The Nineteenth Byte

Alex A.

00:03

I have a feeling it won't happen, unfortunately.

Alex A.

00:42

You know, @Dennis, you could post a Chef answer. ;)

Nathan Merrill

01:25

hey, I'm looking for API advice for this challenge:

2

A: Sandbox for Proposed Challenges

Ironclad Tactics KoTH This KoTH is inspired by the Ironclad Tactics paper version from Zachtronics. The game is played on a 9x4 grid split into three areas: the North, the South, and No-Man's-Land (the center). To make things easier for you, it will always appear that you are the North (the le...

how would you prefer the tank be organized?

3 different types, and a list of Attacking square offsets?

New Main Posts

02:36

0

Q: Pow of natural numbers

The challenge Implement the C equivalent of the pow() function (exponentiation) for natural numbers, in a language of your choosing, without using any library functions or operators for exponentiation, multiplication, or division. You may use addition, subtraction, bit-shifting, and any boolean ...

0

Q: Yarr! A map to the hidden treasure!

Introduction "Yarr!! We had a laddie who called himself a "programmer" make a map t' our hidden treasure! But 'tis written wit' weird numbers 'n letters! "E5, N2, E3"... what does it even mean? Madness! Can't even scribe a proper treasure map, t' useless cretin. Fix it fer us! We'll gift ye a sh...

code-golf

Alex A.

02:50

@Pyrrha Yarr!

Sp3000

@NewMainPosts It's a do basic X without obvious Y :(

Alex A.

^

Geobits

I did it in Java, not BASIC. Is that ok?

Alex A.

Nope

Geobits

Well damn.

Reto Koradi

02:57

I still can't believe that people used languages other than Python to solve the "kissing snakes" challenge recently

Alex A.

Other languages can kiss snakes too, you know.

Who are we to deny them their snake love?

Reto Koradi

@Sp3000 I was hoping to find one of the CJam gurus. I guess it's you. :) Do you know a good way to strip leading spaces off a string? So far the best I found is 9 bytes, which seems awful

Alex A.

I tried to be smart but it didn't work

Sp3000

My first idea would be something like {S=!}#> assuming there is a nonspace char

(can't test atm)

Basset Hound

What's the ! do in that case?

Alex A.

03:09

It yells

Basset Hound

Seems legit

Alex A.

Trust me, I "know" CJam.

Sp3000

It's Boolean NOT

New Sandboxed Posts

0

A: Sandbox for Proposed Challenges

Question about generating pseudo Lisp code (title tbd) Synopsis: Given a list in the Lisp style and a letter in that list, return the appropriate car and cdr statements to return that letter, given that the list is stored in a variable l. In Lisp style languages, a list looks something like...

Alex A.

(for some loose interpretation of the word "know")

Reto Koradi

03:10

@Sp3000 Let me try. I don't think I had ever noticed that you can use a block with #.

Basset Hound

Boolean not?

Sp3000

Try checking the remove leading spaces question

Alex A.

@BassetHound Not True == False.

Basset Hound

Oh.

Alex A.

Negation

In logic, negation, also called logical complement, is an operation that takes a proposition p to another proposition "not p", written ¬p, which is interpreted intuitively as being true when p is false and false when p is true. Negation is thus a unary (single-argument) logical connective. It may be applied as an operation on propositions, truth values, or semantic values more generally. In classical logic, negation is normally identified with the truth function that takes truth to falsity and vice versa. In intuitionistic logic, according to the Brouwer–Heyting–Kolmogorov interpretation, t...

Reto Koradi

03:15

@Sp3000 {S=!}# gives an error. I tried {S-!}#, which does not give an error, but does not give the desired result. I'll play with it some more

Dennis

@Sp3000 S is a string, not a character, so = will raise an error. _{S^}#> will work though.

@RetoKoradi It should be {S-}#, without the negation.

Alex A.

@BassetHound What's your background with programming like?

Programming and/or computer science

Reto Koradi

@Dennis Right. I was playing with loops to try and solve it so long that I got used to negating it.

Sp3000

If everything else is separated by 1 space then you can use S%S*

(Not sure what question this is for)

Alex A.

(Could be for general furthering of knowledge)

Reto Koradi

03:18

@Sp3000 There can be sequences of multiple spaces in the rest of the string. I was thinking of splitting at spaces, but that's where it broke down.

@Dennis Is _{S-}#> the shortest you can think of for stripping leading spaces? It's 2 bytes less than the 9 byte solution I had, so that's progress.

Well, I think I hadn't counted the _, so it's 3 bytes less.

Dennis

@RetoKoradi There's also __S-c#>, but it's just as long. CJam needs a trim operator...

Basset Hound

Is there a way to get the first two characters of a string in Python?

@AlexA. Not all great.

Doorknob

@BassetHound s[:2]

Basset Hound

03:33

Alright, cool

Alex A.

@Pyrrha Could you use integers?

So rather than a b c you'd use 1 2 3?

Pyrrha

integers could work

Alex A.

It'd make output testable

Pyrrha

although you'd still need the (list 1 2 3...) construction

Alex A.

No, you can use a leading apostrophe

(car '(1 2 3))

Pyrrha

03:35

Hmm okay

Alex A.

repl.it supports Scheme, which supports the same car and cdr syntax as regular Lisp.

So that'd be a way to test submissions.

Basset Hound

So it converts to a string, then what? @Doorknob Getting an error

Alex A.

@BassetHound s has to be a string

Basset Hound

Yes, it is

Doorknob

What error?

Alex A.

03:37

@BassetHound Then what's converting?

Doorknob

llama@llama:~$ python -c 'print "foo bar baz"[:2]'
fo

Alex A.

@Pyrrha Are you going to come play Minecraft again sometime?

Basset Hound

Oh, I see the problem

I'm an idiot. I meant CJam xD

Pyrrha

@AlexA. Yes. Don't know when though.

Alex A.

@Pyrrha Fair enough. Haven't seen you around in a while. Hope things are going well.

@BassetHound You're not an idiot. But getting the language right does come in handy. ;)

@Doorknob llama@llama -- Is Optimizer in your computer?

Basset Hound

03:41

Yes, that is truth.

Alex A.

:)

Reto Koradi

@BassetHound In CJam, 2< gives the first two characters of a string. While the documentation is kind of... concise, there is a list of operators here: sourceforge.net/p/cjam/wiki/Operators

< is the "slice left" operator for arrays/strings (strings are just arrays of characters)

Alex A.

@PhiNotPi I can't not read your starred post as saying "when the starboard is filled with feces." :(

Reto Koradi

@Dennis The OP on the "power" question posted clarification. And yes, a trim operator would be handy. A "find not" would also have helped somewhat in this case. Which starts going in the direction of regular expressions.

Alex A.

@RetoKoradi Regular expressions for exponentiation?

Basset Hound

03:53

@RetoKoradi Alright, thanks. Most of the explanations there aren't enough for me.

Alex A.

I'm bored and don't want to do the things I should be doing. :|

Reto Koradi

@BassetHound I started writing my own notes when learning CJam. I just tried each operator with various kinds of arguments, and tried to make sense of the result. For most of them it was fairly straightforward. There are a couple that I initially had trouble understanding, like the various uses of : and f. Looking at solutions from some of the regular posters, with their explanations, is also highly instructive.

@AlexA. Nah, completely unrelated. I was just mixing two topics in one message. It's called efficiency. :)

Alex A.

Efficiency? I'm not familiar with this concept. :P

Reto Koradi

@BassetHound BTW, if you haven't seen it, the ed operator is highly useful during learning and debugging. It shows the current content of the stack.

Basset Hound

04:12

Thanks for the help @RetoKoradi ^.^

Sp3000

I'll try and get the part 2 (arrays) of the tutorial done tonight - just took it back down to add Dennis' suggestions

@AlexA. Close enough? (input a^b as an a*b grid)

Alex A.

@Sp3000 ಠ_ಠ

Surely this is a sign of the end times.

(And by that I of course mean awesome, nice work :D)

Sp3000

Retina could probably do it in a more legit way :P

Alex A.

Still great.

Dennis

@RetoKoradi Fixed.

Reto Koradi

04:31

@Dennis Looks good. I was almost tempted to try a nested loop of additions, but then I decided to try another challenge.

Dennis

Yarr?

Alex A.

Dosas, perhaps?

Reto Koradi

No, not one of the most recent. @AlexA. Not that one either. I tried to read it, but it confused the hell out of me.

Alex A.

@RetoKoradi Oh no! Is there anything I can do to make it clearer?

Reto Koradi

@AlexA. It's probably clear if somebody really wants to get into it. It started going beyond my attention span once it began talking about waiters carrying around different sizes. I'm sure it's a fine challenge, just not my cup of tea... or rice...

Alex A.

04:39

Fair enough. :)

Reto Koradi

Sometimes first impressions can be wrong. Dennis almost lost me the first time I read that bijective bases thing. It first looked like a challenge for mathematicians. But it wasn't nearly as complicated as it looked, and really fun.

Alex A.

Oh hey, to my surprise, somebody upvoted pow().

Sp3000

There's bound to be

Dennis

04:57

I finally figured out why some CJam permalinks don't work in Firefox while others do.

Alex A.

Why?

Dennis

Firefox requires escaping a % as %2525, which gets replaced by %25, then %.

That ought to be a bug somewhere.

Sp3000

!?

Alex A.

That's... huh.

Dennis

Yup, that's it.

As far as I can tell, the hash of the URL is automatically decoded in Firefox.

But the CJam interpreter attempts to decode it a second time, which results in an error.

Just visit google.com/#%25 in both browsers and execute window.location.hash in the console.

Sp3000

05:15

@Optimizer ／人 ◕‿‿◕ 人＼ Make a contract with me and become a w magical girl!

Alex A.

@Sp3000 Uh what

Sp3000

Alex A.

...

Alex A.

05:28

(ºnº)

Sp3000

ξ(✿ ＞◡❛)ξ▄︻▇▇〓〓

Alex A.

∂.∂

PhiNotPi

05:54

@Sp3000 ξ(✿ ❛◡❛)ξ▄︻▇▇〓〓 aim with both eyes open, it's twice as accurate

Optimizer

06:13

@Sp3000 soo mesmerizing and enchanting.. Digimon ? or what..?

@PhiNotPi no its not. You should see professional shooters shoot

Sp3000

Puella Magi Madoka Magica, which should be where that emote's from :)

Reto Koradi

@Sp3000 Here is where I needed the string trimming: codegolf.stackexchange.com/a/54307/32852. It turned out to be a slightly more complicated case, because I needed to trim 2 characters. Ended up with a nested #, which is kind of cool. I'm fairly happy with that part. Putting the whole thing back together was slightly more painful, I should take another look at that later. I did use Martin's string combination trick with .e<

Sp3000

It's a lot easier for that question because you can do '_#>

Reto Koradi

For the sorting, I need to trim leading spaces, the _, and then more leading spaces to get to the text.

Sp3000

Oh right, the sorting

Reto Koradi

06:24

{" _"#W=}#> seems quite reasonable for that.

To pack two strings into an array, there's no way around applying an a to both of them first, and then concatenate, right? Otherwise it adds the string to the array character by character. Which is logical, since the string is an array.

Sp3000

Yeah

[\] is shorter depending on what order you need them

Dennis

@RetoKoradi {_{" _"#W=}#>}$ should work.

Reto Koradi

@Sp3000 oh, right, I keep forgetting that I can put the [ and ] anywhere in the code. Even though I've used it before.

@Dennis Wow. I think it does. What exactly is it? Can $ take a block as an argument?

Sp3000

06:41

$ takes a block as well, yeah

Reto Koradi

Cool, I guess I learned something new today. I had never seen that. So this means that it applies the block to each array element, and then sorts based on the result of evaluating the block for each element?

Sp3000

Yep, and should probably mention that order is preserved on ties

(I think?)

Reto Koradi

Seems likely that it uses a stable sort algorithm.

Sp3000

I checked the docs yesterday and Java uses stable sort, so I'd assume so

btw same number of bytes, but 1> is a bit nicer than (;.

New Main Posts

0

Q: checking for palindrome

Write a Program to take and INPUT STRING and identify whether it is a PALINDROME or NOT. The output should be generated as 'Y' or 'N'. The program should take input both from command line as well as console(STDIN)

palindrome

Optimizer

06:56

^ possibly dupe if code-golf, otherwise off-topic for having no criteria

Sp3000

Pow is up to -1

Optimizer

Pow Pow

Pow Pow Pow

Reto Koradi

07:08

@vihan I think I saw you check in just a little earlier. Just wanted to say that the textbook challenge was great, IMHO. Definitely one of my favorites from the last few weeks. Not overly complicated, but tricky enough to require some thinking and exploration of various options to find an elegant and (somewhat) short solution.

Sp3000

Now I feel like porting my Python and seeing what that gets :P

Optimizer

form a smaller cage to a bigger?

Reto Koradi

@Sp3000 Hey, at least I was leading for a little while. :)

The overall logic does not look that different, as far as I can tell.

Sp3000

I wouldn't expect it to

Reto Koradi

Now that I think about it more, I should probably carry along the height of the previous book, instead of the whole string, while constructing the separating lines.

Transposing the whole thing was very obvious. After I really started thinking about a solution, it also seemed easier to simply drop the separating lines from the input, and reconstructing them at the end. Looks like you went the same way there.

Sp3000

07:24

Hm... I don't have that much better

Reto Koradi

I should be able to save a few bytes on the final loop. But it's time to go to sleep. I'll try another round of improvements tomorrow.

Thanks for all the tips.

New Main Posts

0

Q: Balance a set of weights on a seesaw

Balancing Act Overview Given an input of 3 single-digit integers representing a set of weights, output an ASCII representation of a seesaw with the weights placed on it so that it is in balance around a central pivot. Each number has a weight equal to its value. The torque of each number is th...

code-golf ascii-art physics

Sp3000

Posted. .\ is surprisingly more useful that I initialially joked it wouldn't be

For some reason [LL] [1 2 3]* doesn't do what I want it to do

... oh right, nvm

@samgak Nice challenge!

samgak

07:47

thanks

Reto Koradi

I initially also tried the final part with forming pairs using 2ew, and then looping over the pairs. But it got kind of messy. Particularly the combination of the result. Looks like that's what .\ solves for you. I tried with z, but then I got a nested list that would have need additional unpacking.

Lembik

09:37

hi all

how are the coding geniuses?

Optimizer

coding .. who?

2

ಠ_ಠ

Lembik

how do you think they provide the linux login at tutorialspoint.com/compile_c_online.php ?

is it easy to set up this service ?

I mean using free tools

@Optimizer :)

undergroundmonorail

11:58

thanks, opengl

New Main Posts

12:36

0

Q: More is still less and less is still more

So, this question is obviously inspired by this question posted this June by Dennis. The main task is the same, and the main criteria are similar: Your code must be at least 1 character long. Running the original code produces x characters of output to STDOUT (or closest alternative), where 0 ...

code-challenge source-layout

Rainbolt

13:08

This is part of the reason why I don't want to play DnD: rpg.stackexchange.com/q/65738

Every decision is like a mini election

I watched some guys play once and it took them an hour to get through a dark alleyway

aditsu

here's another reason not to play DnD :) chick.com/reading/tracts/0046/0046_01.ASP

Nathan Merrill

I've read a lot of tracts, but that one was too bizarre to even take seriously

aditsu

13:23

anyway, I know almost nothing about DnD, but what little I heard about it seems boring to a painful degree :p

Nathan Merrill

I've never played it, but its basically collaborative storymaking

Geobits

13:41

With random tossed in. I'm sure most storywriters don't typically roll a d20 to decide the fate of their protagonists.

"Ah, damn. Bilbo got a bad roll. I guess I have to change the name from The Hobbit now that he's out."

Nathan Merrill

how do we deal with this answer: codegolf.stackexchange.com/a/54321/20198

it technically works

Geobits

Does it? The output I'm seeing looks like it repeates the input instead of terminating.

Nathan Merrill

I downloaded it, opened it in excel, and pressed the button, and it drew a path

and only 1

also, can you flag a duplicate answer?

Geobits

Bah, ninja'd.

You should be able to flag dupe answers.

Nathan Merrill

I know

I'm going very low quality

because it is

Geobits

13:55

Oh, right. For straight dupes, it might be better to custom-flag. That way mods can instantly see the problem instead of trying to figure out if it's low quality enough. Of course, if it's also VLQ...

Nathan Merrill

also, is in-cell programming possible with excel?

(not macros)

and, if so, how do we judge it?

Geobits

I try to stay as far away from Excel as possible, so I'm not the guy to ask that :D

Nathan Merrill

if 20 cells all contain the exact same formula (simply referencing different cells), do we still count it 20 times?

Geobits

Dunno. Can't you write a function and just call it from each cell or something?

Nathan Merrill

maybe, but then you still are going to have 20 function calls

Geobits

13:57

I really don't know much about Excel programming. Clearly.

Nathan Merrill

oh, custom functions are defined as macros

Nathan Merrill

14:11

@Geobits there's a proposed edit by an anon user that technically improves the answer by adding the code

but 1. It adds code and 2. It doesn't explain it

Geobits

If it's the same code, that sounds better I guess (I haven't downloaded it to compare). Still not great, yea, but -probably- not delete-worthy.

Vioz-

I can go through and explain it if that'll make the answer better.

Lembik

hi all

I have yet another impossibly difficult counting puzzle up my sleeve :)

if anyone is interested

Vioz-

I'm interested :D

Lembik

hooray!

ok ..before I put it in the sandbox.. let me try out a version here

consider binary strings of length 2n

Geobits

14:23

Famous last words...

Lembik

for a given string S we output the number of 1s in every window of length n

so we give n+1 outputs (hmm.. maybe S should be of length 2n-1)

Vioz-

So a string S is converted to a binary string, split into sections of length 2n, count ones in each and print?

Lembik

sorry so

given two strings S1 and S2, we say they match if all the counts match

and we look at all n substrings of length n of it

there are n of these

for each substring we count the number of ones in it

Geobits

So far this sounds O(n)

Sp3000

I hear a "but then <super hard task>" coming

Lembik

14:26

oops

given two strings S1 and S2, we say they match if all the counts match

two counts match if one is within a multiplicative factor of 2 of the other

is that clear so far?

@Sp3000 it's coming..patience :)

Sp3000

Is this matching in order, or in terms of, say, a multiset?

Lembik

in order

for a given string you get an array of n numbers as the output

for two strings S1 and S2 we compare their two arrays in order

Sp3000

Are S1, S2 the same length? (just for input purposes)

Lembik

clear?

they are both of length 2n-1

Vioz-

n is given, or we math it out?

Lembik

14:28

it will be given.. well... patience :)

but let's say it is given

everything ok up to now?

Vioz-

Yep

Lembik

ok. so the question is this.. given an n, how large a set of strings of length 2n-1 can one make so that no pair of strings matches

that's it :)

so the input is n

and the output is an integer

everything in the middle is up to you :)

Sp3000

I'm assuming outputting the actual set would be good as well :P

Lembik

well yes but that might not be the best way :)

I think the sets can get very large

Sp3000

No, I just mean for verification purposes

Lembik

14:32

but for small n that is a great idea

Sp3000

Otherwise, how are you going to check the answers?

Lembik

yes

I think this makes both a nice golf and fastest-code question

my preference is always fastest-code of course :)

Sp3000

Sounds more like code-challenge than fastest-code to me

Lembik

oh right.. I suppose the winning criteria could just be the highest n you can compute

or the highest you can compute in 1 minute on my machine

depending on what people prefer

I am open to suggestions

both have disadvantages and advantages

Sp3000

I'd prefer the former because the latter has problems like picking good random seeds

Lembik

14:35

why do we need randomness?

Vioz-

Pick a starting value for the set to compare the rest to, I think

Lembik

I am a little lost. Why is this a problem? I mean any code you write that uses randomness will work just as well on my machine as on yours

of course the first challenge is to get the right answers for n = 1..5 :)

I also prefer the former as it allows people to use mathematica

but it does mean that people with slow computers are screwed

unless they are also much cleverer of course :)

@Sp3000 does it seem suitably super hard? :)

Sp3000

Do you know the optimal for 1 ... 5?

Lembik

no! I have code :)

but I never like to bet my code is right

Sp3000

I was assuming you had at least some brute force way of checking for small n

Lembik

14:40

yes absolutely

Dennis

@MartinBüttner {}s also is useful sometimes.

Lembik

brute force is not so hard

Martin Büttner

@Dennis ah, right, thanks

Sp3000

May I ask what they are? Or are you keeping that a secret?

Lembik

@Sp3000 you can just try all possible strings, compute all the arrays then solve max independent set using your favourite library

I used igraph

each node is an array and two nodes are connected if the arrays "match"

Vioz-

14:43

I think I have something figured out.

Lembik

@Vioz- cool!

Vioz-

Do you have any numbers I can check against for small n?

Sp3000

^^ that was what I was asking but I think Lembik misunderstood

Dennis

@MartinBüttner Any suggestion to shorten [UU] or [-2X]?

Sp3000

Also re randomness, I can pick a pseudorandom seed at will and know that my program will perform better with this seed than any other that I tested with, assuming I used randomness in the program

Dennis

14:45

Could use it for this answer. :D

Sp3000

But something makes me think there should be a deterministic way that's a lot simpler...

Lembik

@Vioz- this is bad but my coding computer is not here sorry.. I should have emailed the numbers to myself

I will get them to you as soon as I am back at the other computer

Vioz-

I think so, just from the first few small n it looks like there's an easy way to calculate this

Lembik

really??

@Vioz- that would be very clever!

Vioz-

(assuming the sets I can find are the actual maximum sets)

Lembik

14:47

how are you finding the maxima?

or is that secret? :)

Vioz-

I'm just doing a naive approach, starting the set from a string of zeroes of length 2n-1 and just iterating through all the binary strings possible at that length, checking them against what's already there

Lembik

oh I see

I am not sure that is guaranteed to be optimal

Vioz-

For small n it seems it might be, not sure about larger n

Lembik

what do you get for n = 5

?

Vioz-

270, which seems really big, so I may be approaching this wrong

as in the number of items in the set

Lembik

14:51

2^9 is only 512

that seems like a big number

Vioz-

Yup

but the output doesn't seem to have duplicates

in terms of matching by order

Sp3000

Did you do the multiplicative factor of 2 part?

Vioz-

Ah, I don't believe I did

Lembik

aha :)

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