Sandbox for Proposed Challenges

Question

What is the Sandbox?

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

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

See the Sandbox FAQ for more information on how to use the Sandbox.

The Sandbox works best if you sort posts by "active".

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• Most people include applicable tags in their proposal, so for instance you can search for all king-of-the-hill proposals by merely adding the tag name in quotes to the search query.

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To add an inline tag to a proposal use shortcut link syntax with a prefix: [tag:king-of-the-hill]

Answer 1

Translator to Minimize the Number of Characters

With code golf you are attempting to minimize the number of characters or bytes. The languages are, however, all just ASCII characters. While I do not want to see this in other code golf challenges, can you use more exotic characters to do the job?

CJam, for example, only uses ASCII characters in its code but many other characters can be placed into the compiler as a strings. I wrote a simple translator to test this out which can be coverted to:

㉕ァײோ¸༘ݩײ౲ᖒⲫ㶚ቲ㑼ᇦ㰌⧑༘ઃ௉ⲫ௔ྭഞࠗ㒍⾺

While this is intentionally not an acceptable answer for various reasons, it shows the range of possible characters the interpreter can identify. Please note unusual things that happend as you attempt to highlight the text.

The Challenge

1. Choose an online interpreter such as Ideone, CJam, or Golfscript and a language which can be run on that interpreter. This is so I know I am using pretty much the same resources as you are when I run your answer.
2. Create a translator in your stated language which accepts an "original" input code from the same language. It then outputs a string which can be pasted in your answer or in a comment on this site.
3. Create a second translator into which the previous output string can easily be incorporated. When this combined string and translator are run, it will run the original input code.

Please note:

• The original input code to score your answer will be the same for any answers of the same language.
• This code for scoring will be subject to change and the translator must work for any code of that language the interpreter accepts. (exceptions listed below).
• This code for scoring will only contain ASCII characters and I will attempt to take it from existing answers on this site. At request it can exclude line breaks or specific characters for an additional 5% to your score AT MY DISCRESION (for instance Java code needs to be able to have spaces in it, I can't avoid that).
• The input code for scoring will be roughly 500 characters long. However, you transltors need to work regardless of the length of the input code so you can't take advantage of the fact that the code is even/odd. It does not need to work for null input.
• Any errors or anything malicious will obviously be disqualified.
• The compressed code must be copy/pastable to codegolf SE.
• When running the code from its translated form, the code must be able to accept input. This input is not going to be part of the code to be translated.
• Any null case which does not compact the original code in any way is disqualified.

Scoring

• Minimum score wins (surprise surprise)
• Score is the number of characters you need to run the original code minus the number of characters in the original input code plus 500 (combined with any modifiers).
• The length of the original translator does not matter.
• 5% is added to your score for each character/symbol your language often makes use of but your translators cannot handle. I can disqualify for this if I believe that the missing character too severly cripples the programmer.
• 5% is removed from your score if your two translators are the same piece of code (aka the translation is reversible).
• 5% is removed from your score if all characters in the compressed output are visible (no invisible ASCII characters). White space (spaces, tabs, line breaks) are visible but ASCII character 19 (for instance) is not.
• 3% is removed from your score if all characters are visually distinguishible (no two characters look the same but are read differently by the interpreter). The more obvious this is the better.
• 10% if anyone provides an acceptable example input code where the score without modifiers would be longer than the original input code. This would mean the translator effectively did not compress the input code.

Answer 2

Sudden Death Rummy

codegolf with following rules: A 50 game match is played and the winner gets an average score per game. This average score is then multiplied by the bytecount of the program. The winner is the program with the lowest product of average score and bytecount.

Rummy is a card game where the objective is to get rid of all cards in your hand by forming "melds". A meld is either a consecutive series of cards in the same suit, or 3/4 cards of different suits of the same value, which is, in ascending order A(ce), 2-10, V(alet), Q(ueen) or K(ing). A meld is always at least 3 cards, and 13 cards at the most.

In my regional variant of discard rule Rummy, there are 7 rounds. the first 6 rounds require you to put down N+2 cards in 1 or more melds, then discard 1 card, then finish your turn, before you can start using existing melds or put down new melds. in the 7th round, you NEED to be able to place down your entire hand and discard the one card in 1 turn, before your opponent can do this. You start with 10 cards, and every turn you cannot empty your entire hand, you draw another card and give the turn to the opponent. The actual system involves buying cards and bidding wars, but to simplify, it's just round robbing cards until one of them finishes.

---

Your task: Create a Rummy bot that plays against itself.

Input: a number between 1 and 100 denoting how many games should be played.

your program needs to generate 2 random legitimate hands as the first task. The deck starts with 104 cards: 2 full decks, 4 suits per deck, 13 cards per suit. 10 cards per hand from the deck.

second task: one hand randomly starts. If the program cannot make a legitimate Sudden Death Rummy hand clear, it draws a random card and hands the turn to the other hand. If the program CAN make a legitimate hand clear, it displays 2 lines. The first line is a comma-separated list displaying the winning hand clear. The second line is the sum of the value of the cards of the other hand, with number cards being their respective value and A/V/Q/K being 10 points each. this task switches between players until one of them is the winner. If the game lasts long enough for the deck to be depleted, no victor is declared and both hands get scored according to the above rules.

3rd task: after a victor is chosen, the next game starts. task 1 and 2 are repeated until there have been as many games as the input indicates. At this point, the match ends. The victor is the side who has the lowest amount of points after the end of the last game.

[Sandbox Note: I need to: Figure out a scoring method that doesn't require multiplying or averaging average score and bytecount without encouraging high bytecounts or average scores; decide whether to include a runtime limit; Decide whether the program should also display the hand and drawn cards.]

Answer 3

Build a Version Control System [WIP] code-golf

Git, SVN, Mercurial and Bazaar are just too bloated for you. You want something simple. Something as short as possible.

Rules

• Your program will be invoked every time an operation needs to be made to the repository.
• Your program must take commands from command-line arguments.
• The implementation of how the program stores its own data does not matter. Input and output format do.
• Give your version control program a name and version numbering (so I can keep track of when you update it).

Repositories

A "repository" is a directory with files and directories in it, as well as (a) special file(s) that store settings and information for the repository. These special files may not be included in version control. All other files in that directory should be included in version control.

Features

• 'init' command - sets up a repository in the working directory
  • [BONUS 20pts] If a repository already exists in the working directory, erase or reset it first
• 'destroy' command - removes all of your special version control files from the repository. If you are not in the root directory of a repository, keep moving up one level until you find VCS files. If you reach the top level of the filesystem without finding your VCS files, don't do anything.
  • [BONUS 15pts] Exit with status 1 if no VCS files are found

Scoring

Your score is the length of your code in bytes, minus all bonuses. Lowest score wins.

Answer 4

Unbreakable Wall Maria

code-golf AND ( graphical-output OR ascii-art )

In order to protect the last bastion of human civilisation against giant Titans, a large wall has been constructed around the perimeter of the city. It has been decided that another large wall, within the perimeter of the first one, will be erected to ensure the protection of the city. You have been assigned to design the wall to make sure it is strong and sturdy.

A wall of height p and length q is built out of identical rectangular blocks of height m and length n. A wall is considered unsecure if there is a straight line that can divide the wall into two pieces without cutting through any of the individual blocks. To illustrate, consider a wall of height 5 and length 6, constructed of blocks of 1 height and 2 length placed in either orientation. This is the test case 5 6 1 2 (a 5x6 wall composed of 1x2 blocks). There are at least two different ways of building this wall:

Diagram 1: Ways of building a wall

The first wall is an insecure wall because there is a line that divides the wall into two pieces (into a 6x4 block and a 6x2 block). Because there is only one line that divides the wall, we can call this wall an insecure-1 wall. An insecure-1 wall is more secure than an insecure-2 wall, but not as secure as a secure wall.

The second wall is a secure wall because there is no line that can divide the wall into two pieces without going through any of the blocks. You could also think of it as insecure-0 if you wanted to.

A secure wall is essential to the integrity of the wall. If it is an insecure wall it will be easily breached by the Titans. Your task is to design the wall. To do this, you will write a program that takes in the height and length of the wall and the blocks as input, and output (a graphical representation / an ASCII art representation) of the most secure wall that can be created using the blocks given.

Input

Input consists of four space seperated integers p, q, m, and n, which represents the height of the wall, the length of the wall, the height of the blocks, and the length of the blocks.

Output

This is the part I'm not sure about. I've got two possibilities: either I can make the question graphical output (i.e. I would expect the program to output an actual image), or ASCII art.

Possibility 1:

Output a graphical image (not ASCII art) of the wall. The overall appearance of the wall (e.g. line thickness, colours used, size, etc.) is up to you, but the lines that form the individual blocks must be clearly visible, and differentiated from the rest of the wall. This means you can't pull something like "this draws a black wall with black lines", or "this draws an infinitesimally small scaled wall", etc.

Possibility 2:

Output text based art (not a graphical image) of the wall. It should be drawn using the box drawing characters. The wall must be drawn to scale, but apart from that, you have some freedom in what characters to use (so you can choose to use the double line ones if you wish), but they have to be part of the Box Drawing Unicode block. In addition, the wall must be visible, so you can't write a program that outputs nothing and say "this draws an infinitesimally small scaled wall", etc.

Question to reader: Which output format do you think would make a more interesting challenge?

Answer 5

One digits or two digits

king-of-the-hill

Here’s the rule:

They're 2 players. Each player has a pool of $99.

The player that takes the first turn will choose to invest an amount of $$$ taken (deducted)from your own pool. Then other player will do the same.

Who invests more wins the round. Who wins the most round is the match winner.

Unless it’s not that simple.

They’re a few twist:

Your opponent know how many points you use, well almost.

After you invest, your opponent know if you invest one digit number or two digit number. They’re told instantly after you invest your points. Just one or two digits. Not precisely.

WARNING: Player who moves first still get notified about your opponent who moves second.

Your opponent know how many points you still have left in your pool, well almost.

They’re only told if you have either $0 to $19, $20 to $39, $40 to $59 points, $60 to $79 points or $80 to $99. They’re told instantly after you invest your money.

WARNING: Since the notification is instant, that means if I move second, I got to know your score level before I move. If I notice a level change when you move first, I will know the level change before I make my move second. So I can act according to it.

It’s best of 9, and those $99 must survive those 9 rounds.

So you don't want to invest all $99 in round 1. Well, it doesn’t mean that you have to spread those $99 exactly in 9 rounds. You can use those $99 in any mean to get victory. If you have a sure-fire strategy that will give you a guaranteed win, but it needs you to use all your $99 in the first 5 round, by all mean, go. Just remember that invested point don’t return back to your point pool, win or lose.

In first round, the player who moves first decided randomly. In following round, the player who wins previous round moves first. If tie, the player who moves first last round, moves first again

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SCORING METHOD

Each bot will be run double robin. The winner of the match results 1 point. Tie 1/2 point. Lose 0 point. After the match up, bot with most points declared as champion

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COMMUNICATION PROTOCOL

During your turn, I will run your program and gives you lines of query from STDIO

Each line is a query of this following type:

START

Every input start with this.

YOU xx

This means that in that round, you played xx(exact number of dollar you invested)

ENEMY x y

This means enemy invest x digit int that round (x is 1 if enemy invested 1 digit, x is 2 if enemy invested 2 digit) and y is the money level after the player invests(y is 0 for $0 to $19, 2 for $20 to $39, 3 for $40 to $59, 4 for $60 to $79, 5 for $80 to $99)

FINISH

End of query. We expect you to give us output.

Your output must be to stdout and a single positive integer (0 is allowed)

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EXAMPLE:

The match is between DEO vs WORLD. It was decided that DEO moves first.

ROUND 1

Deo will receive this query:

START
FINISH

Deo decides to invest $10. Now he only has $89.

WORLD receive this query:

START
ENEMY 2 5
FINISH

What WORLD deduces is that DEO played from $10 ~ $19. WORLD knew that DEO played at least $10 because the query said that ENEMY 2.. and WORLD knew that DEO played at most $19, because if DEO played $20, the query will be ENEMY 2 4

WORLD decides to invest $20.

In round one, DEO invests $19 while WORLD invests $20. Since WORLD invests more, WORLD receive 1 point.

Enter to round 2: WORLD starts first, since winner starts first by the rule

WORLD receive this query:

START
ENEMY 2 5
YOU 20
FINISH

WORLD decides to invest $0.

DEO receive this query:

START
YOU 19
ENEMY 2 4
ENEMY 1 4
FINISH

DEO realizes that in round 1, enemy played at least $20, due to level change. And he noticed that in round 2, enemy played 1 digit number. DEO taught that WORLD decides to save his money and invest $0. DEO decides to invest $1

WORLD invests $0 while DEO invests $1. Since DEO invests more money then WORLD, DEO win 1 point.

And so on

Answer 6

Traffic lights

Easy challenge

Write a program that that graphically shows traffic lights on a crossroads. It should output animation. There should be red, red+yellow, green, blinking green, yellow. Bonus - pedestrian traffic light.

Complex challenge

Write a program that manages traffic lights in a town. Input is a graph of roads, information about where people want to drive (i.e. in morning they mostly drive at work, in evening they return home) tied to the graph. The system models cars and reports you current positions and speeds of each car. Drivers' goals are to be inferred from statistics. Your goal is to provide the most optimal operation mode of each individual traffic light, avoiding accidents.

Questions

• Which tags to use? Should it be a code-golf?
• Which is more viable - the easy or the complicated challenge? Should I try to work the complicated one to be more CodeGolf-worthy?

Answer 7

My telephone is a computer!

code-challenge algorithm primes

I finally took the plunge and purchased a push-button telephone. It seemed a waste to just bin the old telephone, so I got working with some surplus chips and boards and things, and a soldering iron, and made it into a computer!

Now I need a program. DialCode(c) can do Prime Numbers! I think.

So I need some help with an algorithm for Prime Numbers, with the following limitations:

10 variables, which can contain any number from zero upwards, limited only by 32,767; (Var0 - Var9)

10 labels; (Label0 - Label9)

10 Machine Instructions;

EndBlock: Ends a block - if the block was actioned, implicity Continue Main is executed, 
otherwise continues with next instruction (EndBlock) 

Test > 0: Starts a block, can test multiple variables (If > 0 Var0 ...)

Test = 0: Starts a block, can test multiple variables (If = 0 Var0 ...)
 
Set variable to another variable (Var0 = Var1)

Set variable to 1 (Var0 = 1)

Set variable to 0 (Var0 = 0)

Increment variable by 1 (Var0 +)

Decrement variable by 1 (Var0 -)

Unconditional branch to label (Br Label0)

Continue MAIN (Continue MAIN)

Output variable (Output Var0)

Instructions prior to the first Test are executed only once, at the start of the program.

Continue MAIN can be within a block or a "special case" unconditional use which is the target for the completion of a non-nested block.

The first Test defines MAIN.

MAIN is executed an "installation setting" number of times. These are 10 for Testing, and 1,200 for Production.

A Test can define an internal block if appearing before an EndBlock. The completion of an internal block does not cause automatic iteration (but an explicit Continue MAIN can be used for that).

All variables are initially zero.

Example program

Var1 = 1 
If > 0 Var1 Var3 
    Var2 +
EndBlock
If > 0 Var2
    Var1 +
    Var3 +
EndBlock
Var2 +
Continue MAIN
Output Var1
Output Var2
Output Var3

MAIN is defined here by the first IF > 0. The first test is not true. The second test is not true. Var2 gets one added, and MAIN starts up again (the unconditional Continue MAIN). The first test is still not true. The second test is now true, and Var1 and Var3 get one added. Since the block was executed, there is an implicit Continue MAIN. From this point on, the first IF > 0 will always be true, its block will be executed, with another implicit Continue MAIN so the program will finish quickly.

The above program demonstrates how to implement a "case-like" structure. Put another way:

Var1 = 1
BlockControl repeat 10 times
  case
    Var1 > 0 And Var3 > 0
      Var2 +
      break
  case
    Var2 > 0
      Var1 +
      Var3 +
      break
  case
    other
      Var2 +
EndBlockControl
Output Var1
Output Var2
Output Var3

The output from the program will be 2, 9, 1.

Algorithm can be demonstrated in any language, even pseudo-code (if guaranteed to work). Explanations will probably make your Answer more popular.

It is not required to write an emulator of the CPU, only to limit your choice of instructions in your language to those logically equivalent to what is supported by the CPU. DialCode(c) itself is a subset of your language (subject to differences in syntax)!

There is no input. Output can be whatever is convenient. Feel free to use any specialist libraries, as long as they follow the above limitations.

The Winner must work to the limitations. The most popular working algorithm will be chosen. Where submissions are effectively the same algorithm, the one posted first, which I was able to understand, is the tie-breaker.

Sandbox Questions

I can't find a question here about generating Primes only using addition and subtraction. I know one way to do it, so all the guff above is to funnel thought towards a known solution. The solution I've seen uses 10 variables, 10 or fewer types of instructions, and Labels are fun, but not necessarily necessary.

Not sure of a reasonable time-limit to impose before the Accept.

When I came across an algorithm for this, I thought it was really cool. Very easy to implement without knowing how the algorithm actually works, difficult to come up with the algorithm. Great fun finding out how the algorithm works.

I would like to see a wide range of answers in a lot of languages, so that even fairly inexperienced users can have a crack at implementing. That's not going to work with one question, because I don't think it is an easy type of algorithm to develop (without foreknowledge or practice).

So I was thinking one question to get an algorithm, a second question for implementation. I was thinking of "fastest code" but that puts Assembler/compiled languages/others as the natural rankings for that.

Prompted by a comment by @isaacg, I'm now thinking "total number of DialCode(C) instructions executed" may work for a follow-up implementation question.

So, Question One - get a nice algorithm. Question Two, implement in as few DialCode(C) instructions as possible.

Any implementation is going to be Ssssslllllooooooowwwwww, with a capital S. Fewest DialCode(C) instructions is fastest code, whatever language the DialCode(C) is written in. Reasonably level playing field.

I'll have a go at the suggested shortening of the question :-)

Answer 8

This is an idea for an incremental answer-dependent question. I'm interested in comments. I will keep it here for a while and probably reword it at some point.

---

Print the name of the language of the previous answer

restricted-sourcecode-golf

The first answer to this question must print the name Code-Golf without using any letters in Code-Golf.

Each answer that follows will have to print the name of the previous language, but without using any characters in the previous program (you can use letters in the language name, but not the code they posted). Each language can only be used once.

The winner is whoever posts the most valid answers. If there is a tie, then the length of each program is added together, and the answerer with the smallest total length is the winner.

---

The main problem I see with this is that multiple people would be racing towards the next answer. Allowing people to still post answers they worked on would cause clutter, and if people sign up to be the next answerer, we could be waiting forever for one to post. You could possibly have another question for answers that were too slow.

I would also need a rule against posting extraneous characters in your program that makes it impossible for the next one.

Answer 9

Elevator Controller

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Sandbox Note

• I would love some feedback about whether you think this has enough room for algorithmic finesse to stick with code-challenge or whether it should be code-golf.
• Any kind of early questions or ideas are welcome, too.

---

Introduction

Every day on my way to work I have to take one of two neighboring elevators – and often, they are not currently on my floor, so I have to press a button and wait for it to stop by. Ever so often, I get the feeling the software behind these elevators was written by an army of monkeys who finally managed to type some program that would compile.

But it makes me think: isn't there a more clever way to manage elevators? Maybe you can help me make my way to work less annoying by implementing a new controller software!

The Challenge

You must write a complete program that takes input from stdin (or similar) and print to stdout (or similar). Your program will receive the following arguments:

• The first line consists of two space-separated numbers:
  • The number N of neighboring elevators your software will have to manage.
  • One integer H specifying the number of the top floor level for the building (the ground floor level is marked 0, so H = 5 means there are six stories).
• All subsequent lines of input are a space-separated list of two numbers in the range [0, H] with the following meaning:
  • The first integer specifies the level on which a passenger is requesting an elevator.
  • The second integer specifies the level this passenger would like to get to.

During each time tick, your program must print (to stdout or similar) one line with N characters wherein each character specifies what an elevator does (from left to right = first to last elevator). The following commands are available:

• D for "Move elevator one level down."
• U for "Move elevator one level up."
• S for "Stop the elevator on this level." This command allows any number of passengers to enter or exit the elevator on this level. This will happen automatically and people will only exit the elevator on the level they want to get to.

Furthermore, all elevators are rather small and have a maximum capacity of 2 people. So no elevator can take more than two people. Since people are generally nice, they apply a first come, first serve pattern. Passengers who are "too many" will just wait the next turn.

If two (or more) elevators happen to stop on the same level with people waiting to enter, they will start filling up the elevators from left to right.

All N elevators will start on the ground level – 0 – upon start of the program.

As always, standard loopholes apply. No cheating, no networking etc. If possible, please submit your answer with a link to an online interpreter or instructions on how to run it.

Example

Input:

2 3
2 0
3 1

Possible Output:

UU
UU
SU
DS
DD
SD
SS

Here are more examples, but to keep the post short, newlines are represented as | and input/output is separated by #:

2 3|0 1|0 2|0 3 # SS|UU|SU|UU|SS|US|SS

1 2|0 1|1 2|1 0|1 0 # S|U|S|U|S|D|S|D|S

Scoring

This is a code-challenge. There will be an unknown test case which I will only reveal after having accepted the winning answer (so you can make sure I didn't make scores up), but not before as to prevent answers optimizing for that test case only.

The score will be the number of steps your submission prints (= number of lines of your program's output). The lowest score wins with votes as a tiebreaker.

Verification

You may use the following snippet to verify your submission:

TODO (I will write this once I plan on publishing this question)

Answer 10

The Invincible Rock Paper Scissors

underhanded popularity-contest

Make a bot that plays Rock Paper Scissors with the player. The bot should prompt the user for input (either rock, paper, or scissors) and then output the result. The result should include the user's hand, the bot's hand, and who won. An example of an acceptable result output would thus be:

I played rock! You played scissors! I won!

Another acceptable output:

The bot's rock beat the player's scissors.

This is the underhanded part: the bot should always win. However, the player has access to the source code of the program, so you should try and make the part of the code that causes the bot to always win as inconspicious as possible.

Here is an example in Python 2.x. If it were posted, it would not get many upvotes because it is extremely obvious that the bot will always win. A better answer would appear to be fair to the player, but in fact still causes the bot to win every time.

user_choice = raw_input("Pick a hand (rock, paper, or scissors)...")
if user_choice == "rock":
    print "I played paper! You played rock! I won!"
elif user_choice == "paper":
    print "I played scissors! You played paper! I won!"
elif user_choice == "scissors":
    print "I played rock! You played scissors! I won!"

Concerns

My main concern with this challenge is that it may be a close duplicate of random script that isn't actually random. I am not sure if the requirement for having a different output for the user's input (while maintaining the illusion of randomness) is enough to differentiate this challenge from the original underhanded random challenge. Feedback on this issue is appreciated.

Answer 11

Calculate the Delacorte Number of a square - posted

code-golf math

Answer 12

Lua Variables From Arguments?

In this question I challenge you to get variables from function arguments in Lua. The least amount of characters wins.

Basically I'm asking for you to create a function that takes an argument, and prints out the variable as a string.

Please note it has to work in a standalone Lua console.

Answer 13

Number Datasheets code-golf

Write a program that accepts an integer n where 1 < n < 10000 and prints some facts about it. Each fact must be on a separate line, and in the order shown here.

• even or odd
• prime or composite
• deficient, perfect, or abundant
• square if it's a perfect square
• cube if it's a perfect third power
• fourth power if it's a perfect fourth power
• fifth power, sixth power, etc. as appropriate (each on a separate line)
• square-free if it has no factors that are perfect squares (except 1)
• triangular if it's a triangular number
• pentagonal if it's a pentagonal number
• hexagonal, heptagonal, octagonal, nonagonal, decagonal as appropriat
• 11-gonal, 12-gonal ... k-gonal. However, these should only be printed if k is less than n or if k is less than 10. In any event, each of these term is to be on a separate line.
• x totatives where x is the count of the numbers between 0 and n that are coprime to n
• lucky if it's a lucky number
• Fibonacci if it's a Fibonacci number
• Lucas if it's a Lucas number
• Leonardo if it's a Leonardo number
• repdigit in base b if it's a repdigit in base b, where 1 < b < n-1
  • If it's a repdigit in multiple such bases, instead print repdigit in base b, c, d
• strictly non-palindromic if it's not a palindrome in any base b where 1 < b < n-1

Any feedback would be appreciated.

Answer 14

Math golf

This challenge is about writing code that outputs the smallest formula possible for a sequence of position integers.

Input

I will choose 10 from the following test sequences of positive integers. However, please do not hardcode these into your answers. If I suspect this has happened, I reserve the right to change the test sequences without notice.

Your code should accept standard in with one list of comma separated sequences per line.

1, 2, 7

12, 9, 7, 5

40, 25, 16, 10, 7

2240, 1225, 679, 373, 213, 149, 141, 133

8064, 3969, 1969, 974, 494, 254, 164, 134, 119

118272, 53361, 24196, 10958, 5027, 2399, 1271, 863, 746, 695, 668, 665

1, 4, 36, 400, 4900

96, 1280, 17920, 258048, 3784704, 56229888, 843448320

72, 800, 9800, 127008, 1707552, 23557248, 331273800

40, 224, 1064, 3808, 21280, 59200, 322600

2240, 832, 240, 72, 20, 6, 3

53760, 17152, 4480, 1248, 384, 104, 44, 22, 11

329472, 86656, 20800, 5536, 1536, 440, 124, 44, 19, 8, 4

32800768, 6856704, 1536000, 394752, 103936, 27136, 7936, 2080, 656, 264, 132, 66, 33

206389248, 33216512, 7029760, 1743360, 448000, 112640, 30144, 8288, 2096, 688, 284, 102, 46, 18, 9

20956446720, 2527756288, 510181376, 122363904, 30720000, 7643136, 1972224, 508416, 136192, 35456, 10816, 3296, 1360, 632, 292, 146, 73

Output

A math formula per input line which maps an index n starting at 1 to the relevant value.

A formula can be made up as follows. It can consist of the sequence variable n, integer constants, *, /, -, +, !, (, ), ^ or (m,k). These are to be interpreted in their normal mathematical sense with (m,k) to be read as binomial(m,k). The formula has to be well formed with, for example, parentheses matching and the order of precedence of operators will be the usual mathematical ordering.

A special rule applies to the factorial function ! which requires parentheses if the ^ or ! operators are to be applied to the result of the factorial. I.e. it is (n!)^2 and not n!^2. Note that the !! is never allowed. Unary - also requires brackets if any further operator is applied to the result on the left hand side or if the result is to be raised to a power. For example it is n*(-1) and not n*-1.

Score

I will test your code on a number of sequences of integers that I make.

The score is the sum of the number of characters in all your outputs.

Example output

For the sequence that starts 96, 1280 above, the output 4^(n+1)*(2*(n+1))!/((n+1)!)^2 gives a score of 29.

Answer 15

Generalized Array Indexing

popularity-contest array-manipulation

Most programming languages provide an array datatype (which might be called a list or a vector) that supports indexing. Given an array and a nonnegative integer, we can fetch the element of the array at that position: [a,b,c][0] = a. Some languages, like Python, support a more general indexing system, where passing a negative index counts the position from the end: [a,b,c][-1] = c. But why stop there?

In this challenge, your task is to provide another generalization of this operation. In other words, you must provide a function that takes in an array and a number, and returns something, up to the following restrictions:

1. If a nonnegative integer is passed to the function, it must return the element of the array at that position. In other words, it must be an extension of the array indexing operation.
2. It must support more indices than just nonnegative integers, like negative integers, fractions, complex numbers, or even strings. In other words, it must be a proper extension.

If necessary, you may restrict the types of elements your arrays may contain, so you may choose to only handle arrays of, say, floating-point numbers, or other arrays. This is a popularity contest, so the answer with the most upvotes wins.

Answer 16

Play Chopsticks

Disclaimer: Please fix the question and the scoring if they are not satisfactory. I am probably not qualified to run and score entries because I am not entirely familiar with the logistics of running two programs against one another, and, as such, I will not be posting this question to the main page myself. So, if anyone wants to take this off my hands, feel free. I just really like this idea and want to see it happen.

king-of-the-hill

Chopsticks Wikipedia article

Your challenge is to write a program that, given the current position of the game as input (how many fingers on each hand), outputs the next move it chose to take.

Rules of the game

(Normal rules, no variations)

1. When a hand's finger-count becomes >= 5, it's finger-count becomes 0.
2. Splitting/transferring is allowed. You CAN bring a dead hand back by transferring some fingers from your other hand.
3. However, splitting/transferring is not allowed if the move only results in you having swapped your hands. (eg. no prolonging the game by "doing nothing")
4. A player loses if both their hands are dead.

Input

You will receive as input the number of fingers on each of your and your opponents hands.

Input will be given in the following format:

#_on_your_LH #_on_your_RH #_on_opponent_LH #_on_opponent_RH

Examples:

1 1 1 1

or

4 0 3 2

Output

Your program will output your move base on the input.

Key:

First number:
  0 (your LH)
  1 (your RH)
  2 (transfer from your LH to your RH)
  3 (transfer from your RH to your LH)

Second number:
  If first number was 0 or 1:
    0 (opponent's LH)
    1 (opponent's RH)
  If first number was 2 or 3:
    1-3 (# of fingers to transfer)

Examples:

0 0 (tap opponent's RH with your LH)
0 1 (tap opponent's LH with your LH)
1 0 (tap opponent's RH with your RH)
1 1 (tap opponent's LH with your RH)
2 1 (transfer 1 finger from your LH to your RH)
3 2 (transfer 2 fingers from your RH to your LH)

Scoring

Each entry will be made to play a game against every other entry.
If a game does not end after 100 rounds (?), it will be declared a tie.

Two points will be awarded for every win and one point will be awarded for every tie.
Entry with the most points is the king of the chopstick-hill.

Answer 17

N-gon Naming

code-golf math kolmogorov-complexity

Challenge

Given the word name of a polygon n, you must output the number of sides polygon n.

Examples

Input:  triangle
Output: 3

Input:  dodecagon
Output: 12

Input:  megagon
Output: 1000000

Input:  hexahexagon
Output: 66

Winning

The shortest code wins.

The list of shape names can be found here with instructions on how shape names are constructed. Use the alkane naming system.

Answer 18

Help Bob the Builder survive the communists, and fast!

The communists have taken over the world and you are the last remaining tower builder. In order to surive you must show that you are able to build towers and fast!

The challenge

Bob is given a set of building blocks b, and a number n of towers to build. Since we are in communist land the towers should have as equal of an height as possible. The catch is that you are only given 180 seconds to build the towers. The goal is to minimize the std of the tower height. In addition you have to build towers at three different sites. Which means three different sets of building blocks and three different set of towers.

Input & Output

blocks = [1,2,3,4,5,6,7,8,9]
towers = 3

The ouput should be on the form

7 6 2
8 5 4
1 9 5

std = 0

Here the towers are built vertically. The std is calculated as follows

std = sqrt[(mean - tower1)^2 + (mean - tower2)^2 + ...]

where tower1 represents the height of that tower and mean is the average of the heights.

mean = (tower1 + tower2 + ... + towern)/towers

Example 2

Input

blocks = [1,2,3,4,5,6,7,8,9]
towers = 2

Output

5 3 2 4 1
9 6 7 9 0

std = 0.7071

Since mean = (23+22)/2 = 22.5 and std = [(22.5-23)^2+(22-23)^2]^(1/2) = [1/4+1/4]^(1/2) = (1/2)^1/2.

These two are examples of optimal outputs. Since the problem is NP hard an optimal solution within a reasonable time is impossible.

Scoring

The blocks for the three building sizes are given below. The sum of these three tests judge your performance. Lowest score wins. Eg

 score = 100*std(1) + 50*std(2) + std(3)

Where std stands for the standard deviation obtained at building site n. Do not try to cheat and make a code that runs longer than 300 seconds. The KGB (Eg me) performs regurarly controls.

---

Question for meta

1) Is the problem clear enough? Eg use the three vectors and distribute them equally

2) Is the scoring now fair? Must have a run time beneath 3 minutes, lowest score wins.

Building site 1: 2 towers

Building site 2: 3 towers

Building site 3: 23 towers

Answer 19

Quine is love, quine is life (well, almost)

Yes, another Life challenge. Inspired by this.

Challenge

Write a program (the generator) that, when given a representation of a Game of Life board on STDIN (or in a file if you like), outputs a program which contains a string representation of a Game of Life board in its source code.

The representation will be in the following format:

 h w x1 y1 x2 y2 x3 y3 . . . xw yh

where:

• h = height of the grid
• w = width of the grid
• xi yi = coordinates of a live cell

When run, the new program should output its own source code - with a catch: the string in the output must represent the generation following the one previously encoded. (We shall call this program the replicator.)

Other stuff

• All live cells will be provided as input, so all other cells may be assumed to be dead.

• 0,0 is at the bottom left.

• Both programs (the generator and the replicator) need not be in the same language.

• There may be a width-one border around the string representation for a -10% bonus in score.

Scoring

Your score on a particular input will be defined as the length of the generator plus the average length of the first 100 generations of the replicator.

Your final score will be the average of your scores on all the test cases. The lowest score wins!

---

Question

Should we impose a format for the string representation, like maybe

* * * * * * * * * * * * * * * * * * *
*                                   *
*                                   *
*                 *                 *
*               *                   *
*               * * *               *
*                                   *
*                                   *
*                                   *
* * * * * * * * * * * * * * * * * * *

or should we let the GolfScripters and CJammers of PPCG use their unprintable black magic? :D

Answer 20

Query the icosahedral graph

code-golf

You've been sent back in time to 1973 to change history by remaking a clone of Hunt the Wumpus. You need to code a network of rooms in the game that forms an icosahedral graph, whose vertices correspond to the 12 vertices of the icosahedron connected by edges, unlike the dodecahedral graph used in the original game. Each room connects to five others.

Your goal is to write a program or function that takes the ID numbers of two of the twelve rooms, and returns one value if the rooms are adjacent, and a different value if not. Due to space constraints, you code needs to use as few bytes as possible.

You can choose what ID's to label the 12 rooms, but due to hardware constraints, they must be numbers from 0 to 255. Specifying the ID's doesn't count for the code length.

Input

Two distinct ID numbers from 0 to 255 out of 20 of your choice. You can't restrict which order two numbers appear in.

Output

A consistent value for pairs of numbers that correspond to adjacent rooms in your ID scheme, and a different consistent value for non-adjacent pairs.

Your code may not use any built-ins that represent the dodecahdral graph or related structures.

Answer 21

Reverse Polish Notation-ing!

Your challenge is simply to write a function which converts a given arithmetical expression into it's Reverse Polish Notation form.

Input

Your function will be passed in an arithmetical expression, as a string, which may contain any of +-*/^() or a space. For example:

1+1 34 * 7^6 3 * (78 + 7)

Output

Your function should return the Reverse Polish Notation form of the input with a space between each number. The above inputs would output:

1 1 + 7 6 ^ 34 * 78 7 + 3 *

Scoring:

This is code-golf so shortest code wins. Bonuses are as follows:

• -15 for supporting brackets in the input (as in: ())
• -5 for supporting exponents (as in: ^)
• -10 for supporting floating point (decimal) numbers (formatted with a dot: 12.56)

You should support, at minimum, +, -, * and / operations.

Good luck!

---

To the sandbox:

• Should I give more examples or is 3 enough?
• Do you think the deductions are a fair amount off? Too much? Too little?
• Am I missing something really obvious? (I usually am!)

Answer 22

Print the Twelve Days of Christmas with twelve programming languages

Use twelve programming or scripting languages to write twelve programs, embedded within each other, to print the lyrics for Twelve Days of Christmas.

Each program will write the next program to file, compile if needed, and execute it. The parent processes will not exit until the last has executed. When they exit, they will print the final verse, program by program. You may only have one file to start with. You may also, optionally, have a text file with each line of the song in it.

You must specifiy any dependencies needed to run the programs. For example, if you need a compiler, such as GCC, or PHP or the Java compiler/Java, put them in a list of dependencies.

For example:

<?php
echo "On the first day of Christmas, my true love gave to me:\nA partridge in a pear tree!\n";
$code = <<<EOD
public static void main(String [ ] args) {

String nextCode = new String;
System.out.println("On the second day of Christmas, my true love sent to me:");
System.out.print("Two Turtle Doves\nand a Partridge in a Pear Tree\n");
nextCode = "(Next code to be written is in here)";
PrintWriter writer = new PrintWriter("thirdDay.c", "UTF-8");
/*
* and write the next program, in this case, thirdDay.c to file and so on....
*/
}
EOD;
file_put_contents("secondDay.java", $code);
exec("javac secondDay.java");
echo exec("java secondDay");
echo "and a Partridge in a pear tree"; // runs after the other twelve have run
?>

Apologies for my rusty Java.

To reiterate:

1. The program is started
2. The program prints the appropriate verse
3. The program writes the source code for the next program to file, which in turn contains the code for the rest, and so on.
4. The program compiles (if needed) the next program, and runs it.

The final program will only print the line for Day 12. It will then exit, returning to its parent program, which will print the second line - Day 11, exit, and so on. In my example, this line will run last:

echo "and a Partridge in a pear tree"; // runs after the other twelve have run

Have fun with those quote marks. I started with PHP and Heredoc for a reason ;)

Assume that this will be run in a Linux/Unix terminal. Windows is okay if you can pull it off.

This is a popularity contest. Assuming that you can get everything escaped properly ;)

Merry Christmas!

Answer 23

A natural divisor

Expressiveness, natural language elements and readability, these are just a few of the awesome features/ideologies modern high-level languages promise us. But how "readable" and "natural" are these languages really? Can you really read them as they were english? In this challenge you have to prove how (un)natural your preferred language really is.

Challenge

You're to write a program that accepts a list/string of numbers from the STDIN, and outputs their greatest common divisor to the STDOUT. However you also need to write a complete description of your program, an english explanation of your entire program. The challenge is to make your program resemble the description as much as possible. As in a perfect natural programming language there would be no difference, your score will be the Levenshtein distance between your program and your description.

Rules

• Your description can only contain correct english sentences. The sentences must be at least six words long.
• The description must contain the full and correct process of your program. Nothing more or less. An example can be found below. As a general rule: a programmer that doesn't understand your language should completely understand your description and should be able to recreate the exact algorithm.
• Your program cannot contain both comments or strings.
• Your program should use the universal accepted definition to calculate the greatest common divisor. If the input only contains 0's, you have to output 0.

Example

This is a fibonacci function to illustrate how a description should look like:

PROGRAM:
def F(n):
    if n == 0: return 0
    elif n == 1: return 1
    else: return F(n-1)+F(n-2)

DESCRIPTION:
Define a function F with input n. If n equals 0, return 0. 
Else, if n equals 1, return 1. 
Else, return the output of F with input n minus 1, 
plus the output of F with input n minus 2.

Score

As mentioned earlier, your score is the levenshtein distance between your description and your program. You can calculate your levenshtein distance with the following snippet (thanks doorknob):

var f=document.getElementById("f"),g=document.getElementById("s"); function h(){var a=f.value,e=g.value;if(128<a.length)a="<span style='color:red'>First program is too long!</span>";else if(128<e.length)a="<span style='color:red'>Second program is too long!</span>";else{if(0===a.length)a=e.length;else if(0===e.length)a=a.length;else{var d=[],b;for(b=0;b<=e.length;b++)d[b]=[b];var c;for(c=0;c<=a.length;c++)d[0][c]=c;for(b=1;b<=e.length;b++)for(c=1;c<=a.length;c++)d[b][c]=e.charAt(b-1)===a.charAt(c-1)?d[b-1][c-1]:Math.min(d[b-1][c-1]+1,Math.min(d[b][c-1]+1,d[b-1][c]+ 1));a=d[e.length][a.length]}a="Distance = <strong>"+a+"</strong>"}document.getElementById("d").innerHTML=a}f.onkeyup=h;g.onkeyup=h;

<h3 id=ft>program</h3>
<textarea id=f rows=7 cols=80 style="width:100%"></textarea>
<h3 id=st>description</h3>
<textarea id=s rows=7 cols=80 style="width:100%"></textarea>
<p id=d></p>

Sandbox questions/notes:

• The question was just crazy idea for the most part. Do you think this question would work?
• Are there any languages that would get an unfair advantage? Are there more things I should ban?
• I know the description of the program description is somewhat subjective, so the answers would mostly involve being creative with their description. Are their any additional rules that could restrain this?

Answer 24

Final Exam Grade Calculator

So, it's around time for finals, and many students want to know what grade they need on their final exam to achieve an A, B, or sometimes a passing grade. There are many factors here - the weight of the final, two quarters having weight, what grade the students want - but it is still a simple task.

Objective

Write a program that will take three integers and output the grade they need to receive on the final.

Input

Three integers. The first two will be from 0 to 100, and the last will be from 1 to 100. They represent the current score in the class, the desired score, and the weight of the final, respectively. A working example can be found here.

Any input outside the expected ranges can have undefined behavior.

Output

The score the student needs to receive on the final exam. This score could be above 100 (every once in a while, students have unrealistic expectations), but if it is a negative number, it is automatically 0. The formula for score is as follows.

(desired - (current score * (1 - weight*.01))) * 100/weight

The output may not be an integer. In this case, round to the nearest hundredth (round up for .##5).

Examples

Input: 100 90 20    
50

Input: 65 60 30
48.33

Input: 54 100 25
238

Scoring

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

Bonuses

• -10% if your code can take either 3 or 4 integers as input. If four integers are taken, then the first two are averaged to give what would normally be the first integer. Each of the first two integers here represents a quarter grade.

What other bonuses should I add? I can't think of many right now, but even one or two more would be helpful.

Answer 25

Possible resistances from resistors

code-golf electrical-engineering

Meta: Note this is far from done; just putting this idea out so that I can continue working on it. IE way work in progress. I need to specify a lot more of this and I'm putting this here because I know I won't end up working on this if it isn't here.

Given a set of resistors, output all the possible resistances that can be formed with them.

Thoughts so far:

Input:

Input will be a comma-separated or space-separated list of natural numbers such as

1 4 3 2 4 3 5 999

Output:

Output will be all the possible formable resistances, sorted, on its own lines, plus the number of ways to form each resistance.

(no example yet)

Answer 26

Implement the Henkin quantifier

code-golf logic

Your goal is to implement the Henkin quantifier Q_H, a generalized (branching) quantifier on four variables x1,x2,y1,y2 and a Boolean function f. It expresses the idea that for every choice of the x's, there's a choice of the y's so that the four variables satisfy f, so that each y depends only on the corresponding x and not the other one.

The parallelness of the choice of is sometimes represented by stacking the paired quantifiers like this:

This quantfier cannot be expressed in first-order logic.

The parallel choices for the y's are like prisoners being interrogated in separated rooms. They are each asked the respective questions x1 or x2 and must give respective answers y1 and y2 without knowing what the other one was asked, so they are liable to be trapped in inconsistent claims. The guards then evaluate the validity of their responses ointly by some function f that depends on both questions and answers. If the prisoners can always win this game, then f satisfied the Henkin quantifer Q_H.

Formally, the Henkin quantifier Q_H takes in a Boolean function f of four inputs (x1,x2,y1,y2), and evaluates whether the following statement is True:

For every x1 there exists a y1, and for every x2 there exists a y2, so that f(x1,x2,y1,y2) is True, and the choice of y1 depends only on x1 and the choice of y2 depends only on x2.

Alternatively stated in Skolem normal form

There exists functions g1 and g2 so that for every x1 and x2, the function f(x1,x2,g1(x1),g2(x2)) is True.

For this challenge, the domain of discourse will be natural numbers from 0 to 9.

Input:

A function f that takes in four numbers x1,x2,y1,y2, each between 0 and 9 and produces a Boolean output.

Output:

A consistent Truthy value if f satisfies the Henkin quantifier Q_H, and a Falsey value if it does not.

---

Questions for Sandbox:

1. Does this challenge make any sense?

2. What should the input format be? Not every language can take in functions. What about nested lists? Subsets of four-digit numbers?

Answer 27

The Great, White, North! code-golf - POSTED

Answer 28

Solve a LaserTank level (optimally?) [WIP]

LazerTank is more than just a computer game, it is a blast from the past. In this game, the player controls a tank that shoots lasers and navigates through a series of puzzles. The goal of this challenge is to write a program that solve game levels.

TODO: Actually explain how LaserTank works. There is an instructions page on the website.

Input will be an ASCII representation of the game map. TODO: determine which characters stand for what stuff.

Output will be the list of actions required. There are four possible actions for each step in the solution, "move forward," "turn left," "turn right," and "shoot".

Answer 29

Counting k-mers

The task is to count the number of distinct substrings of length k, for k = 1,2,3,4,.....

score

Your score is the highest k you can get to on my computer in under 1 minute.

You should use http://hgdownload.cse.ucsc.edu/goldenPath/hg38/chromosomes/chr2.fa.gz as your input and ignore new lines.

You should ignore all newlines. You can preprocess the input to decompress it before starting.

The following code outputs a histogram of all the 4-mers. You can then count how many there are with wc.

awk -v substr_length=4 '(len=length($0))>=substr_length{for (i=1; (i-substr_length)<len; i++) substrs[substr($0,i,substr_length)]++}; END{for (i in substrs) print substrs[i], i}' file.txt

(This question is not finished yet.)

fastest-code

Answer 30

Elevator Control [WIP]

The controller is still a WIP, but I have a decent idea of how it'll work.

You have been hired as a Vertical Integration Specialist (programmer) at Ascension Incorporated to write advanced elevator controller software. (backstory wip)

Elevators are Cool

The current setup is that there will be ten floors and three elevators. This is 100% subject to change. I'm not exactly sure how the game will be judged, below is an idea.

As people begin queue up, your elevators will be responsible for making sure that they get where they want to go. Each game tick, there is a certain % chance that a person will queue up at a given floor with a random destination. You goal is to transport 1000 people in the least time possible.

Details

Your submission will be the the form of a Java class. This class must contain at least two methods: the constructor mySubmission(Elevator[] elevators, Floor[] floors) and update(Elevator[] elevators, Floor[] floors). The constructor class will be called once, and update after every game tick.

Elevator Class:

• int location gives the current floor location of the elevator. (Read-only)
• int dest gives the destination of the elevator. All elevators have a destination, even an idle elevator, in which case the destination is the current floor. (readOnly)
• String status is idle or busy. Elevators which are idle are not moving and have no floors in queue. (read-only)
• boolean[] buttons tells which buttons have been pushed, signifying that a person in the elevator wants to go to that floor.
• ArrayList<Integer> destQueue gives the list of destinations for this elevator. An idle elevator with something in destQueue will become busy and have a new destination. (writable)
• goToFloor(int i) adds that floor to the queue if it is not already in it.
• clearQueue() clears the queue. Simple as that.

Floor Class

• boolean waiting means that somebody is at that floor.
• boolean up means that somebody on that floor wants to go up.
• boolean down means that somebody on that floor wants to do down.