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Basset Hound
Basset Hound
1:26 AM
What's the syntax for the CJam while loop (w)?
 
Dennis
Dennis
{condition}{block}w
0{_10<}{_p)}w; prints the numbers from 0 to 9.
 
Basset Hound
Basset Hound
Ah.
Thank you @Dennis
It freezes the online interpreter?
 
Dennis
Dennis
@AlexA. Makes sense. I wonder which one works in IE (if any).
 
Basset Hound
Basset Hound
Alright.
In while loop blocks, do things put onto the stack stay on the stack?
My code is giving me a no.
 
Alex A.
Alex A.
@Dennis I have a Windows VM on my Mac and the first thing I did when I set it up was uninstall IE. :D
 
Dennis
Dennis
1:36 AM
They do. But be aware that, after the first block is executed, one item is popped from the stack to check if it's truthy.
 
Basset Hound
Basset Hound
Alright.
 
Dennis
Dennis
@AlexA. Probably not an issue for a VM, but you can't install CorelDRAW without IE. I learned that the hard way.
 
Alex A.
Alex A.
What's CorelDRAW?
For whatever reason, Visual Studio also requires IE. It wouldn't let me finish the installation until I reinstalled IE. But I reuninstalled it after VS.
 
Dennis
Dennis
Graphic design software.
The CD installer requires IE to display the EULA. But doesn't say so. Just hangs.
 
Alex A.
Alex A.
Haha awesome.
if (browser.name != "IE") { wait(100000000000000000000000000000); }
 
Dennis
Dennis
1:44 AM
Yup, that was a fun afternoon.
 
Alex A.
Alex A.
Was it an urgent work-related venture or were you installing it for home use?
 
Dennis
Dennis
2:06 AM
For my sister in law. She's studying graphic design.
 
BrainSteel
BrainSteel
2:20 AM
I have been summoned in the most delightfully confusing manner.
 
 
1 hour later…
Dennis
Dennis
3:31 AM
Why is this challenge so unpopular?
-1
Q: Magic Square Challenge

SirParselotA magic square is a square where the rows, columns, and main diagonals all add up to some number n. Your Task Create a solver that given an unsolved square as a list and some number n on stdin will print the solved square as a list. You should be able to put any solvable square in it and get a...

code-golf
Three downvotes and one vote to close as too broad...
 
 
2 hours later…
Dennis
Dennis
5:07 AM
@RetoKoradi Yes, that's correct. I'm not sure what is going on there. As far as I can tell, the answer uses i for base conversion, which should downright refuse to interpret "15" as a base 5 number.
 
Reto Koradi
Reto Koradi
@Dennis My "solution" gives [3 8 10] for that input. But it doesn't handle the invalid cases at all, and is already 40 bytes. So I'll probably not finish it. At least it seems mathematically correct.
On the magic square: I didn't vote, but it's very confusing because it changed so many times. Maybe that's why people downvoted. At some point, it said that it would only have to deal with single "failures". Now it says again that it should solve all cases. Also, while that's probably insignificant, I don't understand why some numbers are bold in the output at the bottom.
 
Dennis
Dennis
@RetoKoradi Right now, it says with at most one wrong number in each row and column. The bold numbers are those that have been relocated.
 
Reto Koradi
Reto Koradi
Yes, I had just figure out the bold numbers.
 
Dennis
Dennis
That's probably worth adding to the question. It took me a moment to figure that out as well.
The edits pretty much left a mess, but I think the votes should be based on the current state of the question, not it's history.
 
Reto Koradi
Reto Koradi
Right, it does say "at most one number...". While I should have seen it, it would be nicer if it were listed as part of a clear input spec.
Your first version would work for all solvable inputs? Or only for the ones with at most one wrong number per row/column?
Well, I guess I could try it. :)
 
Dennis
Dennis
5:24 AM
Only for those.
 
Reto Koradi
Reto Koradi
Yes, doesn't seem to work if I swap two more numbers in the input.
Solving the "real deal" would be more interesting in some way. Not sure how efficiently it can be done. Might be more suitable for a performance challenge if there's no efficient way that is still reasonably easy.
 
Dennis
Dennis
I've made a few edits to highlight the things we talked about.
 
Reto Koradi
Reto Koradi
Thanks. That should help those of us who apparently have trouble reading long sentences. ;)
 
Dennis
Dennis
I have no idea how to approach the "real deal". A fastest code challenge would probably be interesting. 20x20 square, n entries in incorrect cells, solving for the highest n in x minutes wins.
It's pretty easy to overlook these things, especially if you've read the question before the edit.
 
Reto Koradi
Reto Koradi
That would be one option. I was thinking completely arbitrary order in the input, and solving for largest n wins.
 
Dennis
Dennis
5:34 AM
Or that.
I'm incapable of writing fast code, so I'm not very good at designing fastest-code challenges.
Exhibit A would be my rather broken domino tilings challenge.
Exhibit B, which nobody has even answered so far:
8
Q: Fastest Longest Common Subsequence Finder

DennisYour task is to solve the Longest Common Subsequence problem for n strings of length 1000. A valid solution to the LCS problem for two or more strings S1, … Sn is any string T of maximal length such that the characters of T appear in all Si, in the same order as in T. Note that T does not have ...

string fastest-code subsequence
 
Sp3000
Sp3000
Are answers like these allowed? I'm not that familiar with Javascript, but my understanding of this answer is that something like W3000 would fail
 
Reto Koradi
Reto Koradi
I enjoy solving them. Even though they are often very time consuming compared to golf challenges. I'm still fairly proud of this one: codegolf.stackexchange.com/questions/52193/…. n=156, after people initially posted solutions that made it to n=5. And the resulting number is about the number of atoms in the universe, squared.
 
Reto Koradi
Reto Koradi
5:55 AM
@Dennis Not sure why nobody went for that longest subsequence problem. I don't see anything bad about it. I think what stopped me (apart from probably having a few other half finished solutions to other performance challenges) was that it looked like it might be a fairly standard problem, where the best approach might be to look for literature, and implement a published algorithm. I don't know if that's actually the case, but I don't generally enjoy doing that very much.
 
Sp3000
Sp3000
^^ That's probably exactly why, actually
 
Dennis
Dennis
@Sp3000 I don't think they are. If your language can't handle arbitrarily long strings, that's one thing. But arbitrarily limiting the supported input to save bytes...
 
Sp3000
Sp3000
Hm... well I left a comment
I guess one of the major differences between PPCG and, say, anarchy golf is you can't do tricks like these since there's more than just a few set test cases
 
Dennis
Dennis
@RetoKoradi I haven't seen a lot about the LCS for n > 2 strings, so I hoped it would be a bit more difficult than that.
 
Reto Koradi
Reto Koradi
6:10 AM
@Dennis One thing that might help the challenge would be better test data. You show how to generate data, but for development people would probably want an example where they know what the correct result is, so that they can validate their algorithm. The two 6 letter strings are kind of minimal.
 
Dennis
Dennis
@RetoKoradi The problem is that there is no single correct result. At most, I could include the correct length of the output.
 
Reto Koradi
Reto Koradi
I think that would be very helpful already. Say an example with at least 3 strings of at least a few dozen characters. Enough to exercise an algorithm, and give reasonable confidence that it works correctly.
I guess another "minor" obstacle for me is that I don't know how to solve it... I'm slightly familiar with sequence alignment algorithms, and it sounds at least somewhat similar to that. But those already get much more complicated with more than 2 sequences, as far as I remember.
 
Sp3000
Sp3000
The standard dynamic programming LCS can be extended easily, but it explodes with the number of dimensions
But yeah, there should be a lot in the literature about multiple LCS/multiple alignment ... that sort of thing
 
Lembik
Lembik
7:05 AM
hi @Sp3000
 
Sp3000
Sp3000
Hi Lembik
 
Lembik
Lembik
what I like about ppcg is that no one seems to sleep :)
3
 
Sp3000
Sp3000
Yeah, about that...
 
grovesNL
grovesNL
Instead of sleeping at 2am it seems like a great idea to work on my own Code Golfing language. Why...
2
 
Peter Taylor
Peter Taylor
7:49 AM
@Dennis In an ideal world. But despite the recent comments, most participants in the site do sleep, and don't spend all of their waking hours on PPCG, so even if the downvoters do feel that the raft of edits have rescued the question you should expect some delay before they change their votes.
 
New Main Posts
New Main Posts
8:11 AM
-1
Q: Selection problem

Shobit MahajanA Grandpa hits his kid with following problem: His grandpa tasks him with a problem - he says that he will give him as many candies as he wants (N) of all distinct flavours for as many students in his school (K) if he can tell him the sum of the following: 1 The number of ways there are to choos...

java
 
Sp3000
Sp3000
^^ Super speedy Martin
 
Optimizer
Optimizer
^^ You should really sleep
 
Sp3000
Sp3000
Who should?
 
Lembik
Lembik
of course what people should really be doing is posting answers to codegolf.stackexchange.com/questions/54354/… :)
 
Sp3000
Sp3000
8:31 AM
Not with such a lame brute force
 
Lembik
Lembik
@Sp3000 isn't your method a little cleverer than naive brute force?
I say that because it is much much faster than my brute force
 
Sp3000
Sp3000
It's just generates all strings to give a list of possible vertices, then recursive backtracker on the following: Pick first vertex, keep mismatches
I'd call that naive brute force :P
 
Lembik
Lembik
well my version runs "max independent set" from a library
and is very very slow :)
I can't do n = 5!
so you are definitely winning :)
 
Sp3000
Sp3000
I can't either, the numbers I've been saying are intermediate outputs
 
Lembik
Lembik
9:11 AM
good point
 
Peter Taylor
Peter Taylor
I can get an easy conjectured upper bound based on a conjectured independence number of a tensor power of a graph. But the actual graph obtained is a subgraph of the tensor power G^n where G is the graph of matching single-element vectors, and it's not obvious how that will affect the independence number.
 
Lembik
Lembik
@PeterTaylor for my puzzle?
 
Peter Taylor
Peter Taylor
Yes
 
Lembik
Lembik
cool!
how high is the upper bound?
I mean how does it grow with n?
 
Peter Taylor
Peter Taylor
\alpha(G)^n
It's not a closed form, but it reduces the independent set calculation to a much smaller graph.
 
Lembik
Lembik
9:13 AM
how does alpha G scale?
oh I see
this could be useful for people doing some sort of optimization so they have a feeling for how far they might be from the optimum
as well as just being interesting in its own right
 
Beta Decay
Beta Decay
10:06 AM
@Geobits Do you mind if I go ahead with this?
3
A: Sandbox for Proposed Challenges

Beta DecayIs it a bird, is it a plane? code-challenge image Challenge Supplied an image, you must determine if the subject of the image is a bird, a plane or Superman. Further information All images will be the objects in flight. The images of planes and birds will be against blue backgrounds (in som...

 
Martin Büttner
Martin Büttner
@BetaDecay do you have those 30 pictures yet?
 
Beta Decay
Beta Decay
10:18 AM
@MartinBüttner Ugh, I can't believe I forgot that :P
 
New Main Posts
New Main Posts
0
Q: Cryptic Kicker //

Dhruv RamaniCryptic Kicker A common but insecure method of encrypting text is to permute the letters of the alphabet. In other words, each letter of the alphabet is consistently replaced in the text by some other letter. To ensure that the encryption is reversible, no two letters are replaced by the same le...

code-golf cryptography
 
trichoplax
trichoplax
@BetaDecay I don't know for certain but this sounds fairly different from @Geobits' sandbox post despite the similar concept. Yours sounds like it has much more opportunity for little heuristic tricks, rather than being a full recognition challenge. I'd expect them to be interesting in sufficiently different ways to not be duplicates (not my decision though - ask around...).
 
Beta Decay
Beta Decay
@trichoplax Oh okay. I'll see what other people have to say just to be sure
 
Peter Taylor
Peter Taylor
10:47 AM
@BetaDecay I don't get the point. The Superman ones can be identified by testing whether the background is white, so they're trivial to distinguish. The interesting bit is distinguishing birds from planes, but that's the part which is furthest from the window-dressing of the question.
And IMO blind classification questions should get closed for lacking an objective scoring method.
 
Beta Decay
Beta Decay
@PeterTaylor I realised that identification of Superman is trivial, but I kept it to keep a theme in the question
 
Peter Taylor
Peter Taylor
I guessed that. But if it's a choice between a strong theme or a good question, it's worth sacrificing the theme.
3
 
Beta Decay
Beta Decay
11:03 AM
What would a good replacement for the Supermen be then? Helicopters?
 
Peter Taylor
Peter Taylor
Birds vs planes could be a good question with a good scoring method.
 
Beta Decay
Beta Decay
Oh okay. So you're saying that the scoring method I have now should change?
 
Peter Taylor
Peter Taylor
Yes. I should be able to tell whether my answer is better than the existing ones before I submit it.
 
Beta Decay
Beta Decay
I see. So that could be remedied by allowing people to see the test images.
 
trichoplax
trichoplax
11:20 AM
This does now mean that the question is nearer to duplication with @Geobits' sandbox question.
 
Beta Decay
Beta Decay
Tricky...
 
 
1 hour later…
orlp
orlp
12:43 PM
lol
 
BrainSteel
BrainSteel
12:57 PM
@Dennis Do not despair! I'm working on improving my fastest longest common subsequence code. Hopefully I can come up with something clever, it's not ready yet :D
 
New Main Posts
New Main Posts
1:24 PM
0
Q: GolfScript, CJam, or Pyth?

TreFoxI'm not really sure if this is on topic, as it isn't really specified, but I thought I would ask it here anyways. Which is better, Pyth, CJam or Golfscript? In asking this, I do not mean which has a prettier syntax or which has the most useful commands, I mean overall, which one is usually the ...

golfscript pyth cjam
 
Doorknob
Doorknob
^ oh I am totally going all science on this one, with the data dump
 
orlp
orlp
@Doorknob to complement you, good sir, I gave my random guess without any data to back it up in the comments :)
 
Sp3000
Sp3000
1:47 PM
Hm... I'm not sure how to feel about this comment...
 
Pietu1998
Pietu1998
The first solution I came up with for Cryptic Kicker only requires 10^4 yottabytes of memory. Looks good.
 
Sp3000
Sp3000
@trichoplax Might want to award that bounty to orlp before it auto-awards half the amount :P
 
Sp3000
Sp3000
2:10 PM
@Dennis @Doorknob I thought so... I wasn't exactly sure what to say, but I'd have preferred these types of questions be asked in chat
I'm not sure how you guys feel about the on-topicness of the question though
 
Martin Büttner
Martin Büttner
It's not really answerable, is it?
 
Doorknob
Doorknob
It's answerable: 
golfscript is shorter than pyth 6 times (~13.043%)
golfscript is shorter than cjam 16 times (~20.513%)
pyth is shorter than golfscript 39 times (~84.783%)
pyth is shorter than cjam 59 times (~60.204%)
cjam is shorter than golfscript 57 times (~73.077%)
cjam is shorter than pyth 31 times (~31.633%)
Looks like Pyth is the winner.
 
Sp3000
Sp3000
I'm more concerned about the fact that whatever answer's given will be completely outdated once Pyth, CJam continue development
 
Dennis
Dennis
I don't either. I think that if asking for golfing advice is on topic (which I still do not agree with), questions like this one should be too.
 
Martin Büttner
Martin Büttner
@Doorknob what about challenges that don't have answers in more than one of the languages? there could be a lot of selection bias. and who says the submissions are particularly well golfed?
it's also completely ignoring that APL and J can be very competitive
 
NicoA
NicoA
2:15 PM
Thanks for the scientific analysis Doorknob :P
 
Doorknob
Doorknob
@MartinBüttner Yeah, it's definitely not perfect. I only chose challenges that had answers in at least two of the languages in question though, and the fact that there are percentages makes that point moot anyway.
I threw in J as an experiment. Even GolfScript handily beat it.
 
Martin Büttner
Martin Büttner
@Doorknob "I only chose challenges that had answers in at least two of the languages in question though" that's my point.
There might be certain types of challenges where the other two languages don't ever bother trying.
 
Doorknob
Doorknob
APL seems to be > GolfScript though.
@MartinBüttner Ah, I see. Yeah, again, not perfect, but overall Pyth seems to perform better.
 
Sp3000
Sp3000
There's a lot of challenges where one of the two is clearly better, and nobody tries the other language
 
Doorknob
Doorknob
As a general-purpose language, I guess you could say. 
golfscript is shorter than ostrich 1 times (~100.0%)
pyth is shorter than ostrich 1 times (~100.0%)
cjam is shorter than ostrich 1 times (~100.0%)
ostrich is shorter than golfscript 0 times (~0.0%)
ostrich is shorter than pyth 0 times (~0.0%)
ostrich is shorter than cjam 0 times (~0.0%)
:'(
 
Sp3000
Sp3000
2:19 PM
Ostrich only lost to CJam by 1 question!
3
[/bad statistics]
 
NicoA
NicoA
@Doorknob is ostrich the golfing language you are developing? (Kinda new here :P)
 
Doorknob
Doorknob
@NicoA Not really developing it anymore, but yes.
 
NicoA
NicoA
Yeah, I tried to develop my own golfing language, I abandoned it because it was just never beating anything.
So I know now that Pyth is the shortest, but do you think it should be the one I learn? I mean, I have never really messed with "golfing languages" before, and I am afraid I will go into this and not understand any of it. Any prerequisites for learning Pyth? (Besides, obviously, knowledge of Python)
 
Doorknob
Doorknob
I'm no Pyth expert, but I'm pretty sure you can learn Pyth without knowing Python.
 
steveverrill
steveverrill
@Orlp: "I'm more concerned about the fact that whatever answer's given will be completely outdated once Pyth, CJam continue development" I see absolutely no problem with that, provided the answer is dated, which it will be. I think it would be interesting to come back in a few years time and see if it needs revision.
 
Sp3000
Sp3000
2:24 PM
You can learn Pyth without knowing Python, but knowing Python sometimes helps understand why things work the way they do
 
NicoA
NicoA
Oh thats awesome! I know Python, but not that deeply. I'm more of a Lua guy.
 
Dennis
Dennis
@BrainSteel Does it handle at least two strings? If so, please post it. Might kickstart the question.
 
Martin Büttner
Martin Büttner
@NicoA I think CJam is the more fun language, but that's obviously personal preference ;)
 
steveverrill
steveverrill
@Doorknob, your data is very interesting. If you feel chat is the best place I won't argue, but I encourage you to post it as an answer to that question (and my preference was to leave it where it is)
 
NicoA
NicoA
Oh ok, so I shouldn't delete the question?
@MartinBüttner I don't think programming Cjam, Golfscript, Pyth or any of those wil lever be as fun as an actual language with syntax. I mean, when I look at some of those answers it seems like someone just banged their head against a keyboard repeatedly...
 
Sp3000
Sp3000
2:28 PM
@steveverrill I'm assuming that ping was for me, but I just thought that this type of question is best discussed, and I'm not sure SE's the best place to do that (I could imagine the comments getting long)
 
Dennis
Dennis
@NicoA Are you @TreFox?
 
NicoA
NicoA
@Dennis Yeah, this is my younger brothers account which I have no idea how to log out of.
 
Martin Büttner
Martin Büttner
@NicoA how come? I personally think it's more fun than programming in "an actual language". CJam is stack-based, and switching to an uncommon paradigm makes you think outside the box much more than you usually have to.
if it wasn't more fun, then why would you bother learning it? winning code golf contests really isn't that important ;)
 
Dennis
Dennis
Personally, I love stack-based languages. They are written and executed in reading order.
 
NicoA
NicoA
@MartinBüttner Well, I guess I'll have to give it a shot before making judgements, I just feel like I don't want to be limited by not actually understanding any of the code I write
Although I guess it becomes much more readable once you know the language well enough
 
Martin Büttner
Martin Büttner
2:30 PM
@NicoA any language is illegible until you learn it ;)
 
Sp3000
Sp3000
@NicoA All golfing languages look like gibberish before you learn it. Once you do learn it it still looks like gibberish... with structure.
3
It's a bit like learning a foreign language, adding a new word to your vocab and going "Oh q~? I know what that means!"
 
BrainSteel
BrainSteel
@Dennis I'm going to test my solution on your random script (I'm not so hot with scripting, still figuring it out) some more. It's derived from that golfed code, so it is in dire need of some prettiness, too. Hopefully I'll have something worth posting by the end of the day.
 
NicoA
NicoA
@Sp3000 Now I want to create a country where everyone speaks CJam...
Btw, does anyone know how to log out in chat? I'm stuck on this account and chat.stackexchange.com/logout doesn't do anything for some reason...
 
Dennis
Dennis
If nothing else helps, delete some cookies.
 
NicoA
NicoA
I think the problem is that this account was actually deleted... but someone it still survives in chat
If you go to my profile and click my parent user the page can't be found
*somehow
 
Dennis
Dennis
2:36 PM
So that's while your profile gives a 404.
 
Doorknob
Doorknob
Yeah, what's weird is that your PPCG account is linked to the account you're currently chatting on though.
 
Dennis
Dennis
Which browser are you using?
 
NicoA
NicoA
Chrome
Wow... how did my younger brother rack up 1.8k rep :O
 
BrainSteel
BrainSteel
It seems like this recent CJam vs Pyth vs GS question has sparked quite the kerfuffle. Personally, I consider it in league with tips questions, but perhaps we should make an answer to the relevant meta question for a clear consensus?
 
NicoA
NicoA
Yay I sparked a kerfuffle

I always wanted to do that
 
Doorknob
Doorknob
2:37 PM
@Dennis It's not a browser issue. It's something wrong with how SE handles chat / main accounts when dealing with account deletion. (We had a similar issue before with Calvin's sock.)
 
NicoA
NicoA
How did they get rid of calvin's sock?
 
Sp3000
Sp3000
... I think I might have been okay with the question if it was a bit better specified
"Usually the shortest" seems quite broad
 
Doorknob
Doorknob
Oh hey chat's about to go down for a few minutes.
 
NicoA
NicoA
In what way? I can edit it
 
Martin Büttner
Martin Büttner
nooooo, chat outage imminent... can't breathe...
 
BrainSteel
BrainSteel
2:38 PM
How will we survive?!
 
NicoA
NicoA
I'm going to go huddle in a corner and pray for mercy while its out.
 
Sp3000
Sp3000
Maybe something like comparing the languages and asking why and when one language does better than another
... that was a short outage
 
BrainSteel
BrainSteel
I feel the question primarily boils down to this: As a community, do we want questions about comparisons of programming languages as they are relevant to the challenges on this site?
 
Doorknob
Doorknob
aaand we're back!
 
NicoA
NicoA
@Sp3000 None of them are really specialized to a certain area though, so would there really be a "When does Pyth beat CJam" ?
 
Peter Taylor
Peter Taylor
2:45 PM
@BrainSteel Regardless of the consensus about that point in principle, questions for which the only available answers are speculation are not on topic on any SE site.
 
NicoA
NicoA
:(
I'm going to go delete some cookies and try to get myself out of this account
 
Doorknob
Doorknob
@NicoA hang on a second, I think I found the problem
 
NicoA
NicoA
Ok, I'll be fine with whatever you do to this account
Test
 
Doorknob
Doorknob
I changed your parent site to PPCG. Now at least your parent site link isn't 404'ing.
 
BrainSteel
BrainSteel
@PeterTaylor Solid point. However, I think the question could be posed to remove the speculation. @Doorknob showed that we have objective data that can be used to answer these kinds of questions.
 
TreFox
TreFox
2:48 PM
Ok, now when you click on my account it takes you to TreFox, but I still display as NicoA. Do I have to do something else to get my actual name to show up?
 
Doorknob
Doorknob
@TreFox try refreshing the chat page
 
Martin Büttner
Martin Büttner
@TreFox you show up as TreFox now
 
TreFox
TreFox
Oh wait, I'm TreFox now. Thank you!
 
Doorknob
Doorknob
@BrainSteel Well, as @MartinBüttner mentioned, the data is far from accurate anyway. It's just a general... guess in the right direction, really.
 
Dennis
Dennis
I've logged out of chat and now I can't get back in. :(
 
TreFox
TreFox
2:48 PM
How could a deleted account still be able to talk in chat though?
 
Doorknob
Doorknob
Main site is down now.
 
TreFox
TreFox
@Doorknob I think that is the most useful site I have ever seen
 
BrainSteel
BrainSteel
@Doorknob True, it is not necessarily good data.
 
Sp3000
Sp3000
@TreFox Whenever Pyth has a builtin which CJam doesn't is a good starting point
 
TreFox
TreFox
"*Advice may be invalid due to caching" xD
 
Doorknob
Doorknob
2:50 PM
@TreFox :D
 
Sp3000
Sp3000
@trichoplax Why the accept?
 
TreFox
TreFox
I'm not an expert at any web stuff but a quote from some guy who works at the stack exchange (Yes I peer into my brothers email account every once in awhile. Mostly for espionage reasons but we won't get into that), "We have had no choice but to delete all records of your account from the stackexchange"
 
Doorknob
Doorknob
Huh what? I've never heard of anything like that having to happen.
 
TreFox
TreFox
He was too young for the stackexchange
 
Doorknob
Doorknob
Oh, that makes sense then.
 
TreFox
TreFox
2:53 PM
Luckily I just passed the age barrier :D
 
BrainSteel
BrainSteel
We have an age limit?
 
TreFox
TreFox
Because of the Childrens Online Protection Agreement they are not allowed to collect any data (Email, name, etc.) From children under 13.
 
Doorknob
Doorknob
@BrainSteel Yes, for legal reasons.
 
TreFox
TreFox
There is a meta thread about it, I'll try to find it.
 
Doorknob
Doorknob
Main site now in read-only.
 
TreFox
TreFox
2:54 PM
Why are they moving their database?
 
Doorknob
Doorknob
 
BrainSteel
BrainSteel
Ah, thanks for the references! Makes sense.
 
TreFox
TreFox
@Doorknob Colorado? I fear their database will die of boredom.
 
Sp3000
Sp3000
And we can write now, whee.
 
Doorknob
Doorknob
Back out of read-only.
 
TreFox
TreFox
2:57 PM
Oh and @Doorknob what happened to your background?
 
Doorknob
Doorknob
My what?
 
TreFox
TreFox
Your profile picture background. It used to be purple (or maybe green, can't remember) didn't it?
 
Doorknob
Doorknob
Oh, haha, yeah, this was the original version though.
 
TreFox
TreFox
What is the difference between the "hot" and "active" tab?
 
trichoplax
trichoplax
@Sp3000 If you didn't want bounty and acceptance, why did you post a shorter string? :P
 
Sp3000
Sp3000
3:07 PM
Well I think accepting only a few hours after an improvement has been made seems a bit fast, since orlp appears to be still trying
I won't question the bounty though, that part doesn't matter
 
trichoplax
trichoplax
@Sp3000 I did remember what you said about the bounty, and weighed my decision carefully, but I decided that since your latest string started from scratch at length 500, and since you've made impressive improvements, I wanted to award the bounty to your answer.
 
Sp3000
Sp3000
For which I thank :)
(although I haven't made that many improvements though)
 
trichoplax
trichoplax
@Sp3000 Oh - the acceptance tick I didn't put any thought into. It's had over a week so I accepted the top of the leaderboard. It will be changed back and for as C++ and PyPy battle it out ;)
 
Sp3000
Sp3000
I dunno, maybe it's just me but I like my "accept answer after <some time period>" to start counting from the last non-trivial answer edit
 
trichoplax
trichoplax
I don't know if it affected everyone, but where I am the site went down with 20 minutes left to award the bounty - it came back up just in time to avoid the amount being halved...
 
Sp3000
Sp3000
3:15 PM
Yeah I thought you might have been trying :P SE was doing stuff ^^ see a little bit back in chat
 
trichoplax
trichoplax
@Sp3000 I would follow that approach if I was going to assign a final acceptance, but I posed this question hoping for open ended improvements, so I'll leave it assigned and switch if new answers/updates come in.
 
randomra
randomra
@Sp3000 on the maze exit challenge did you try to have a fitness function for the strings or do you only deal with perfect (i.e. correct) solutions?
 
Sp3000
Sp3000
My very first attempt was a GA where the fitness function was the number of mazes solved. It did pretty terribly
 
randomra
randomra
only because of speed or otherwise too?
 
Sp3000
Sp3000
This one only deals with solutions which solves all mazes, but since some essential mazes are left out they're not quite perfect (although I've only ever seen at most 12 errors)
I'm not sure what fitness function I'd add tbh
(and yeah not having to count the total number solved helps a lot for speed)
(although mine hasn't been optimised with speed in mind as well as orlp's has :P)
 
randomra
randomra
3:26 PM
mazes solved seems to be good fitness function, but you might not want to check all, just sample it
if that makes sense in your implementations
 
Sp3000
Sp3000
The problem with mazes solved is that most mazes are really easy, and it's the few hard ones at the end which ruin everything
My current one only deals with one string though, so it's less of a GA and more of a random walk
 
randomra
randomra
so you think a string which solve 90% of the mazes helps almost nothing to find one which solves 100%?
 
Sp3000
Sp3000
It depends which 90% is solved
 
randomra
randomra
the easy part
 
Sp3000
Sp3000
If you sample uniformly, then yes it wouldn't help much
 
randomra
randomra
3:30 PM
hill climbing/random walk is often disappointingly effective compared to GA... :/
 
Sp3000
Sp3000
Yeah hill climbing was very disappointing :( Are you trying?
 
randomra
randomra
no, I don't have time in the next weeks, I'm just thinking :)
and reading, this and the game show questions are both fun
 
Sp3000
Sp3000
To put it in perspective, NESWSEENWNWSSWNNEENWWSESESWWNNESESNNE solves 93% of the mazes
That's length 37.
 
randomra
randomra
I see, but it still could be a useful core for the 100% solution despite their length difference
 
Sp3000
Sp3000
Hmm not sure about that... that one's from a greedy algorithm, which would solve all the easy ones first. This would mean that all the mazes with long or tricky solution paths are left, and I'm not sure 40 or so moves is enough to solve them all
 
randomra
randomra
3:51 PM
the 37 length string should be broken up with insertions but that would mean a big temporary decrease in fitness, maybe adding weights to mazes based on difficulty could help but that might be a bit too complicated to actually work
 
Sp3000
Sp3000
Well it might work for all you know :P Sounds like it'd help a lot over the naive approach at least
 
randomra
randomra
the advantage of just thinking and not doing :), you mean the naive fitness-based version?
 
Sp3000
Sp3000
Well the naive #number of mazes version, yeah
I'm just thinking and not doing atm as well :P
79's looking really likely to me atm, but I'm not sure how long it'll take to get it
 
trichoplax
trichoplax
Or who'll get it first :P
I didn't expect to see C++ and PyPy neck and neck like this. It's interesting
 
Sp3000
Sp3000
I'd try seeding orlp's solution with an 80 and seeing what happens but I'm not sure how
 
trichoplax
trichoplax
4:09 PM
Just needs a standard vector of 0,1,2,3 instead of N,S,E,W
I'd have tried myself but I'm trying to focus on the Computer Graphics private beta for the next week or so
 
Martin Büttner
Martin Büttner
huh, somehow I was unable to log into chat for the past 20 minutes or so
 
trichoplax
trichoplax
Just need to check which number goes with which direction
@MartinBüttner I had that earlier when main went offline
 
Martin Büttner
Martin Büttner
it was probably related to that
 
trichoplax
trichoplax
Made me panic as I had a bounty with minutes left before disappearing...
 
Sp3000
Sp3000
4:25 PM
@trichoplax Got it, thanks
 
Dennis
Dennis
5:01 PM
@MartinBüttner You too? I've deleted all cookies and local stotage and still couldn't. Maybe it will work now.
Yes! I'm back!
(On my desktop, that is.)
 
randomra
randomra
5:39 PM
@Sp3000 if there was a fixed goal cell it would be fun to find sequences by hand as you can visualize the superimposed states of all remaining labyrinths pretty well after a prefix is given in
it could work with the current setup too but less nice and clear the superimposed situation is
it's like a labyrinth game with (somewhat) invisible walls and multiple heros (controlled together)
 
New Sandboxed Posts
New Sandboxed Posts
0
A: Sandbox for Proposed Challenges

jimmy23013The hue of a color You are given the RGB values of a color. Your task is simple: to calculate the hue, in the simplest definition. Say the channels with highest, middle and lowest value are X, Y, Z (which are either red, green or blue) and their values are x, y, z. The hue of this color is (h(X...

 
trichoplax
trichoplax
6:25 PM
@randomra That sounds like an interesting challenge too. Finding strings that get all the heros to the destination without killing any of them.
 
randomra
randomra
6:41 PM
@trichoplax there must be a flash game like this
 
Optimizer
Optimizer
 
Vioz-
Vioz-
7:11 PM
@aditsu Do you remember where you got that watch from? I talked to a few people and asked about it, they seem to think it was either given away/sold at a trade show or sold internally
 
Lembik
Lembik
8:07 PM
hi @Vioz- @Sp3000
@PeterTaylor am I right in thinking that all your answers for n >= 6 may not be optimal?
@PeterTaylor amazing answer by the way!
 
Peter Taylor
Peter Taylor
@Lembik I make no guarantees about optimality.
 
Lembik
Lembik
we know the first 5 are optimal
 
Peter Taylor
Peter Taylor
To be precise, the greedy algorithm is known to approximate to within a certain ratio which depends on other properties of the graph, and I can't be bothered to look up the details and work it out.
 
Lembik
Lembik
@PeterTaylor do you have any feeling for how the value scales?
it's hard to guess by plotting it
ah another value :)
 
Peter Taylor
Peter Taylor
By eye it looks subexponential, but it's not something I have an intuition about.
The number of vertices in the graph definitely grows exponentially (there are easy lower bound of 2*3^n and upper bound of n*3^n), but the size of the cliques in G grows too.
 
Lembik
Lembik
8:28 PM
@PeterTaylor if you plot it on logscale it looks subexponential as well
but how knows.. it might be subpolynomial too?
 
Peter Taylor
Peter Taylor
8:45 PM
Nah, there are easy polynomial lower bounds. A linear lower bound is completely trivial, and a quadratic one isn't much harder.
 
Alex A.
Alex A.
9:25 PM
@Vioz- Out of curiosity, why is there a trailing dash on your username?
 
Vioz-
Vioz-
I don't remember, exactly.
 
Alex A.
Alex A.
Is there a meaning behind "Vioz"?
 
BrainSteel
BrainSteel
It's clearly "Zoiv" backwards.
 
Alex A.
Alex A.
If you rearrange the letters in "Peru," you can spell "Europe."
 
BrainSteel
BrainSteel
Well, you can get at least to "Eurp." Which is basically the same.
 
Alex A.
Alex A.
9:32 PM
"Urep" is phonetically close.
 
BrainSteel
BrainSteel
That's Peru backwards! The conspiracy unfolds!
 
Alex A.
Alex A.
Illuminati confirmed.
 
BrainSteel
BrainSteel
Peru is four letters long... But is only one country. 4 - 1 = 3. HL 3 confirmed.
 
Alex A.
Alex A.
Aw shit. GabeN is getting tricky naming countries.
 
Martin Büttner
Martin Büttner
10:02 PM
@Dennis Awwww, thanks for mentioning Retina in your language comparison :D
 

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