# 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.

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

## Get the Sandbox Viewer to view the sandbox more easily

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

# Find the nth positive integer m for which $$\\tan(m) > m\$$code-golfmath

Write a program/function that when given an integer $$\n\$$ as input outputs the $$\n\$$th positive integer $$\m\$$ for which $$\\tan(m) \gt m\$$.

Note: $$\m\$$ is in radians

## Scoring

This is so shortest bytes wins.

## Sample Testcases

# n -> m
1   -> 1
2   -> 260515
3   -> 37362253
5   -> 534483448
9   -> 214112296674652
10  -> 642336890023956
16  -> 4285797387061825747646013


Find more at A249836

Inspired by What is the biggest tangent of a prime?

• +1 for referencing a MegaFavNumbers video. – Razetime Aug 20 '20 at 3:24
• I don't understand the point. Are you asking us to find the nth number such that tan(x) > x? Is there any approach that will be shorter than iterating over all numbers until you find the nth number such that tan(x) > x? – the default. Aug 20 '20 at 3:33
• Where is n in the equation? I'm lost. – V. Courtois Aug 20 '20 at 9:07
• @Razetime On the channel Stand-up Maths, right? – Rosie F Aug 20 '20 at 18:49
• replace "nth" with "first" "second" etc -> "first/second/etc number m for which ..." i.e. n is not in the equation @V.Courtois – golf69 Aug 20 '20 at 20:30
• @Mukundan314 maybe indicate that n is the input? – golf69 Aug 20 '20 at 20:31
• @golf69 oh! So it has to be an integer, not a number. I see now :) And yes, indicating n is the input would be nice. – V. Courtois Aug 21 '20 at 6:50
• I don't really see this being solved any way that taking the generic golfiest code for "find the n'th number meeting [predicate]", of which there's plenty of challenges, and sticking in tan(m)>m for the predicate. – xnor Aug 22 '20 at 7:04
• Solutions relying on floating-point arithmetic will get the wrong answer starting around the 11th term. You’ll need to clarify whether that’s acceptable. – Anders Kaseorg Aug 22 '20 at 22:14

# Is it a Pythagorean triple? code-golfdecision-problemgeometrymathnumber-theory

Given three numbers, determine whether they form a primitive Pythagorean triple. Here is the definition:

• all three numbers are positive integers
• they represent the side lengths of a right-angled triangle, that is, $$\a^2 + b^2 = c^2\$$ for any ordering of $$\a\$$, $$\b\$$, and $$\c\$$
• no other primitive Pythagorean triple exists with the same ratio of side lengths, that is, they are coprime. For example, $$\[6, 8, 10]\$$ is not a primitive Pythagorean triple, even though it satisfies the above conditions, because the simper $$\[3, 4, 5]\$$ exists.

## Rules

• Unless your language doesn't support them, you must accept floating-point numbers (even though Pythagorean Triples use, by definition, integers)
• meta: Is this necessary? Is it too restrictive?
• You may be given negative numbers, $$\0\$$, or numbers that cannot form any triangle (right-angled or not, i.e. $$\a + b \le c\$$), in which cases you must return false.
• meta: Is this necessary? Does it make it too difficult?
• You can return any two distinct individual values, or any typical truthy/falsey values for your language.
• Standard I/O and loophole rules apply.
• This is , so shortest function or full program in bytes wins.

## Test Cases

[0, 3, 3] => false
[3, 4, 5] => true
[5, 3, 4] => true
[3, 4, 6] => false
[3, 4, 10] => false
[6, 8, 10] => false
[3.0, 4.0, 5.0] => true
[3.1, 4.0, 5.0] => false
[-3, -4, -5] => false
[3, 4, -5] => false
[4.5, 6, 7.5] => false
[91, 60, 109] => true
[264, 265, 23] => true
[81, 210, 184] => false
[140, 221, 83] => false


## Meta

• Are the first two rules necessary, or do they restrict it too much?
• Is it clear enough? Are there any additional rules I need to add? Are more test cases needed?
• Does this suit the and tags? It's kind of tangential to both areas.
• Is this too similar to the existing questions that want you to generate triples?
• possible duplicate of this challenge – Razetime Oct 18 '20 at 13:38
• @Razetime that challenge appeared on the front page today and inspired me to make this one. I thought it was different enough because of the coprime requirement and I added the extra rules about invalid values/floats to make it more interesting as well – pxeger Oct 18 '20 at 14:32
• Input validation tends to make for a challenge that is less fun. The coprime requirement is nice, but I'm not sure if it completely changes the challenge. – Razetime Oct 18 '20 at 15:04
• This seems to me to be too much a combination of two separate generic tasks, checking that a^2+b^2=c^2 when sorted, and that a and b are relatively prime. – xnor Oct 19 '20 at 9:40

# Am I A Perfect Two Integer?

A “perfect two integer” is an integer that works as x in the following equations:

Let i = integer, j = integer, x = perfect two integer:
2^i = x
j^2 = x


Example “perfect two integers”: 4, 16, 64, 256, 1024 (see a pattern here?)

Your answer should take a number from stdin or an argument. This should be relatively easy, but this is , so the shortest answer wins. (Note: there are ways to simplify these equations that aren’t listed here).

## Sandbox Questions:

1. Is this a duplicate?
2. Is this too easy?
3. Any other thoughts?
• My personal feeling is that this is too easy. There's not really much scope for golfing the answer once you find the pattern. – Sisyphus Oct 28 '20 at 0:25
• Yeah, you're probably right. It's kind of just like if it's a power of 4. I somehow didn't think about this while making the question. – nthnchu Oct 28 '20 at 0:34

# Is it metal or non-metal?

Write a program/function getting as an input/argument symbol of a chemical element and printing/returning 1 if it is metal and 0 if it is non-metal. It is up to you/your language what to do if the symbol is invalid. E.g. call an error or print "Error" or something.

# Testcases

Na ⇒ 1
S ⇒ 0
FFF ⇒ error/unidentified behavior/etc.
F ⇒ 0
Fe ⇒ 1


# Rules

• "FFF ⇒ error" - must we output an error, or can it just be undefined behaviour? Challenges tend to be a lot more interesting if we don't have to do input validation. – pxeger Dec 24 '20 at 7:23
• Also what are we doing about metalloids? – pxeger Dec 24 '20 at 7:26
• @pxeger ok I'll edit question. – Victor VosMottor Dec 24 '20 at 9:48
• @pxeger Yeah I know about it. Sorry I didn't remember when I was creating the challenge 'cause in Russian chemistry we are trying to split elements to two groups AFAIK (maybe I'm wrong). – Victor VosMottor Dec 24 '20 at 9:50
• You should probably attach a list of all elements which should return 1, to prevent ambiguity. Also maybe you can add the tag [kolmogorov-complexity] – Command Master Dec 29 '20 at 7:53

Find out if a function returns its input.

# Input Format

Input is a math expression as a string with operators + - * /. Whitespace can be ignored. For more info, check the examples.

# Example Input/Output

Input: n /3 + 2*n/3 + 175 - 175x(n+ 1-n)
Output: true
Explain: Simplifies to "n".

Input: f
Output: true
Explain: Any variable is allowed.

Input: j*(j-3)/(j-   3)
Output: false
Explain: When j is 3, evaluates to an error.

Input: 1j
Output: anything or error
Explain: Use "1*j".


# Scoring

This is , so lowest amount of bytes wins!

## Sandbox Questions

I posted because of reputation limit, but was too unclear, any suggestions please?

• There's some inconsistency in the examples: the first one is being treated as if it's a maths expression whereas the third one is not. Suppose the input is n/2 + n/2. Should the output be true? In some languages the output will not necessarily be the same as the input: / might get you floor division or conversion to a float. You can avoid these issues by treating the input as maths. But in that case, example 3 should simplify to j. – Dingus Jan 5 at 9:38

# KoTH: Solve a maze (WIP) king-of-the-hillscala

In this challenge, you and your opponent compete to get to the middle of the maze first.

### Possible moves each turn:

• Move one cell left, right, up, or down. If you attempt to move to a cell that is outside the maze, that is occupied by a wall or the enemy, or is more than one cell away from you (Manhattan distance), nothing happens.
• Build a wall at a given coordinate. If the coordinate is outside the maze, there is already a wall at that coordinate, or your opponent is at that coordinate, nothing happens.
• Break a wall that is one cell left of, right of, above, or below you.

You can use either an object or a lambda to implement the following interface:

trait Bot {
def nextMove(
yourPosition: Pos,                    //Your position
enemyPosition: Option[Pos],
visibleCells: Map[Position, String]): Move = {
}
}


where Pos and Move are defined as such:

case class Pos(x: Int, y: Int)

sealed trait Move
case class Walk(to: Pos)
case class BuildWall(pos: Pos)
case class BreakWall(pos: Pos)


ScalaFiddle link coming soon.

# Questions for Meta:

• Instead of reaching the center of a maze, perhaps both bots could look for a moving target? Then a possible strategy would be to trap/delay your opponent and then take your time trying to find the target.
• Should I make walls take 2 or 5 or X hits to break?
• Where should the bots start relative to each other? Opposite corners, right next to each other? I'm leaning towards the latter right now.
• To get a sense of how many people will actually do this challenge, could you upvote this comment if you think you will write an answer to it? I want to make sure I don't waste a ton of my time writing a question no one answers. – user Jan 5 at 14:16
• I don't see any strategy better than "go straight to the middle and break everything in the way"...if both bots start the same distance from the middle, they could never really interact unless one was already sufficiently ahead to block the other one off. – Redwolf Programs Jan 5 at 14:36
• @RedwolfPrograms Hmm, how about requiring 2 hits when breaking a wall, thus making it more advantageous to find a path and to block your enemy? – user Jan 5 at 14:38
• I won't be able to participate because I don't know Scala. Is there really any reason to place walls? (if you're placing a wall, then either the opponent won't encounter it, or you're already ahead) Can we only build walls adjacent to us? (the question doesn't mention that) If breaking a wall takes 2 turns, it's still almost pointless to avoid walls. – the default. Jan 5 at 14:40
• @user That's sort of what I was thinking, yeah. The strategy would also probably depend on the initial arena and where the bots start relative to each other. – Redwolf Programs Jan 5 at 14:44
• @thedefault. Even if you're ahead, you may get stuck at a wall and your opponent may find an alternate path. Or maybe you just randomly create walls to maybe get your opponent stuck. And yeah, you can build walls anywhere. – user Jan 5 at 14:44
• @user Then you can easily prevent the opponent from advancing. It takes 1 turn to block any cell and 2 turns to unblock it. (so simply blocking the opponent's shortest path is sufficient) – the default. Jan 5 at 14:51
• @thedefault. I suppose so, if you can find the opponent. Any ideas on their starting positions, so they have a chance to block each other, but the first bot doesn't just immediately trap the other? – user Jan 5 at 14:54

# Every number is interesting

We know that every number is interesting but how?

You should write a program or function which:

• takes a list of N positive integers (>0 and <2^31)
• outputs N lines each of them showing how the corresponding input number is interesting
• is not longer than 1024 bytes
• uses no more than 1 second per number
• doesn't use external sources

## Examples

172: 444 in base6
5776: 76*76
9801: 9 * 1089 (reverse)
68101: no 11 in base2 (10000101000000101)
491033: 317 * 1549 (product of 2 big primes)
467808816: no digit 5 from base6 to base10


## Inputs

You should include the output for the following input in your post:

58 92 120 224 358 490 912 1578 7812 222008 1645060 19796411 550453633


If you care to run your program on a bigger sample and share the result with us use this input data (2500 numbers). (You can upload your output to e.g. pastebin.)

This is a popularity-contest so highest voted answer wins.

Tags: popularity-contest, number

• What sort of criteria are necessary for defining a number as 'interesting'? I see things like square numbers, other bases, etc. But are there any specifics? I'm interested in this challenge (but worried it might be closed as too broad). – ASCIIThenANSI Apr 7 '15 at 13:18
• @ASCIIThenANSI There wasn't a clear definition. That's part of the reason why I abandoned the challenge. – randomra Apr 8 '15 at 1:55
• Would you mind if I tried taking it up? I would have to post as a new answer, because I can't directly edit. – ASCIIThenANSI Apr 8 '15 at 2:00
• @ASCIIThenANSI Not at all. – randomra Apr 8 '15 at 2:01
• @ASCIIThenANSI Where did you post it? – wizzwizz4 Jul 24 '19 at 13:33
• @ASCIIThenANSI I am also curious – MilkyWay90 Aug 27 '19 at 23:41

# Create a Drawing Guide for a Polygram

Poor old Jim, he's just terrible at drawing polygrams, and he's asked you to create a "drawing guide" for him - an ascii polygram with numbered edges, so he can follow the instructions.

## Challenge

Write a program to produce an ascii polygram with P <= 10; each edge of the polygram should be made of a single digit 0-9, showing the order in which the edges should be drawn.

## Input

Your program should receive (via STDIN, as function arguments, or some other language-appropriate method): P, the number of edges/vertices of the polygram, and Q, the spacing. In the notation as per the Wikipedia link, you'll be drawing a {p/q} polygram.

## Output

Either print to STDOUT or return (or something else language-appropriate) a multiline string showing the drawing guide for the given polygram. The string can be any size you like, as long as it's large enough to display a clear polygram.

## Notes

Your code should be able to handle compound regular polygons as well as regular regular polygons, and also inputs of q > p/2 (poor old Jim doesn't realize that the polygram for {p/q} is the same as for {p/p-q}).

## Example Output for {10,3}

              5
5 4
4
21     5        888
2 11115     8888  7
2    5111888 4    7
2     888111  4   7
2  888      111   7
8885           4117
8882               4 711
8   2 5               7  111
25               47
9   5                 7    0
9  2                 74  0
52                 7  0
9 2                 7 4
5 92                 7 04
9                 70  4
5   2                 7
5    29                7    4
6666 2 9              07   33
666              0 7333
2 696           337
2   9666     333  7
2    9  66633 0   7
2      333 666    7
2   339       666 7
2333   9    0    67
9  0
0


## Scoring

This is code-golf, so shortest in bytes wins. Tiebreaker goes to the most votes.

• I have a python solution to this which is ~600 bytes, so it's definitely doable, and it's not easy... – sirpercival Apr 27 '15 at 4:31
• I think the spec needs to be more prescriptive for this to make a good question, especially since the example seems to indicate that you're not currently even prohibiting the lines from having gaps. At a minimum I would say that you should require the lines to be equivalent to those produced by Bresenham's algorithm, and specify how overlaps should be handled; at the extreme, you could tie it down so tightly that it becomes a parameterised kolmogorov-complexity. – Peter Taylor Apr 27 '15 at 9:34

# Pointer to pointers to pointers to pointers

You should choose a language supporting pointers like C. And your task is simple: demonstrate a legitimate use of the most level of pointers.

You should justify your code by describing an algorithm that:

• Has only plain text, number or an array of those as input and output.
• You think it will make things easier to write those code as a part of the implementation of this algorithm.
• This implementation would have optimum memory usage (only declared variables and parameters, explicitly allocated space, and the return addresses for recursive functions count).

Other rules:

• They must be pointers to pointers directly, i.e. a pointer to an object containing a pointer doesn't count. It's better if nobody using this code will want to extend some pointer to an object later.
• Each pointer must have a different type (if your language can somehow make them the same type).
• You should create at least one pointer, and either dereference or compare two non-null pointers once in each level.
• Using pointers as arrays is only half as interesting.
• Iterators, etc, are considered in essence pointers and allowed in this challenge. But you can't define new types implementing iterators for this purpose.

• Could you specify "legitimate"? This sounds a bit like code bowling (and seems to have the same issues). With enough imagination I'm sure I can justify any depth of pointers. – Martin Ender Apr 30 '15 at 17:43
• @MartinBüttner Edited but, basically, it is subjective. – jimmy23013 Apr 30 '15 at 17:57
• @MartinBüttner Added a restriction to have optimum memory usage. I'm not sure whether it works. – jimmy23013 Apr 30 '15 at 18:19

# Winning Tic-Tac-Toe lines

For a given tic-tac-toe board of size N**D (for example, a normal tic-tac-toe game is 3**2), the number of winning lines of length N is given by the expression:

$$2^{D-1} + \sum_{S=1}^{D-1}2^{S-1}DN^{D-S}$$

(Basically, you are summing the number of lines in each S-dimensional slice of the board.)

# The challenge:

Given N and D, your answer should output a list of D-dimensional coordinates for each winning line. Input and output are any reasonable format. You can assume that both N and D are positive integers, with N > 1. (Degenerate cases of N=1, D>1 not included.)

Since this is , fastest answer wins. Please explain your algorithm!

• How do you intend to determine which of two answers is fastest? – Peter Taylor May 12 '15 at 19:37
• yes, @randomra made the same point on chat. i'll edit this in, but i guess... i'll put together some test cases and then time them? i dunno, i was going back and forth between this and code-golf, but i'd prefer interesting and readable algorithms. – sirpercival May 12 '15 at 20:10
• i posted this here because i really want the answer, and i hate coming up with brute force solutions... :D – sirpercival May 12 '15 at 20:16
• Um. Given that you're asking people to enumerate an exponentially large set, in what sense will the answers not be brute force? – Peter Taylor May 12 '15 at 20:28
• well, there's brute force and then there's brute force. but really it's because i don't want to do it myself, haha. – sirpercival May 12 '15 at 20:34
• also, making use of symmetry can severely reduce the computation. – sirpercival May 12 '15 at 20:40
• I imagine that the runtime in any such algorithm will be basically proportional to the number of things you print, so there won't be any good way to improve by algorithm and the speed will be very platform-dependent. – xnor May 12 '15 at 23:40

# Ayn Random number generator

Inspired by xkcd 1277:

Write a random number generator that takes no input and generates a random integer between 1 and 100. When run less than 200 times, the frequency of all numbers needs to be between 0 and 2, but when it's ran 50 000 times, the number 42 (obviously) should have a frequence that's more than 4 standard deviations higher than the mean.

Format is code-golf. Your score is the bytecount of your code.

• 1. I think it's difficult to decide objectively whether a PRNG appears to be fair at first sight. 2. The term more often should probably be quantified. – Dennis May 18 '15 at 21:49
• I see lots of C rand()%1000 and the like incoming... – rorlork May 18 '15 at 22:05
• @Ypnypn I have changed the criteria to have much lower numbers so they're easier to verify. – Nzall Jun 6 '15 at 13:04
• @Dennis I have rewritten the question to clarify what "being fair" is and what "more often" actually entails. – Nzall Jun 6 '15 at 13:05
• 1. Are you thinking of a standalone program that you run multiple times or a function that is allowed to keep a state? In the first case, not even a perfect RNG will, with overwhelming probability, satisfy the first condition. 2. Do you mean the mean and standard deviation of a perfect, uniform RNG or the one the code implements? – Dennis Jun 6 '15 at 23:44
• @Dennis I'm thinking of just a function AynRandom() that gets called. The frequency of numbers with a small number of iterations is subject to change, maybe from 0 to 4. The mean and Standard Deviation must be the one the code implements. – Nzall Jun 7 '15 at 9:49
• between 0 and 2 ? so print 42 would be a valid program ? – Falco Jun 11 '15 at 15:32
• @Falco No, because 42 would appear more than 2 times (unless you only run it twice). The problem is that I need a way to indicate that the RNG is fair with a low iteration count, but unfair with higher iteration counts. The only way I can make it work is by stating that with low iteration counts, all numbers should appear about equally often, which is either 0, 1 or 2 times. – Nzall Jun 11 '15 at 15:36

Please nitpick this. If there's anything that wouldn't work or would be inconvenient, however small of an issue it is, tell me about it!
Also, suggestions for [adjective] are more than welcome.

# Determine how [adjective] a number is (code-golf)

A number would be considered [adjective] if 0 is the result of multiplying its digits together, then multiplying the digits of the resulting number, then repeating until a single-digit number is produced. The more steps it takes to reach 0, the more [adjective] the number is; if the resulting number is not 0, though, the number is not [adjective] regardless of how long it took to finish.
The formula used to determine [adjective]-ness is 10-10/T where T is however many numbers it took to reach 0 (including 0 and the initial input)

Your goal is, as the title says, to write a program or function that determines how [adjective] a number is, and prints every iteration along the way. Here are some example inputs/ouputs:

in: 879
out: 879    <-       (T=1)
504    <- 8*7*9 (T=2)
0      <- 5*0*4 (T=3)
<- optional newline
6.6... <- 10-10/3 (repeating decimals can be expressed in any way you want)

in: 2468
out: 2468   <-  T=1
96     <- (T=2) 2*4*6*8
54     <- (T=3) 9*6
20     <- (T=4) 5*4
0      <- (T=5) 2*0

8      <- 10-10/5

in: -888
out: -888
-512   <- -8*-8*-8
-10    <- -5*-1*-2
0      <- -1*0

6.6... <- 10-10/3

in: 1344
out: 1344
48
32
6

0    <- did not produce 0, so the prog/func returns 0


-Takes input from STDIN.
-Throws an "error" (printed to STDOUT) and halts immediately after input if the input has one or more 0s in it or if it's less than three digits in length. The error must be a string, and as it's supposed to be printed to stdout, cannot be one generated by the language itself (eg 1/int(min(input())) to check if it's zero). Lastly, the error message has to clearly define what the error is; ERR:0 and ERR:LEN, for example, would suffice.

Bonuses/Penalties:

-25 if it properly handles decimals. For instance, an input of 99.22 would first turn into 9*9 + 0.(2*2), or 9*9 + 0.4, and so on.

This is , so the shortest answer in bytes wins.

• I don't like the +15 penalty. Whether strings are used is vague in some languages. The constant amount +15 is too little deterrent for some languages but huge for very concise ones. The fact that you've found a short solution you don't like is sign you should rethink the problem, not try to plug the hole. – xnor Jun 17 '15 at 7:48
• @xnor that's reasonable. I suppose it is a valid way of doing it, anyway, so I removed all mention of strings in that section. Should I also inc/decrease the bonus for decimals? – hallo Jun 17 '15 at 22:29
• The programming languages I know either don't allow throwing user-defined errors or print them to STDERR. Now, if you just want us to print a message and exit immediately... – Dennis Jun 17 '15 at 23:32
• ...and should be printed to STDOUT. I had a feeling that wasn't clear; I edited it, is it better now? – hallo Jun 17 '15 at 23:33
• It's the word throw that throws me off (no pun intended). To throw an error usually means something rather specific. Print an error message to STDOUT (or closest alternative) would be less confusing in my opinion. Also, since this is code golf, I think you should require specific error messages. There's no fun in losing a contest because you chose ERR:LEN and somebody else got away with EL. – Dennis Jun 18 '15 at 3:16
• Remove bonuses altogether. It's in the list of things to avoid. – mbomb007 Mar 1 '16 at 21:31
• The error if the input contains a zero seems like a separate challenge. It may be better received if there is only one challenge. There is community support for avoiding Chameleon challenges. – trichoplax Aug 10 '16 at 11:40

# Represent a Number in the Strangest Way You Can Think Of.. while staying under 8 unique characters

Your goal is to represent some numbers in the strangest way possible.

### Rules:

• The result must be a number that can be used in the programming language like any other ordinary number. For instance, <my expression> + 3 should return 3 more than the value of <my expression>.
• The code must be under 20 kilobytes. That's a rather large size for a number so you should be all set.
• The expression must have under 8 unique characters! The length of it can be as long you want, just keep it under 8 unique characters. aaaaaaaaaaaaaaaaaa is valid (if it works in the programming language) but abcdefghijklm isn't valid because it uses 8 or more unique characters.

### Guidelines:

• The goal here is to represent a number in the strangest and most interesting way possible, so if I ask you to represent the number 35 it would be a good idea to respond with something more interesting than 35 or 12 + 23.
• This isn't a ! Feel free to make your code as long as you want, so long as it's under 20 kilobytes. Fancy code can look nice!
• The code doesn't need to support decimals (floats) but if it does, it will get 10 extra points (see below).
• The code also doesn't need to support negative numbers (for instance -37) but if it does, it will get 10 extra points (see below).
• Try to make your post follow the below:

# Language

Description

### 0

...


### 1

...


### 30

...


### 108

...


### 1337

...


### 1234567890

...


### 3.1415 [10 bonus points if you can get this!]

...


### -25 [10 bonus points if you can get this!]

...


## Bonus numbers:

...

The points is equivalent to the number of votes on the answer plus 10 if it supports decimals with 10 more points if it supports negative numbers. Whoever has the highest points is considered the current winner. Have fun!

This is my first go at making a popularity contest so if you have any tips those would be appreciated.. :)

• This is a great challenge... whoever downvoted this has to rethink their concept of code-restriction challenges... – WallyWest Jul 15 '15 at 22:49
• Ah, thank you. :) – Florrie Jul 15 '15 at 23:28
• Updated again with negative numbers added (-25), as well as 1 and 0. – Florrie Jul 15 '15 at 23:33
• @Sp3000 8 unique chars, not 8 total. – isaacg Jul 16 '15 at 10:04
• @isaacg Didn't I state that? – Florrie Jul 16 '15 at 11:11
• @liam_ You did, the person I was responding to who deleted their comment missed it. – isaacg Jul 16 '15 at 11:32
• TBH, I think this is such a poor popcon that it can't be rescued, but if you want to at least make it clear what you're asking then: 1. You talk about representing "a" number, but also about "support[ing] decimals" and "support[ing] negative numbers". What exactly do you want? A function which maps numbers to code? But if so, the "Post format" makes no sense. 2. What is the code which has a 20kB limitation? Total for all the numbers listed in the "Post format"? Each individual number listed in the "Post format"? Something else? 3. Are the 8 distinct characters per number or for all numbers? – Peter Taylor Jul 17 '15 at 16:19

# Wrong tool for the task

Write two full programs in the same programming language that solve the following two tasks:

1. Read two positive integers from STDIN and print their sum to STDOUT.

2. Read two positive integers from STDIN and print their product to STDOUT.

• Given enough time and memory, your programs has to support arbitrarily large integers.

• All integers (input and output) use standard decimal notation, have no leading zeroes and are followed by a single linefeed.

### Scoring

The first task is code golf, so your objective is to make your program as short as possible.

The second task is code bowling, so your objective is to make your program as long as possible.

Your score is defined as follows:

The highest score wins!

### Robbing a language

There's a catch! Only the submission with the shortest program in a particular language will be considered valid for task 2, so there can only be one valid answer per language.

This means that you cannot deliberately write a huge program for task 2; you actually have to pick the "wrong tool" for the task.

• Task 1 exists merely to provide the proper denominator for the score (and robbers have no moral anyway), so byte-per-byte copies of somebody's program for task 1 are allowed.

• If two answers use the same language and have programs of the same length for task 2, the answer that achieved that length first will be considered valid.

• If somebody invalidated your answer, you may attempt to golf your answer to revalidate yours and invalidate his.

• I suspect this will come down to people writing code in unary and disagreeing on what input/outputs formats are valid for such a language. – xnor Jul 20 '15 at 20:17
• @xnor I'm not sure I understood your comment. The format for I/O is purposedly restrictive, so an answer's validity should be clear-cut. – Dennis Jul 20 '15 at 20:25
• @feersum I think the log scoring does benefits unary. Say (making up numbers) task 1 takes 100 chars of BF and task2 takes 150 chars. Then, those are translated to 300 chars and 450 chars of binary, and so 2^(300) and 2^(450) chars of unary, giving a score of 1.5. In comparison, if the tasks take 20 chars and 50 chars in another language, that's about a score of 1.3. I guess this is surmountable though (20 and 100 gives 1.5). – xnor Jul 20 '15 at 20:33
• Are the inputs decimal numbers? For a language like BF, can the numbers be taken as byte values rather than characters? What separator should be used between the numbers? Are leading zeroes OK in the output? I think you'll have to be pedantic and precise about everything given how much of the character count may depend on details, but it's doable. – xnor Jul 20 '15 at 20:35
• Yeah that's right, it is only for Unary. – feersum Jul 20 '15 at 20:37
• @xnor All integers (input and output) use standard decimal notation, have no leading zeroes and are followed by a single linefeed. – Dennis Jul 20 '15 at 20:42
• @Dennis Wow, you anticipated everything and I missed it. I take it then that input must be as a string of numerical characters? Also, do I understand right that you have to print a newline for output (say, print a+b,"\n" in Python)?. – xnor Jul 20 '15 at 20:45
• @xnor Yes to both. The newline is required and you have to use numerical characters. I'd specify the exact character range, but I don't want to exclude non-ASCII languages.I'll think of a way to make it clearer. – Dennis Jul 20 '15 at 20:51

# GitHub Gist command-line client

Create a command-line tool that publishes a list of files as one public GitHub Gist.

## Specification

The following bullet points describe the behavior of the program. If a bullet point has "must", you must implement that point. If a bullet point has "can optionally" or "should optionally" you can implement that point on your own volition.

1. It must be a complete command-line program.
2. It must use the GitHub Gists API.
3. It must post an anonymous Gist (that is, not as a GitHub user).
4. Gisted files must use the filename provided on the command-line.
5. The command-line must accept multiple positional arguments.
6. If no arguments are specified, it must print this usage to STDOUT: gist: usage: <file> [file...] verbatim then exit with code 0.
7. If something else goes wrong, it must print this message to STDERR: gist: unable to gist =( verbatim then exit with code 1.
8. If everything is successful it must print the Gist's HTML URL to STDOUT.
9. It can optionally accept a flag for description -d <description. floor(score * .9)
10. It can optionally accept a flag for private gisting -p. floor(score * .9)
11. In the case that a description flag is not used or implemented it must set the description to an empty string.

## Example Input/Output

The number before the prompt is the exit code of the previous command.

0 $gist gist: usage: <file> [file...] 0$ gist no-such-file.txt
gist: unable to gist =(
1 $gist hello.txt https://gist.github.com/anonymous/1e645596ce7bceeb1ec9 0$


## Scoring

This is a so shortest answer wins. As stated above, the following multipliers are in effect:

• (9): score = floor(score * .9)
• (10): score = floor(score * .9)
• Both (9) & (10): score = floor(floor(score * .9) *.9)
• What's up with the Example Input/Output code snippet? The editor's preview displays it correctly. – Winny Jul 27 '15 at 20:17
• For the usage, should those literal strings be used regardless of the name and invocation of the program, or should it substitute the correct invocation for the leading gist? I'm thinking particularly of cases like Java, which doesn't support hashbangs. – Peter Taylor Jul 27 '15 at 20:32
• Literal string, I think. – Winny Jul 27 '15 at 20:34
• That's a good point about Java. I think I'll remove the item about shebangs since it's unfair. – Winny Jul 27 '15 at 20:41
• If both bonuses are done, is it floor(score * .9 * .9), or floor(floor(score * .9) * .9)? – Maltysen Jul 27 '15 at 23:48
• Also, if the bonuses are done, do we have to make the usage string reflect that, or just print it verbatim? – Maltysen Jul 27 '15 at 23:50
• Output strings verbatim. And floor(floor(score * .9) * .9) for both. I'll update the question momentarily. – Winny Jul 28 '15 at 2:07
• I'm curious why this challenge is being downvoted. – Winny Jul 28 '15 at 2:28

# Golf these arrays

Your task is to output these 128 arrays: http://pastebin.com/UeBMJfv7

Gzip base64: (too long, will be added if I'll post this question).

## Rules

• You don't have to output them all. And you can output the arrays in any order. But the order of items in the arrays must be kept as is.
• You can print other arrays, which wouldn't be counted towards your score. The number of arrays you print must be no more than 10,000, and the total number of arrays, subarrays and numbers must be no more than 10,000,000.
• You can use any convenient format to represent the arrays (and the list of outputted arrays).

## Scoring

If your program or function has n bytes, and it printed k distinct arrays from the above list, your score would be n*(128/k)2. Lowest score wins.

### Problems

It looks too boring.

• It also looks too broad. – Peter Taylor Aug 8 '15 at 7:55

## The Perfect Keyboard

Back in the 1970s, keyboard designers respected the needs of programmers and languages. For example, see the IBM 2741 keyboard, designed for APL (from Wikipedia):

Today, sadly, most code golfers are forced to struggle with standard keyboards, which are badly suited to the needs of their language. This has to change!

## The challenge

1. Choose a programming language.
2. Design a keyboard, which would best suit the needs of a developer (or specifically a code golfer) in said language.
3. Post the keyboard layout as an answer.
4. Explain how your keyboard enhances the programming experience.
5. Start counting votes for 7 days, until I acceopt the winning answer (the answer with most votes).
6. Optional - if you are the winner, start a Kickstarter project to build the thing.

This section is, of course, for the sandbox only.

I don't really expect a keyboard design which would actually improve functionality of programs in an actual serious language. I'd expect fun answers, where the keyboard design highlights soemthing fun/interesting/absurd about the language. But my expectations don't matter so much, because it's not me rating the answers, but the other users.

Example (not very good ones):

1. A Brainfuck keyboard with only 4 keys.
2. A Lisp keyboard where half the keys are parentheses.
3. A Piet keyboard - I'm sure someone will come up with something nice.

• I'm note sure if it's a valid challenge since there is no programming actually involved in answering this – Fatalize Sep 3 '15 at 9:28
• @Fatalize, You're right, but it is a programming-related challenge. It requires knowledge of programming languages and people may find it interesting or amusing. I may be pushing the boundaries, I don't know. – ugoren Sep 3 '15 at 9:45
• I would personally be ok with that challenge but I don't know if other, more prominent users would find this challenge off-topic. – Fatalize Sep 3 '15 at 9:48
• Judging from this Meta post, there seems to be a fairly clear consensus that a question must involve programming to be on topic, not merely be programming related. So this question is fairly clearly not valid. – isaacg Sep 3 '15 at 10:08
• You could always include programming the driver or some kind of special interface for the keyboard – Beta Decay Sep 3 '15 at 10:28
• @BetaDecay, This challenge is about crazy creative answers. Requiring a driver implementation seems to me like a way to kill this creativity. – ugoren Sep 3 '15 at 11:01
• @isaacg, trichoplax writes "I judge it by whether the answers to it demonstrate skill and determination, or just aesthetic style" - I think a good answer to this challenge requires undestdanding a language and designing something that relates to its properties. Does it qualify as "skill and determination"? I can't say I'm sure. – ugoren Sep 3 '15 at 11:06
• The art/programming debate was specifically about popcon questions where the answers were programs. There's no doubt whatsoever that a popcon where the answers are just images would be an art question rather than a programming question. On the same basis, this is not a programming question, and does not belong on this site. – Peter Taylor Sep 4 '15 at 13:58
• @PeterTaylor - I don't think it's an art question. The challenge isn't to get a pretty picture of a keyboard, but to design something that suits the language in an interesting way. But I posted it here to get the communities opinion, and it seems quite clear what it is. – ugoren Sep 5 '15 at 19:00
• Since I wrote that meta answer the rules on popularity contests have been tightened up, and I think that is a good thing. I stand by my answer, but I think it is right that popularity contests be judged strictly, to reflect the fact that it is very difficult to write one that is a good fit for the site. – trichoplax Sep 4 '16 at 11:56
• Although it's possible someone will come up with an ingenious approach to designing a keyboard, the challenge itself seems to lean towards "make me laugh" rather than "impress me". This is why I don't think this is a good fit for the site. – trichoplax Sep 4 '16 at 12:03
• I'd love to see what keyboards the community comes up with, but I think it would need to be hosted somewhere other than main. For things which are appealing to the PPCG community, but not quite a fit for main, there's Code Golf Chat. People often post "mini challenges" which aren't well specified enough to be challenges on main, but can end up inspiring people to write a full challenge. – trichoplax Sep 4 '16 at 12:06
• I think it's important to keep testing the boundaries of existing winning criteria, and to try to come up with new ones. The people who put the effort into this will have a long run of rejections, but I really hope these don't come across as "don't try". – trichoplax Sep 4 '16 at 12:19

# Technologic - Now what's THAT command do??

Daft Punk's song "Technologic" is all about actions that a user or computer does when it's working and being used. You goal is to write a program that has one command we will call the Technologic Command. This command will executes all of the actions like "buy it", "lock it", "code it", and "write it" in the order the lyrics are written on 'it'. What 'it' is is up to you, but you gotta let me know.

# Rules

• Any language can be used.
• The song refers to an 'it'. That can be a block a memory, algorithm, function, file, or anything else a computer can manipulate directly or indirectly.
• You must specify what 'it' is you will be performing these actions on. If you don't, you can only earn a maximum of 160 points.
• Points will be deducted otherwise if a command is not used.
• I'm not aware of any 'buy' command, method, function, subroutine or instruction so use a thesaurus and find the closest word you can actually program. I don't expect the program to actually buy or snap anything. Other words like mail and fax are possible, but not recommended.
• If you have to use a synonym, you are not allowed to use that command again
• Encompassing multiple objects into one artifact does not count. For example, taking the command "name it" literally means you won't be able to name an array of bytes, but you can name a file. Creating an object that holds both a file and an array of bytes is not allowed. That would make this too easy to get the maximum amount of points.

# Scoring

• There are 16 commands with a total possible score of 190 points.
• 10 points for executing a command on the specified 'it' of your choosing (160 total)
• 2 points for executing each command consecutively that references your 'it' (30 total)
• 5 points for executing a command on something other than your 'it'
• -3 points for every command skipped.

# Command List

lyrics

Buy it, use it, break it, fix it,
Trash it, change it, mail - upgrade it,
Charge it, point it, zoom it, press it,
Snap it, work it, quick - erase it,
Write it, cut it, paste it, save it,
Load it, check it, quick - rewrite it,
Plug it, play it, burn it, rip it,
Drag and drop it, zip - unzip it,
Lock it, fill it, call it, find it,
View it, code it, jam - unlock it,
Surf it, scroll it, pause it, click it,
Cross it, crack it, switch - update it,
Name it, rate it, tune it, print it,
Scan it, send it, fax - rename it,
Touch it, bring it, pay it, watch it,
Turn it, leave it, start - format it.

• This conversation has been moved to chat. – Dennis Sep 17 '15 at 21:06
• I count way more than 16 commands here. There are 16 lines each with several commands on them. If we cound the hyphenated commands as two, there are 16 x 4 = 64 commands. – Level River St Sep 22 '15 at 22:01
• @steveverrill A slight oversight. haha. I must've counted the lines knowing there were 4 commands on each line and didn't multiply the two together. – Luminous Sep 23 '15 at 12:31

# Just Golf 2016 code-golfkolmogorov-complexity

(Related: A Kingdom Hearts VGM challenge) Sandbox note: potential duplicate?

Just Dance 2016 is coming out soon, and I know I'm definitely excited! However, let's take a quick trip back to 2009, when the original Just Dance was released. There are a lot of great songs, but I don't know who sung half of them!

## The Challenge

Write a program that accepts a Just Dance song name from input and outputs the song's artist (as credited in-game.)

Here is the list of all songs and artists from Just Dance 1:
list pending

## Rules and Assumptions

• You may assume that the song will always be valid.
• The song's title and artist must be properly capitalized.
• You may not read any external files - the song data must be hardcoded.
• If a song is covered (which several have been for various reasons), the program should return the cover artist (as they are credited in the game.)

## Test Cases

Input: Eye of the Tiger
Output: Survivor

Input: Fame
Output: Irene Cara

## Bonuses

• Each game has had one song everyone was really excited about. This year, it's Ievan Polkka by Hatsune Miku. You get a bonus of -50 points if you accept this song as valid input.

• Just Dance is fun, but why should we stop there? If you additionally accept songs fron the rest of the main series (Just Dance 2, 3, Greatest Hits/Best Of, 4, 2014, and 2015, not including DLC and skipping over any duplicates), you get a whopping -2009 points. Here is the full list for those games:
list pending

• Note that this doesn't include Just Dance 2016 songs.
• This can be combined with the other bonus to get a total of -2059 bytes.

## Meta Questions

• Are the bonuses too big? (I'm mainly talking about the -2009 point bonus for including every song.)
• Has anything been left out?
• Is this enough of a challenge?
• This looks like a dupe of codegolf.stackexchange.com/q/53678/194 . – Peter Taylor Sep 24 '15 at 20:24
• @PeterTaylor I would say it isn't, that one asks for input in the form of a game and boss and returns a song, mine asks for a song and returns an artist. That one also has different scoring rules, and mine requires all items to be implemented. – ASCIIThenANSI Sep 25 '15 at 13:51
• They're both "golf this given map / dictionary / associative array". Why would the techniques used be any different? – Peter Taylor Sep 25 '15 at 15:22
• @PeterTaylor According to this meta post, the main qualification for duplicates is "Can answers from one question be copied over to the other with little or no modification and still be competitive?". I looked at the answers for the question you linked, and it doesn't seem like either would do very well if those techniques were used in this challenge. – ASCIIThenANSI Sep 25 '15 at 15:35
• Would this be kolmogorov-complexity? – LegionMammal978 Sep 26 '15 at 17:16
• @LegionMammal978 Yes. – ASCIIThenANSI Sep 27 '15 at 14:48

# Restricted "Hello, World!"

The task is very simple, output Hello, World! to STDOUT. The thing that makes this different are the rules:

• You need to provide a full functioning program, taking no input and outputting via STDOUT.
• The program must not write anything to STDERR
• The maximum amount of bytes you can use is 50
• The program may only contain printable ASCII characters. Programs using CP437 and other encoding systems are not allowed
• If a programming language is already used, you cannot use this same language again.
• You cannot use any character of the prohibited character list. This is the twist:

### Prohibited character list (PCL):

The prohibited character list is a list full of characters, which cannot be used in the following programs. For example:

If the list was: He\., you need to create a program, without the characters H, e, \ and .. These are not case-sensitive.

If you succesfully manage to write a program that doesn't use any characters, you may add new one character to the prohibited character list.

e.g.

If the old PCL was He\., and you managed to write a program that doesn't use any of these characters, you may add a new character to this list. For example  (whitespace). The new PCL will be He \. (notice that the whitespace character is added).

### Posting Snippet:

#[Language Name], N bytes

[code]

(explaination etc.)

New PCL: [list + new char]


In the beginning, the PCL is empty. The last person who managed to create a program without a new program made in 2 days, wins!

I'm not really sure if it is flawed or not. If you have any suggestions or comments, feel free to post them below in the comment section :)

• Already exists. – Arcturus Nov 22 '15 at 23:38

# What day of the week is Christmas?

Christmas is coming quickly, which leads to the question, what day of the week is Christmas this year? But what day of the week is Christmas for any year? Write a program that can do this. This is code golf, so the shortest code wins!

However, there is a major twist. No builtin functions to do this task is allowed!

Bonuses:

1. If the program can handle B.C. years as negative numbers, then -25%
2. If the program prints "The first Christmas!" for an input of -4 (4 B.C. is assumed to be when Jesus Christ was born), then -30 bytes
3. If, for some reason, you really like builtins, +90%! So try NOT to use it!
• The bonus for printing extra should be steeper, or no esolangs are going to go for it. – Addison Crump Nov 29 '15 at 1:45
• @VoteToClose so more like 25% as well? – TanMath Nov 29 '15 at 1:48
• No - I'd go static. Plus, this is really close to being a dupe... – Addison Crump Nov 29 '15 at 1:51
• Near dupe of codegolf.stackexchange.com/questions/1003/… – Calvin's Hobbies Nov 29 '15 at 1:52
• It's unspecified what format we should output in or what calendar we should use, and whether -4 should mean 4 BC or 5 BC. – lirtosiast Nov 30 '15 at 5:57
• @ThomasKwa it should be obvious from the sentence that 4 B.C. is -4. Use the Gregorian calendar, output can be in MMDDYY – TanMath Nov 30 '15 at 6:09
• How is MMDDYY a day of the week? – lirtosiast Nov 30 '15 at 16:32
• @ThomasKwa sorry, it was pretty late when I wrote that so I mistakenly wrote MMDDYY. Just printing the day of the week is fine i.e. print "Sunday", "Monday", "Tuesday", etc. – TanMath Nov 30 '15 at 19:57

# Golf A Wiki

## The Challenge

Golf a wiki. A wiki, for the purposes of this contest, is defined as a website with:

• Content editable by all
• Easy CamelCase (defined as a word with two capitals) linking
• Different pages or articles that are the targets of the links

Your wiki can be a self-contained HTML file (e.g. TiddlyWiki), or a cgi-bin script (e.g. SigWik).

## Scoring

Your score is the size of your program in bytes, divided by the number of extra features implemented plus one.

The possible extra features are:

• Page history
• Syntax for "nowiki", that is, something like <\noscript> in HTML that makes the text inside it not be wiki syntax.
• A page list
• A find page facility
• Security levels (requires usernames and passwords, or possibly IPs?)
• Delete pages
• Change page titles
• Redirects
• Random page
• Non-HTML formatting that is not just links [Should I remove this? I doubt it will be done.]

Lowest score wins, as this is code golf.

# DISCLAIMER

ANSWERS WILL PROBABLY CONTAIN MAJOR SECURITY FLAWS. ONLY USE ON PRIVATE PORTS, UNLESS YOU WANT YOUR COMPUTER AND VERY POSSIBLY YOUR WHOLE NETWORK TO GET DESTROYED (FIGURATIVELY). [Is this too forceful?]

• I would vote to close this as too broad. Among the problems I see: 1. The two given examples don't seem to be the same thing as each other 2. The complete lack of constraints mean that I could just automatically make every word a link. (This could be fixed by specifying one link syntax: for golfing I quite like the UseModWiki use of CamelCase for links). 3. I think I can get the "text formatting" feature for free by not escaping HTML characters. 4. Needs a big warning "Answers will likely contain major security flaws and should not be used on ports which are publicly visible" – Peter Taylor Dec 30 '15 at 10:49
• Ok, thanks, I'll edit when I have time today. – Hipe99 Dec 30 '15 at 21:27

## Progress 100%

I am building a download manager and I need to show a progress of all my files been downloaded.

For that I created an event mechanism that reports on the progress of each individual file. It sends me the information on how many bytes B have been downloaded of file T total.

Please help me show the average progress of all the files.

## Input

Integer C between 1 to 100, followed by new line, followed by C progresses separated by new line. Each progress is constructed of two numbers with the maximum size of 64 bits: B T, separated by space.

Input options

The input is a String available from the following options

• file
• stdin
• method parameter

## Output

Floating number between 0 to 1, the average of all the progresses. It must be displayed to 11 decimal places, floored.

## Criterial

Shortest code wins

## Example

Input file:

3
5 10
1024 1024
20 100


Output

0.56666666666


Explanation

((5/10) + (1024/1024) + (20/100)) / 3 = 17/30


## Example2

Input file:

1
2 10


Output

0.2


## Example3

2
Long.MAX_VALUE Long.MAX_VALUE
5 10


Explanation In this example Long.MAX_VALUE represent the maximum 64 bit value, so if you use 64 bit value for storing the sum of the averages it will not work in this case.

Output

0.66666666666

• 1. It's not clear from your specification how the result should be computed. The "total progress" implies to me that I should figure out how many bytes have been downloaded of the total, i.e. sum(B)/sum(T). However, your first example suggests, that we should actually compute the arithmetic mean/average of the individual progresses. If so, please state this clearly. 2. By requiring 11 digits of accuracy, you require 64-bit floats (double precision), because 32-bit floats only have 7.something decimal digits. Is this intentional? (seeing your input is only 32 bits) – Martin Ender Apr 1 '15 at 20:39
• @MartinBüttner how about now? I do want the high precision – Ilya Gazman Apr 1 '15 at 21:24
• My first point still stands. It's not clear from the specification how the result should be computed. – Martin Ender Apr 1 '15 at 21:27
• @MartinBüttner I expect you to process all the progresses and find the average one, not sure how to say it right. – Ilya Gazman Apr 1 '15 at 21:28
• Just like that, but as far as I can see your challenge currently doesn't mention "average" or "arithmetic mean" anywhere. – Martin Ender Apr 1 '15 at 21:32
• @MartinBüttner Anything else? – Ilya Gazman Apr 1 '15 at 21:40
• Why did you remove it again? And what's the purpose of the hint? – Martin Ender Apr 1 '15 at 21:43
• @MartinBüttner sorry had 2 windows opened. The hint helps you to understand that you cannot store the sum of all the progresses in 64 bit value. – Ilya Gazman Apr 1 '15 at 21:45
• What does "up to 11 digits of accuracy mean"? That I can supply only 3 digits, but I may not supply 12? And what counts as a "digit of accuracy", anyway: are you talking decimal places or significant figures? And if significant figures, what is the correct output if the average progress is exactly 0? – Peter Taylor Apr 1 '15 at 22:37
• @PeterTaylor I want an 11 digits after the dot of accuracy in the output. So 3/10 will produce 0.33333333333 and 0/10 will produce 0. Maybe you can suggest a better way of writing it down. – Ilya Gazman Apr 1 '15 at 22:40
• I've edited in some changes. I would suggest also deleting the hint and replacing it with a test case. It would also be good to describe a test case (it will probably be too long to post) which demonstrates that it's not sufficient to use IEEE754 double-precision. – Peter Taylor Apr 2 '15 at 7:35
• @PeterTaylor is it ready now? – Ilya Gazman Apr 2 '15 at 14:09
• It would also be good to describe a test case (it will probably be too long to post) which demonstrates that it's not sufficient to use IEEE754 double-precision. – Peter Taylor Apr 2 '15 at 19:28
• @PeterTaylor I don't understand what you are saying, can you please explain it a little bit more – Ilya Gazman Apr 2 '15 at 20:15
• Since you're requiring programs to support averaging 2^31 numbers and you want output to a precision of about 35 bits, a naïve solution with 64-bit floating point will be incorrect, but that might not be obvious to everyone who would attempt an answer. – Peter Taylor Apr 2 '15 at 20:23

Write a polyglot (a program that works on several languages) that produces the // this is a comment output.

## Example (JS + Plain PHP + Plain HTML) (74 / 3 = 24.66 points)

// this is a comment<?php ob_start();?><!--
alert("// this is a comment");


## Another Example (CoffeeScript + CJam + brainfuck) ()

e###-[----->+<]>----..+[--->++<]>.---[->++++<]>.------------.+.++++++++++.+[---->+<]>+++.-[--->++<]>-.++++++++++.+[---->+<]>+++.[->+++<]>+.-[->+++ <]>.+[->+++<]>.++++++++++++.--..--------.+++++++++.++++++.
"// this is a comment"
e### alert "// this is a comment"


## Scoring

Your score will be code byte length / num langs

The smallest score wins!

• Is there anything that makes this significantly different than polyglot Hello World? – Geobits Feb 1 '16 at 14:03
• @Geobits this is more easy, really – username.ak Feb 1 '16 at 14:37

# Linear Time Sorting

It was another slow day at Initech Inc. when a feature request came in:

New Feature: Ability to sort by cash value in the transaction form. But make it a fast one!


Well it looks simple.. but what do the requester mean by fast one? Let's call Jim, from sales he probably knows what's going on.

Jim: Well you know , our Business Inc. contact is very passionate about

programming and computer science! In fact he had this idea that we should

do sorting in how that was called.. linear time?

You: Well you know that's impossible?

Jim: But it was already approved by their cto and all! You need to do something


You and Jim came up with a plan.. nobody will notice if that big of a list isn't sorted enough, right?

Your task is to write a linear time sorting program. It will be scored on accuracy of the sort as compared to list sorted by regular sorting algorithm but it must work on O(N) time in the worst case, where N is length of the input.

Input will be in the form of list of string-double tuples, e.g:

[("aaaa",2.0) , ("aaba",1.0)]


The program should sort on the number value of the tuple, i.e. in the above case the order should be reversed. There may be multiple inputs with the same double values, but no string value is repeated. In the event that two inputs have the same integer value the perfect solution is to keep the order as it is. The double value may be any floating-point value that fits in 8 byte double precision variable. NaNs should be placed at the end of the list.

The score is calculated as number of "bubble sort operations" (switch an element with the next/previous element) needed to achieve perfect output from the output of your algorithm.

# Sandbox Worries

Well I don't know how clear my explanation of challenge was and if it is interesting to the PPCG crowd.

Obviously there is a need for testing program and test cases.

• How big will the test cases be? If you pick a fixed size, the response will be "n passes of bubble sort where n is the size of the largest test". Bam, linear with perfect score. – John Dvorak Apr 11 '16 at 10:12
• @JanDvorak I rephrased the scoring sentence to more reflect what I meant. In that case the score wouldn't be perfect as after just n switches the list wouldn't be the most ordered. EDIT: I think I understood it now. Well I think you can somehow exclude answers like that with some caveats in the rules, like "Your algorithm cannot make any assumtions about length of the input" – Lause Apr 11 '16 at 10:17
• I don't make any assumptions. It sorts every array up until the largest test case correctly and all other arrays partially. – John Dvorak Apr 11 '16 at 10:28
• An algorithm that fares better than n-pass bubble sort is to do a level-n mergesort. If the length exceeds 2^n, sort each [k::len/2^n] subarray separately. – John Dvorak Apr 11 '16 at 10:32
• But then you're making assumptions based on the size of the test cases - if somehow the test cases were changed (but still fitting the rules) to test cases which are much longer (for example you prepared for max 10 element list and you get 100000 element list) your program isn't linear. – Lause Apr 11 '16 at 10:41
• The problem with a spec is that it cannot change once you've posted the challenge, and you can't define "making assumptions based on the size of the test cases". You can't even ban all magic numbers - I can simply use functions merge1 .. merge20 – John Dvorak Apr 11 '16 at 10:47
• It isn't the spec - the way the test cases used to grade the result are constructed is described but do I have to post the test cases (but those used to score) themselves? – Lause Apr 11 '16 at 10:50
• You need to define the test cases, and you can't change them based on the answers (if only because updating the score of every answer would be a nuisance). Maybe you could ask for asymptotic behavior, but that can be surprisingly hard to measure. – John Dvorak Apr 11 '16 at 10:53
• Hidden test cases are a problem as well, because then we can't test the submissions after you're gone. – John Dvorak Apr 11 '16 at 10:55
• The idea was to pregenerate some test cases (undisclosed) and some test cases that are disclosed (for testing purposes during the coding) and then do a cutoff time for the challenge where all the solutions are tested against the undisclosed challenges. Also obviously after the cutoff time the test cases would be disclosed. – Lause Apr 11 '16 at 10:56
• 1. Most real-life data types can be sorted in linear time, so the premise of the question seems badly flawed. 2. "Input will be in the form of list of string-double tuples ... There may be multiple inputs with the same integer values" Huh? Where do the integer values come from? 3. "The double value may be any floating-point value" Where do NaNs sort? – Peter Taylor Apr 11 '16 at 16:00
• 1. The idea is that the data may be the worst case for any algorithm that can achieve linear sorting time 2. It was a typo 3. At the end - I will put it into the question – Lause Apr 11 '16 at 18:36
• Why does the input being worst case make any difference? The solution will still be perfect, so you'll need a tie-breaker to separate every single answer. – Peter Taylor Apr 11 '16 at 21:27

# Make a quine without using string literals popularity-contest

A quine is a computer program that prints out it's own source code to stdout. Your task is to make one that doesn't use string literals.

You cannot:

• Have any empty program
• Read your source code directly or indirectly (i.e. form a file)
• Use error messages to print out the source code
• Rely on language features to print out the source
• Relying on a REPL environment

A string literal is a:

• String type (obvious)
• Number used to store the character (sorry BF!)
• Other predefined constant

You are encouraged to compute your own source code.

• This hits two of the "things to avoid when writing challenges": do X without Y and popcons. (I assume it's an attempt to finesse a third: generalised quines). It also has some fairly bad phrasing: what language can print anything without using "language features"? In what way does BF use literals? How many languages can compute anything without using at least one constant? – Peter Taylor Apr 12 '16 at 7:27

## Cops and robbers : Programmers/Hackers

• This challenge is quite different from my previous challenges. This challenge is an endless competition between robbers and cops, which are respectively hackers and programmers. One of them will ever win!!!

• This will evolve to code de/obfuscating when it gets to the higher stages: a skillful programmer who is struggling to save his program from a sourcecode-mangling attempted by a cunning "robber" who tries to impose his existence by patching his name instead of the name of the "programmer" in the output console without changing anything else in the code. The story begins this way:

• Programmer is at the point of executing his recently made C code, so he included this trivial line to show off:

C (1)

    printf("[Programmer's username]")


After executing this program programmer saw this on the screen:

[Robber's username]


which indicates the presence of some evil code at the compiler level that compromises his code, which follows:

Matlab (2)/parser

      a=findstr(code,'printf(''[Programmer's username]'')'); if a code(a:20)='printf(''[Robber's username]'')';end


The programmer cannot modify the counter-program in the compiler, so he must rather change the program content to escape the twiddling:

PHP (3)

      $a='[programmer's username]';echo$a;


The score is now 3, which is the number of steps from the beginning. The current user would win only if the hacker did not figure out something like:

PHP/Regex(pcre flavor) (4)

      $code=ereg_replace("(\$\w)\='programmer';(.*?);echo\s\1","\1\='robber';\2;echo\s\1",$code)  Since the solution above does not satisfy the rules (see the bottom of this question), the score stays unchanged, and the programmer can make a counter example, and take out the score from last submitter with a penalty on his score equivalent of how much he earned in the earlier level, where the counter example can be something as: PHP (4) $a='programmer';$b=$a;$a='unrelated';echo$a;


Or he can adjust his program in higher scale to escape all the regex-trapping in a superior range, So the cycle goes on until no post can be added and the last submitter before the end of June is declared a potential winner meanwhile.

The hacker can also fix his regex and regain his score, so the recent scoring will be abrogated from programmer.

Perl/dynamic-regex (4)

local @a=('');

sub check{
if (grep {$_ eq @_[1]} @a) {push @a,@_[0]; } elsif (grep {$_ eq @_[0]} @a)   {
my @del_indexes = grep { @a[$_] eq @_[0] } 0..$#a;
foreach $item (@del_indexes) { splice (@a,$item,1);
}
}
return 1;
}

sub actor{
if (grep {$_ eq @_[0]} @a) {return "print robber";} else {return "print ".@_[0];} } sub initiate{ push(@a,@_[0]); return 1; }$code =~ s/(((\w+)\="programmer"(??{initiate($3);}))|(print\s(\w+))|((\w+)\=(\w+)(?{check(($7),($8));})(?1)))/print($2);actor(\$5)/pegmx;


As you can see this Perl program prints b in the first case because the variable b is compromised after the first assignment, but in the second case the regex modifies the output because d receives the target-string transitively. Let's just stop here and not mess the fun (of course, if there will be some).

## Scoring and rules

How is the score counted ?

• Any hacker/programmer is scored for his code as the actual level L the game is on.
• A partial dynamic regex within the core of the program is scored L + (2^L)/log(length of program + length of characters which do not belong to the regex)), where the log is base 2. For the second example of level (4) the length of the compacted program is 480, and the length of regex is 136, so the score is 4+2^4/log2(480+480-136) ~= 4+16/9.6
• A fully functional regex as in the first example level (4) is scored L + (2^L)/log(length of regex), where the log is base 2, in that case S = 4 + 2^4 / log(91) ~= 4+16/6.5
• Scores are added progressively to submitters, and when a level is surpassed with no regex, it is still open for scores, while the actual winner remains unchanged.
• A penalty on a certain-leveled score when the regex/parser is revealed out of rules and the game is regressed to this stage until the issue is fixed, rules are cited below:

Rules:

• The main rule: the hacker-program must compromise an output to the console, which is the username of the programmer. Any other behavior is unaccepted simply because a string variable of [programmer's username] can be used in other order rather than printing, a counter-example is easy, converting the string to integer then use it for arithmetic calculations that harms the main program once intentionally modified.
• Also one of the following factors declared by any counter-example bans the targeted flawed regex/parser as non rule-complying:
• The regex/parser prints anything other than a chosen string preferably set as the username of the robber.
• The regex/parser generates a program which does not compile.
• The regex/parser does not print anything, or compromises a segment of code that is needed for tasks other than printing .
• The variable which stores the program is named code by default, also you may assume that is one-liner, and any non-significant spaces are omitted, and that it is fully working by default.
• The regex/parser deals with one variant of one code proportion in a comprehensive way, i.e. if a print function is used, that encompasses all printing functions in all languages puts,disp,..etc. Also, code separators can be unified to one characterL either , or ; or a significant space needlessly of enumerating all keywords/syntaxes, this is not a contest about a working code in a specific programming language.
• To prevent endless program/regex loops let's just not making a jokey sequence as a='programmer';print a / /(\w)\='programmer';print\s\1/ / a='programmer';b=a;print b / /(\w)\='programmer';(\w)\=\1;print\s\2/ because the first person who makes a regex/parser which palliates to a same replicated idea will take out all attributed scores to this idea from their owners, so any anaphoric sequences like this in addition that they are set to same level, they are unneeded.
• Any language that uses pointers/addresses/classes like C++ are welcome, as long as they help to evade the hacker.
• Please, for the love of god, spell things correctly. In the first bit alone I spotted a ton of spelling mistakes without even looking for them. Also, that whole first list is... basically impossible to understand, at least for me. Maybe use full sentences? – Fund Monica's Lawsuit May 10 '16 at 21:29
• Have you seen our cops-and-robbers challenges? It sounds like that is what you are trying to do here. That said, there are a couple of problems with the spec: Defining what parts of the language counts as a "partial regex" or "full regex" is really tough, especially when we get into esoteric languages. – Nathan Merrill May 10 '16 at 21:36
• Could you add a short summary to the post? I don't understand what the actual task here is. Is this a cops-and-robbers or answer-chaining challenge, or something entirely different? – Zgarb May 10 '16 at 21:36
• i will see what cops and robbers is – Abr001am May 10 '16 at 21:39
• @NathanMerrill this is not a code golf so i dont see the point of introducing esolangs here – Abr001am May 10 '16 at 22:28
• @Agawa001 Esoteric languages are still useful outside of golfing. You can use them to make it tough for regexes to match. – Nathan Merrill May 10 '16 at 23:06
• The introduction is very long and after reading it I have no idea what the task is. I would have to vote to close this as "Unclear what you're asking" in its current state. – Peter Taylor May 11 '16 at 7:45
• So what's the core mechanic? Is this an answer-chaining question where answers must alternate programmer and hacker? But if the programmer can change language at will, how can the hacker hope to win? – Peter Taylor May 12 '16 at 12:06
• @PeterTaylor yes it is answer chaining but the last submitter can post two consecutive answers and be the robber and cop themselves, the programmer change his code, hacker changes his regex taken consideration of all last regex/parsers. – Abr001am May 12 '16 at 16:13
• I have no idea what this challenge is supposed to be. The very little explanation of the concept is muddled by spelling and grammar issues. Please, learn English spelling and grammar before trying to write a challenge. – user45941 May 13 '16 at 5:18
• @PeterTaylor refer at the 4th rule, procedures which accomplishes a specific task in different languages are dealt as one thing, this is not a challenge about checking language-syntaxes, when a programmer changes language, consider all previous regex/parsers changed to trap same functionnalities of previous code on the new language. – Abr001am May 28 '16 at 11:37

## Challenge

Write a program that takes an numerical input n and outputs the nth number that is not a perfect square.

## Rules

This is , so least bytes wins.

• What's the maximum expected input? Does it expect 0? How do we handle 0? Is there a requirement on the efficiency for large inputs? Also give some example inputs and outputs. – Patrick Roberts Jun 17 '16 at 20:19
• Here's some test cases I just generated: 1->2,2->3,3->5,4->6,5->7,6->8,7->10,8->11,9->12,10->13,11->14,12->15,13->17,14->18,15->19,16->20,17->21,18->22,19->23,20->24,21->26,22->27,23->28,24->29,25->30,26->31,27->32,28->33,29->34,30->35,31->37,32->38,33->39,34->40,35->41,36->42,37->43,38->44,39->45,40->46,41->47,42->48,43->50,44->51,45->52,46->53,47->54,48->55,49->56,50->57,51->58,52->59,53->60,54->61,55->62,56->63,57->65,58->66,59->67,60->68,61->69,62->70,63->71,64->72,65->73,66->74,67->75,68->76,69->77,70->78,71->79,72->80 Is this the function you expect? – Patrick Roberts Jun 17 '16 at 20:41
• Yes, yes it is. – weatherman115 Jun 17 '16 at 20:42
• Can you address my other questions please? Namely, the largest expected input and how to handle input of 0. – Patrick Roberts Jun 17 '16 at 20:43

# Generate all variations of a string with every combination of upper and lower case for each vowel but leaving consonants and order of letters unchanged.

This is a simplified analog of a problem I've thought about a few times over the years based around variant spellings in different spoken languages.

Input is a text string. Output is an array of all variations of the text string.

A "variation" means the same letters in the same order but for each vowel letter in the string we generate a version of that string with the vowel in uppercase and the vowel in lowercase.

No variation should be included more than once. No legal variation may be omitted.

# Example

## Input

codegolf

## Output

• codegolf
• codegOlf
• codEgolf
• codEgOlf
• cOdegolf
• cOdegOlf
• cOdEgolf
• cOdEgOlf

The winner shall be the most elegant as voted by the community.

"Elegant" includes that the algorithm should be optimal in terms of Big O notation, should be concise, should be idiomatic making good use of available features of the implementation language.

Length of code characters or bytes is not relevant.

Programming language is open.

• "most elegant as voted by the community." I doubt many answers to such a challenge will be deemed elegant. – Fatalize Jun 23 '16 at 13:01
• Really? Anything to suggest instead? Just "best" is usually no good for Stack Exchange... – hippietrail Jun 23 '16 at 13:22
• Code golf version of this challenge: codegolf.stackexchange.com/q/80995/8478. That said, I don't think "most elegant" makes a good popularity contest and is very likely to be downvoted and closed almost instantly. If you're looking for elegant solutions, this might not be the right community in the first place though. You could write your own solution and post it on Code Revew to ask for improvements. We generally require objective winning criteria for our challenges, and popularity contests are in a weird place where you need to come up with something really good for it to be accepted. – Martin Ender Jun 23 '16 at 13:30
• Hmm well OK whatever. – hippietrail Jun 24 '16 at 11:55

# Oh noes! A site redesign is eating my privileges!

PPCG is graduating and will soon receive a new design. Unfortunately for everbody except some people, the new design will also mean losing privileges due to higher reputation requirements.

Now, losing some privileges is a small sacrifice for the Magnificent Glorious Site Redesign®©™, but… How much do we stand do lose?

## The challenge

Your program / function receives a reputation level (e.g. 535). Output the privileges that are currently available to it, but will not be available after the redesign.

### Output

Output can be either an array or a string that's separated by a delimiter. The delimiter may not be any of A-Za-z<space>. Multi-character delimiters may end in a space, though.

If there are no matches, your program should output either an empty array or a falsy value.

### Examples

Input
25000

Output
[]

Input
24999

Output
["access to site analytics"]

Input
2000

Output
["access to moderator tools","approve tag wiki edits","cast close and reopen votes","create tag synonyms"]

Input
535

Output
["cast close and reopen votes"]

Input
350

Output
["access review queues"]

Input
5

Output
[]

Input
4

Output
["participate in meta"]


Deliberately ignoring the facts in the last example.

### Available privileges

For convenience, here is a JSON array with available privileges and the required reputation before / after:

[[5000,25000,"access to site analytics"],[4000,20000,"trusted user"],[3500,15000,"protect questions"],[2000,10000,"access to moderator tools"],[1500,5000,"approve tag wiki edits"],[500,3000,"cast close and reopen votes"],[1250,2500,"create tag synonyms"],[1000,2000,"edit questions and answers"],[750,1000,"established user"],[1000,1000,"create gallery chat rooms"],[350,500,"access review queues"],[150,300,"create tags"],[250,250,"view close votes"],[125,125,"vote down"],[100,100,"edit community wiki"],[100,100,"create chat rooms"],[75,75,"set bounties"],[50,50,"comment everywhere"],[20,20,"talk in chat"],[15,15,"flag posts"],[15,15,"vote up"],[10,10,"remove new user restrictions"],[10,10,"create wiki posts"],[1,5,"participate in meta"],[1,1,"create posts"]]


At index 0 is the reputation before, at index 1 is the reputation after. (The privilege reduce ads (200 reputation) is not available to beta sites and therefore not included in this list.)

Standard I/O and loophole rules apply.

• Related. It's borderline whether this adds enough to not count as a duplicate: I would vote that it does, but I wouldn't cast my supervote. – Peter Taylor Jul 12 '16 at 16:21
• @PeterTaylor I'm thinking of changing the challenge to allow submissions to download the privilege page. I guess that would make it distinct enough. – user2428118 Jul 13 '16 at 10:53
• Turns it into a hybrid parse-HTML and merge data sources question. Yes, I think that's novel. You should make it very clear that the answers should keep working after the contents of the privilege page are updated to show the new rep levels; and possibly you should take a backup copy of the page in case of future addition of new privileges. – Peter Taylor Jul 13 '16 at 11:01