Seven Heads.

  • Example: 🀁🀁🀂🀂🀃🀃🀆🀆🀇🀇🀏🀏🀘🀘

• Three of a Kind (一色三順): Get 3 identical Bodies. Supersedes One Pair.

  • Example: 🀅🀅🀇🀇🀇🀈🀈🀈🀉🀉🀉🀙🀚🀛 (Note that this example also presents Semi-Orphans, which makes it supersede Concealed Three.)

3 Points Yakus

• Two Pairs (兩盃口): Get 2 pairs of identical Bodies. Supersedes One Pair and Seven Heads.

  • Example: 🀃🀃🀇🀇🀈🀈🀉🀉🀑🀑🀒🀒🀓🀓

• Semi-Terminals (純チャンタ): Let all Heads and Bodies have at least 1 Terminal. Supersedes Semi-Orphans.

  • Example: 🀇🀇🀇🀈🀉🀍🀎🀏🀏🀏🀏🀙🀙🀙

• Semi-Flush (混一色): Let the Numbers consist of a single suit.

  • Example: 🀂🀂🀇🀈🀉🀉🀉🀉🀊🀋🀌🀌🀍🀎

6 Points Yaku

• Flush (清一色): Let the Hand consist of a single suit of Numbers. Supersudes Semi-Flush.

  • Example: 🀇🀇🀇🀈🀉🀉🀉🀉🀊🀋🀌🀌🀍🀎

Yakumans

Yakumans (役満) worth 13 points, and supersede all Yakus above. Multiple Yakumans are cumulative.

Without Yakumans, the points are capped at 13.

• Concealed Four (四暗刻): Get 4 Triplets.

  • Example: 🀀🀀🀉🀉🀉🀌🀌🀌🀒🀒🀒🀞🀞🀞

• Thirteen Orphans (国士無双): Collect all 13 Orphans, plus an additional Orphan.

  • Example: 🀀🀁🀂🀃🀄🀅🀆🀇🀇🀏🀐🀘🀙🀡

• Nine Gates (九蓮宝燈): Get Flush of ranks of 1112345678999, plus an additional Number of the same suit.

  • Example: 🀇🀇🀇🀈🀉🀊🀋🀋🀌🀍🀎🀏🀏🀏

• All Greens (緑一色): Let the Hand consist only of Green Dragons and the Twos, Threes, Fours, Sixes, and Eights of the Bamboos.

  • Example: 🀅🀅🀅🀑🀑🀒🀒🀓🀓🀕🀕🀕🀗🀗

• All Honors (字一色): Let the Hand consist only of Honors. Cumulative with Concealed Four.

  • Example: 🀀🀀🀀🀁🀁🀂🀂🀂🀅🀅🀅🀆🀆🀆

• All Terminals (清老頭): Let the Hand consist only of Terminals. Cumulative with Concealed Four.

  • Example: 🀇🀇🀇🀏🀏🀏🀐🀐🀐🀘🀘🀙🀙🀙

• Dragons Major (大三元): Get a Triplet for each of Dragons.

  • Example: 🀄🀄🀄🀅🀅🀅🀆🀆🀆🀇🀈🀉🀑🀑

• Winds Minor (小四喜): Let the Head and 3 Bodies consist of Winds.

  • Example: 🀀🀀🀁🀁🀁🀂🀂🀂🀃🀃🀃🀖🀗🀘

• Straight Flush (連七対): Get Seven Heads with Numbers with consecutive ranks of the same suit.

  • Example: 🀚🀚🀛🀛🀜🀜🀝🀝🀞🀞🀟🀟🀠🀠

• Four of a Kind (一色四順): Get 4 identical Bodies.

  • Example: 🀃🀃🀓🀓🀓🀓🀔🀔🀔🀔🀕🀕🀕🀕

• Winds Major (大四喜): Worths 2 Yakumans. Get a Triplet for each of Winds. Cumulative with Concealed Four.

  • Example: 🀀🀀🀀🀁🀁🀁🀂🀂🀂🀃🀃🀃🀖🀖

• The Septentrions (大七星): Worths 2 Yakumans. Get a Head with each of Honors. Supersedes All Honors.

  • The only example: 🀀🀀🀁🀁🀂🀂🀃🀃🀄🀄🀅🀅🀆🀆

Other rules about Mahjong

When a Hand can be interpreted as different combinations of Heads and Bodies, the combination with the most points will be chosen. (See Three of a Kind and Two Pairs above)

Examples

🀅🀅🀋🀋🀌🀌🀍🀍🀑🀒🀓🀟🀠🀡 : Menzen Tsumo + One Pair = 2 points.

🀉🀊🀋🀌🀍🀎🀑🀒🀓🀔🀔🀞🀟🀠 : Menzen Tsumo + Pinfu + All Simples = 3 points.

🀀🀀🀀🀁🀁🀁🀂🀂🀂🀃🀃🀃🀆🀆 : Winds Major + Concealed Four + All Honors = 52 points. (Most points possible)

Rules about code golf

• Input type and format doesn't matter, but it must consist of the Unicode characters above. In C++, valid examples include std::u8string (sorted or not) and std::multiset<u32char_t>.

• Output type and format doesn't matter either.

• Invalid Hands (not exactly 14 tiles, contains 5 copies of the same tile, etc) fall into don't care situation.

• If and only if your language doesn't support Unicode, use the following table to parse Mahjong tiles:

         |x0|x1|x2|x3|x4|x5|x6|x7|x8|x9|xA|xB|xC|xD|xE|xF  
  -------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
  U+1F00x|We|Ws|Ww|Wn|Dr|Dg|Dw|T1|T2|T3|T4|T5|T6|T7|T8|T9
  -------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
  U+1F01x|B1|B2|B3|B4|B5|B6|B7|B8|B9|C1|C2|C3|C4|C5|C6|C7
  -------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
  U+1F02x|C8|C9|