Sleep Forever

Write a program that never exits completely, but also after startup consumes exactly 0.0 CPU time.

This means you must sleep in a way that the operation system never wakes up the process. ps aux | grep [your program] should show %CPU 0.0 at any time after startup.

Note a long sleep in a loop is not enough, since then the OS will need to wake up your program to start the next iteration. You must absolutely never be woken up.

Waking up on signals for the purpose of exiting is OK if your language does that by default. However, no normal input over pipes should not wake your program up.

You can use CPU for any finite amount of time during startup.

This is code-golf, shortest code wins.

Meta:

I need some help with the signals exception. I don't want submissions to need to spend a large amount of code to disable all signal handlers present by default, but also I don't want programs that just "wait for a keypress" for example which isn't really reasonable.

I also want to avoid giving significant advantages to languages just because of what signal handlers they do/do not have by default.

I also want to avoid using too much OS specific terminology.

Suggestions appreciated.

Efficient Ouroboros Quine

code-challenge quine

An ouroborus quine is a program that (taking no input) outputs the source code of a different program, which in turn outputs the source code of a different program, and so on, until after some number of iterations, the result is the source code of the original program. In some cases (often called quine relays) each program is in a different language, but here all the programs forming an ouroboros should be in the same language. Let the period of an ouroboros quine, \$T\$, be the number of distinct programs involved in the loop.

The challenge is to find the most efficient ouroboros quine, achieving the maximum period using the minimum program size. Let the size, \$N\$, be the number of bits (not bytes) in the source code of largest program in the ouroboros. Your score is \$\frac{\log_2 T}{N}\$.

This formula is scaled such that the theoretical maximum score is arbitrarily close to 2, for arbitrarily large \$N\$. A score of 1 is achieved if every possible string of length \$N\$ is a valid program which forms a part of an ouroboros quine. The maximum theoretical score also requires that every possible string of length less than \$N\$ is a program forming part of the ouroboros.

As achieving an arbitrarily high score may require an arbitrarily large program, it is permitted to describe the program (and prove/demonstrate its correctness), rather than providing an arbitrarily large amount of raw code.

Sandbox Questions

• Is this an interesting (and novel) question?
• Do I need to specify the output format more precisely, or do standard guidelines on output format suffice?
• Is allowing a program description, rather than raw code, a disastrous idea? Or, conversely, is it even necessary to state that this is permitted?

Cut a Pizza into infinite number of slices using the minimum number of cuts

It is well known that with n straight cuts it is possible to cut a circle into \$\frac{n^2 + n + 2}{2}\$ pieces. This is known as the Lazy Caterer's Sequence.

However, finding the right angles to cut the circle is less easy. The areas after each cut become very small.

Your task is to find these angles. Output a infinite sequence of pairs of angles such that if you connect each pair by a line, you'd cut the circle into \$\frac{n^2 + n + 2}{2}\$ pieces. Angles may be either in degrees, radians, or any other reasonable way to measure angles, can be either floating points, fractions, or any other reasonable way to represent numbers.

As with standard sequence rules, you may:

1. Print the pairs infinitely
2. Take an input N then output the Nth chord
3. Take an input N then output the first N chords.

This is code-golf, shortest answer wins.

Continuously Count Consecutive Cases

Calculating Transitive Closure

Battle Chess Royale (Any better name?)

koth

Imagine a large chess board where different players can choose and place a chess piece. Pieces are Knights, Bishops, Rooks, Kings or Queens. Each piece has an unique movement ability and a point per turn value. The board, after an specific amount of rounds will shrink (as a battle royale field do) disqualifying any player that left its piece outside.

The goal of the game is to get as many points as you can. This can be achieved by simply staying within the safe zone of the board and killing other players to take their points.

Each piece has an specific amount of passive points per turn based on how freely it can move. Below is the table used. Feel free to give any suggestion on point distribution.

Note: Pawns are not added to the game since their movement is similar to a king

For the game, you will select which piece type you wanna play with. The function for your bot will take as a parameter a board (n x n matrix), an array with the available moves your piece can perform, a list with the next players, and finally an object with info about the game (next shrinking round, leaderboard, etc...). Your return value should be your desired move (must be from your available move array).

Bots Examples

new Bishop(function(board, availableMoves, players, gameInfo){ return availableMoves[0]; }, "Drunky Step"); 

new Rook( (board, availableMoves, players, gameInfo) => availableMoves[Math.floor(Math.random() * availableMoves.length)], "Le Rook" ) 

new Queen(function(board, availableMoves, players, gameInfo){ let targets = availableMoves.filter(move => { return board[move[0]][move[1]] != null; }); if(targets.length > 0) return targets[0]; else return availableMoves[Math.floor(Math.random() * availableMoves.length)]; }, "Killer") 

Here is an example of a 5x5 board with 2 bishops in it

Notes

• The game will be turn based.
• Players are randomly shuffled before the beginning of the game
• There is an specific amount of rounds where you cant capture anyone
• Board always shrinks towards the center
• If you die or get captured, you score remains
• It is possible to die because of board shrink, and still win the game
• There is no suicide unless you wait for board shrink

Questions:

• Has this been made?
• Config options as # of rounds, board size, how many rounds every shrink, etc... can be set up before the game. What values should I use?
• Any considerations I should take?

PD: I have most of the controller done, I'll be uploading it soon. I'm still working on some basic graphic interface.

Is this set laminar?

Calculate the aspect ratio of the Nepal flag

Apove is the picture of the flag of the country Nepal. Pretty cool.

What's cooler, is the aspect ratio, which is defined under the constitution as:

This is A230582.

Your task is to output at least the first 113 digits of the decimal expansion, in any format of your choosing.

Write a Tank AI

Preamble

This preamble will be removed in the real post.

I have created a platform to automatically run multi-language KotH. In this example, the framework will simulate an abstract battle of tanks on a grid. Each user's answer will control their tank.

The idea is that the competition will be open for a month -- after which the competition will be run offline and then the results will be appended to the Code Golf question.

I have written the proof-of-concept simulator in a way that makes it easy for people to add new competitions. It should be good enough for this first competition and then made more robust afterwards.

The title for the software is Harmagedon (which means Mount Magiddoh) because:

1. it conveys the idea of Armageddon i.e. there is a high stakes battle.
2. the mountain part gives a nod to classic King of the Hill type games.

I am interested in feedback on how the post can be worded more clearly and what information needs to be added.

Tank Battle

Write an AI to control a tank on a grid. Each player's tank is placed in a randomly, unique row and column. The number of the grid's rows and columns are each equal to the number of players.

The grid is a torus. In other words, things exiting the grid from the right-most column will appear on the left-most column (in the same row), things exiting from the upper-most row will appear on the bottom most row (in the same column), and visa-versa.

Tanks receive instructions based on the output of their code. Output is in the form of two letters and a new line.

All tanks act simultaneously in a round of decision-making called a tick.

Running code

Every tick, when the simulator needs a tank to make a decision, it runs the tank's code (passing the game state into the standard input). It then captures the standard output and performs that action (as long as it matches a valid instruction for moving or shooting).

There is a 3 second timeout for running code. Any code that takes longer to run will result in that tank not performing any action that tick.

Note: During a tick, all of the move actions will first resolve and then all of the shooting actions.

Format of Standard Input

The format of the game state will be as follows:

Game_State ::= YourUserID ';' GridWidth (';' Position)+ Position ::= TankUserID ',' XCoord ',' YCoord 

As an example, if you are user 9999 on Code Golf Stack Exchange, and the following is the starting grid:

 Y ^ | +--------+--------+--------+ | | | | 2 | [0] | | | | | | | +--------+--------+--------+ | | | | 1 | | | [9999] | | | | | +--------+--------+--------+ | | | | 0 | |[50000] | | | | | | +--------+--------+--------+-> X 0 1 2 

Then the input to your code will look like this for the 1st tick:

9999;3;0,0,2;9999,2,1;50000,1,0

Breaking it up one chunk at a time:

• 9999: You are tank 9999.
• 3: The grid is 3 squares wide and 3 squares tall.
• 0,0,2: The tank controlled by user 0 is at co-ordinate (0, 2)
• 9999,2,1: The tank controlled by user 9999 is at co-ordinate (2, 1)
• 50000,1,0: The tank controlled by user 50000 is at co-ordinate (1, 0)

Format of code output

Your output can be either a moving or shooting instruction.

Moving Instruction

• mu: Move one tile up
• md: Move one tile down
• ml: Move one tile left
• mr: Move one tile right

If more than one tank attempts to move to the same square in a tick, only one will move there and the others will remain where they were. No grantees are made about which ones stay behind (i.e. in theory non-deterministic but potentially deterministic in implementation).

Shooting Instruction

• su: Shoot upward
• sd: Shoot downward
• sl: Shoot left
• sr: Shoot right

When a tank shoots in a direction, the projectile will instantly traverse from the tank in that direction until it reaches another tank or back to its starting position. If it reaches another tank (other than the one who fired it), it will destroy that tank and remove it from the grid. If no other tanks are encountered along its path, nothing happens.

Winning

Players are ordered by the amount of time that they last on the grid. The winner is the player who doesn't die, the second placed players are those whose tanks were destroyed last, the third place are those whose tanks were destroyed second-last and so on.

Ties for places happen when more than one tank is destroyed in a tick.

Submitting

Code should be submitted as an answer on Code Golf.

The answer needs to have a very specific format so that the simulator can parse it.

The format can be described as follows.

The answer must contain at least two code blocks. The first code block should be the name of the language being used and the second should be the code being submitted.

The language can be any listed in this JSON object. Use one of the object keys to refer to which language you will use.

Note: There is a hard 1024 character limit for submissions.

Example

# This is an example submission All of this text before the next code block will be ignored: ``` python3 ``` The above code block will be parsed to find out which language to run the code in (because it's the first code block); this text, however, will be ignored because it is not a code block. The next code block will be parsed to get the code that will control this answer's tank. Normally one could add extra information here to elaborate on the solution. ``` import random stdin = input() # Get the world state # Parse the world state my_id, width, *tanks = stdin.split(';') tanks = [t.split(',') for t in tanks] # Get my position my_x, my_y = next(t for t in tanks if t[0] == my_id)[1:] # Get a list of other tanks that are in-line with me inline = [t for t in tanks if t[0] != my_id and (t[1] == my_x or t[2] == my_y)] if inline: # If one exists, other_tank = inline[0] # then shoot on that axis. if other_tank[1] == my_x: print('sl') else: print('su') else: # otherwise, move in a random direction print(random.choice(['mu', 'md', 'ml', 'mr'])) ``` Everything after this previous code block will be ignored (including other `code blocks`). 

Hashers and Crashers

Count N-Rich Permutations of an Integer Sequence

Given a sequence of integers with length \$L\$ and an integer \$1 \le N \le L\$, an "\$N\$-rich" permutation is one whose the longest strictly increasing subsequence has length exactly \$N\$.

For example, let our sequence be [0, 1, 2, 3]. There is exactly one \$1\$-rich permutation, given by [3, 2, 1, 0]. By contrast, there are sixteen \$2\$-rich permutations:

[0, 2, 1, 3] [0, 3, 1, 2] [0, 3, 2, 1] [1, 0, 3, 2] [1, 2, 0, 3] [1, 3, 0, 2] [1, 3, 2, 0] [2, 0, 3, 1] [2, 1, 0, 3] [2, 1, 3, 0] [2, 3, 0, 1] [2, 3, 1, 0] [3, 0, 2, 1] [3, 1, 0, 2] [3, 1, 2, 0] [3, 2, 0, 1] 

Note that [0, 1, 3, 2] is \$3\$-rich and NOT \$2\$-rich, because even though it contains a strictly increasing subsequence of length 2, it also contains a longer strictly increasing subsequence.

The Challenge

Your challenge is to write a function which takes in an integer sequence S with some length \$L\$, and an integer \$1 \le N \le L\$, and returns the number of N-rich permutations of S.

This is code golf, so the shortest valid answer wins.

Test cases

Each row is a sequence along with the expected output for all possible values of L. For example, the first row says that if your function is called f, then f([1, 2, 3, 4, 5], 3) = 41

[1, 2, 3, 4, 5] => 1, 69, 41, 8, 1 [1, 2, 2, 3, 3, 4, 5] => 4, 2612, 2064, 336, 24, 0, 0 [1, 1, 1, 1, 1, 1, 1] => 5040, 0, 0, 0, 0, 0, 0 [1, 2, 3, 1, 2, 3, 4] => 8, 2976, 1864, 192, 0, 0, 0 

Could it be a possible chess move?

code-golf decision-problem chess

Backstory

Professor Chesster has a library of chess puzzles with solutions, but a meteor has struck (not real, I promise) and now their hard drive may be corrupted! Luckily, Professor Chesster's puzzle FENs are stored securely, but the solutions to those puzzles have all been jumbled up and could be as ridiculous as gxm9=L or even axc3! Professer Chesster needs a quick and simple scan to check if the solutions to their puzzles are valid.

Luckily, most of the meteor is not radioactive (no radiation-hardening) but because Professor Chesster's hard drive is now a literal potato, they need the code to be as short as possible (code-golf) or it might overheat!

Stop waffling pls and show me the challenge!!!

OK, fine. Here:

Check if a move inputted with algebraic notation could be valid. Return a truthy value if it is, and a falsy value otherwise.

List of all moves that are valid

Na1, Na2, ..., Nh8 Ka1, ... ... [all other pieces] Nxa1, Nxa2, ... [captures] Nba1, ... [specify row] N2a1, ... [specify col] Nb3a1, ... [row & col] Nbxa1, N2xa1, Nb3xa1, ... (NOT Kab3 as there's only one king) O-O (or 0-0??? META - WHAT DO I DO) O-O-O (or 0-0-0??? META - THIS TOO) axb2 to axb7 bxc2 to bxc7 ... gxh2 to gxh7 then bxa1 to bxa7 ... hxg7 Then promotions (a1=Q, a1=R, a1=B, a1=N) b1=QRBN, c1=QRBN, ..., h1=QRBN a8=QRBN, ... axb1=QRBN,bxc1=QRBN, ....... [other moves I may have missed] 

Scoring

Again, Professor Chesster's hard drive is such a potato that they require it to be golfed as much as possible. (this is code-golf)

META: Mandatory duplicate check

Not a duplicate of Is it a valid chess move? as that asks about a specific position.

Not a duplicate of Is it a plausible chess move? as that doesn't include piece information and a few other things that will be mentioned below

Sandbox/Meta stuff

• Specifications
  • Do I include...
    • Check (move+)?
    • Double check (move++)?
    • Checkmate (move#)?
  • Did I miss any other chess moves?
• Funny enough backstory?

Decode Chess Move

Erasure Poetry

answer-chaining code-challenge

Given two strings of digits \$A\$ and \$B\$, count the minimum number of digits that need to be removed from \$A\$ to make it a substring of \$B\$. (META: i am still brainstorming what this actual challenge part should be, though i think this challenge might be good).

However, you will not be "writing" programs/functions to solve this challenge, so much as you will be finding them in the previous answer.

Challenge specification

(spec in progress)

Take two strings of digits \$A\$ and \$B\$. You can assume these strings will both be nonzero in length and contain any amount of the following characters in any order: 0123456789. Return the number of digits needed to be removed from \$A\$ in order to make it be a substring of \$B\$.

Worked out examples:

A: "3" B: "123" Output: 0 Explanation: "3" is already a substring of "123", so 0 characters need to be removed from it A: "1322" B: "12345" Output: 2 Explanation: "12" is the biggest potential substring of B that could be made from A, and it requires removing the 3 and one of the 2s A: "12345" B: "123" Output: 2 Explanation: "123" is the biggest potential substring of B that could be made from A, and it requires removing the 4 and 5 A: "12345" B: "67890" Output: 5 Explanation: None of A exists in B, so "" (the empty string) is the biggest potential substring of B that could be made from A, and it requires removing all 5 of the digits 

Scoring specification

Contrary to what I said in the intro, you will technically be writing a program or function to solve this challenge. However, you will not be scored directly on your code length.

Included with your answer will be a list of characters you will remove from the previous answer's code such that it becomes your answer's code. If this is not possible with removals alone, you may also add characters to the previous answer, but this will come with a score penalty.

In particular: Your score is the number of characters you need to add to some substring of the previous answer's code in order to make it your answer's code. Lowest score wins.

The first answer to base your score off of will be provided at the bottom of this post.

Answer chaining rules

Importantly, you may not answer the challenge in a language that has already been used unless your answer has a lower score. Flags and version numbers do not differentiate languages in this challenge.

(more clarifications and guidelines)

Answer chaining example

6. MyOwnLanguage, +3 characters

previous answer with removed characters replaced with *:

do ****thing *o** 

with my added characters becomes:

do thing now! 

Try It Online

7. HQ9+2, +0 characters

previous answer with removed characters replaced with *:

do*thing****! 

with my (0) added characters becomes:

dothing! 

Try It Online

Starting answer

0. JavaScript (V8), +361 characters

f = (a, b) => { const isSubstring = (c, d) => { if(!c){ return true }else{ return RegExp(`${c}`).test(d) } } if(isSubstring(a, b)){ return 0 }else{ a = [...Array(a.length).keys()] .map(w => a.slice(0, w) + a.slice(w + 1) ) a = a.map(w => f(w,b)) return 1 + Math.min(...a) } } 

Try it online!

meta

work in progresss, but feel free to suggest anything you think i might be missing, even if it seems obvious. Still working out the formatting for everything to look nice :-)

What's my score?

The question score on Stack Exchange is the total number of upvotes minus the total number of downvotes a question receives. However, the reputation gained/lost for every upvote/downvote is different (10/-2 on Code Golf).

Given the total reputation and the reputation gained/lost on votes, list out all possible scores the question could have.

Rules

• The total reputation, the reputation gained by an upvote and reputation lost by a downvote must be integers
• The upvote-reputation will be positive and the downvote-reputation will be negative
• You can output the possible question scores as a (possibly infinite) list or print each one individually.
• This is code-golf, so the shortest answer wins

Examples

[total reputation, upvote-reputation, downvote-reputation] -> [question scores] [28, 10, -2] -> [2, -2, -6, -10, ...] [34, 10, -2] -> [1, -3, -7, -11, ...] [17, 10, -2] -> [] [11, 7, -5] -> [1, -1, -3, -5, ...] [82, 31, -11] -> [2, -18, -38, -58, ...] [15, 5, -10] -> [3, 4, 5, 6, ...] 

Sum of consecutive nth powers code-golf math integer

How many ways to cut a number into an equation?

Play a game of memory

Numbers with distinct decimal digits

Implement Subleq

Do you win a Numeric Mahjong?

I (rev)?(pal)? the source code, you (rev)?(pal)? the input!

Complete an equivalence relation

In set theory, a relation from a set \$A\$ to a set \$B\$ is a set of pairs of elements from \$A\$ and \$B\$. For example, \$\{(1, 5), (1, 6), (2, 4), (3, 5)\}\$ is a relation from the set \$\{1, 2, 3\}\$ to the set \$\{4, 5, 6\}\$.

A relation \$R\$ from a set \$A\$ to itself is an equivalence relation iff:

• It is reflexive: For all elements of \$A\$, \$(a, a)\$ is in \$R\$.
• It is symmetric: If a pair \$(a, b)\$ is in \$R\$, then so is \$(b, a)\$.
• It is transitive: If the pairs \$(a, b)\$ and \$(b, c)\$ are in \$R\$, then so is \$(a, c)\$.

For example, \$\{(1, 1), (1, 2), (2, 1), (2, 2), (3, 3)\}\$ is an equivalence relation on the set \$\{1, 2, 3\}\$.

Your challenge is to, given a relation from a set to itself, add as few pairs of elements as possible to transform it into an equivalence relation.

Worked example

If we start with the relation \$\{(1, 2), (3, 2), (4, 4)\}\$, then:

Firstly, the relation must be reflexive, so all pairs of elements \$(a, a)\$ must be added, resulting in \$\{(1, 2), (3, 2), (4, 4), (1, 1), (2, 2), (3, 3)\}\$.

Next, the relation must be symmetric, so we need to add the inverses of \$(1, 2)\$ and \$(3, 2)\$, resulting in \$\{(1, 2), (3, 2), (4, 4), (1, 1), (2, 2), (3, 3), (2, 1), (2, 3)\}\$.

Finally, the relation must be transitive. Since \$(1, 2)\$ and \$(2, 3)\$ are in the relation, so must be \$(1, 3)\$, and likewise \$(3, 1)\$ must also be in the relation. Adding these results in \$\{(1, 2), (3, 2), (4, 4), (1, 1), (2, 2), (3, 3), (2, 1), (2, 3), (1, 3), (3, 1)\}\$, and this is an equivalence relation.

Input/output is can be lists of pairs of positive integers, or an adjacency matrix. You can optionally take the domain of the relation (i.e. all unique values in it). The order in which you output the pairs does not matter, and you can assume the input will be nonempty.

Testcases

{(1, 1)} -> {(1, 1)} {(1, 2)} -> {(1, 2), (1, 1), (2, 2), (2, 1)} {(1, 2), (3, 4)} -> {(1, 2), (1, 1), (2, 2), (2, 1), (3, 4), (3, 3), (4, 4), (4, 3)} {(1, 2), (1, 3)} -> {(1, 2), (1, 3), (1, 1), (2, 2), (3, 3), (2, 1), (3, 1), (2, 3), (3, 2)} {(1, 1), (2, 2), (3, 3)} -> {(1, 1), (2, 2), (3, 3)} {(1, 1), (2, 2), (3, 4)} -> {(1, 1), (2, 2), (3, 3), (3, 4), (4, 3)} {(1, 2), (3, 2), (4, 1)} -> {(1, 1), (2, 2), (3, 3), (4, 4), (1, 2), (1, 3), (1, 4), (2, 1), (2, 3), (2, 4), (3, 1), (3, 2), (3, 4), (4, 1), (4, 2), (4, 3)} {(8, 19), (4, 12), (9, 31), (4, 18)} -> {(8, 8), (8, 19), (19, 8), (19, 19), (4, 4), (4, 12), (4, 18), (12, 4), (12, 12), (12, 18), (18, 4), (18, 12), (18, 18), (9, 9), (9, 31), (31, 9), (31, 31)} {(8, 7), (2, 7), (14, 3), (3, 16)} -> {(2, 2), (2, 7), (2, 8), (7, 2), (7, 7), (7, 8), (8, 2), (8, 7), (8, 8), (3, 3), (3, 14), (3, 16), (14, 3), (14, 14), (14, 16), (16, 3), (16, 14), (16, 16)} {(1, 1), (1, 2)} -> {(1, 1), (1, 2), (2, 1), (2, 2)} 

The multiples are missing

code-golf integer sequence

Find the k-th largest number

Given the string representation of three sorted lists, get the k-th largest number.

The string representation has such form:

1 3 5 7 11 120 9988 23 68 99 111 107 131 888 

aka. lists are separated by newline \n and numbers in one list are separated by space.

Length of each list, length of the string and k are directly given, but access to the string costs. You can fetch from a given position. Least fetches wins.

Your solution should handle all possible inputs well, but only optimize score for average cases.

This is an example solution. It solves the problem with an awful score, but you can also use lib here. Write the lib if it's absent in your language.

Sorted lists in test cases will be generated in this way:

• Generate 1 million (1'000'000) integers uniformly in \$\left[0, 2^{31}-1\right]\$. Duplicates will likely appear.
• Sort them.

[Not decided yet] It's fine if your code is only optimized for three 1M length arrays and fallback to worst solution for other input.

Befunge Comment Outline Creator

Minecraft XP Orb Amounts

Intersections in a Circular Scrambled Word

Given a word W and a scrambled version of it S as input, you are required to return the number of intersections S will have when organized in a circular arrangement.

Example

Let W be VICTORY and S be VICYTRO. After transforming the scrambled word in its circular form and forming the original word by adding segments between the characters, we have the following diagram:

As we can see, for this particular example, the expected output is 2 interceptions.

Specs

• Input will consist only of [A-Z] characters.
• It is irrelevant how you set up the circular word (clockwise, counterclockwise, if the characters are evenly spaced from one another or not), just be consistent.
• Input is flexible, read it however you see fit for you.
• Standard loopholes are not allowed.

Test Cases

Format: W , S --> output VICTORY, VICYTRO --> 2 # To be added more 

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

Meta

Is the challenge interesting? Is there anything unclear? I am not a native English speaker, so I welcome any corrections on the wording of the challenge.

I will later add more test cases. Also, what is the general consensus here where there are multiple correct answers? Because when I add words with repeated letters, depending on the "path" you choose when forming the circular word, it will affect the number of intersections. (I'll update the specs section as well when I introduce these special cases).

Lastly, I didn't give much thought on my second point in the specs section, maybe it's wrong... I'll observe more cases later.

Pretty much any feedback is appreciated!

Seat gangs as far as possible

Just another traffic jam!