Ordered creative solution for Xs and Os Referee by veky - python coding challenges

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Ordered solution in Creative category for Xs and Os Referee by veky

def checkio(r):
    p = map(int, "093193293094272")
    r.extend("".join(r)[next(p):next(p):next(p)] for _ in range(5))
    return {t*3 in r: t for t in "OX"}.get(True, "D")

Sept. 14, 2013

Comments:

JuliusArcanum on Dec. 8, 2013, 4:42 p.m.
Nope.. sorry man, but it is definetly impossibru for me to understand your code. So I guess it is a great solution. ^^ Good job. (May I ask : Is there a web site I can learn all this stuff you use on your code?) Thanks.

veky on Dec. 8, 2013, 8:36 p.m.
The only important thing is: do you want to understand? If yes, and you are willing to invest some time, you will understand it. Web site? Of course. docs.python.org :-]]

apogeum on Feb. 7, 2014, 3:32 p.m.
WOW. Such algorithmic.

veky on Feb. 7, 2014, 5:21 p.m.
Since you didn't give me a thumb, I'll assume that was sarcasm. :-] Yes, hardcoding positions of all lines isn't very nice. But the point that all of them are in fact slices might be interesting. And getting True key from dict... I'll suppose you've never seen dict used as a select (quasideterministic if/elseif/else). :-)

s_prapat on March 6, 2014, 7:53 a.m.
I love it. :) Bending my mind. Normally I code straight to make it easy to be understood by others. But I love to spend time to understand codes like yours. good and lazy way to create an int array. hahaha like it.

veky on March 6, 2014, 8:16 a.m.
Thank you. I'm glad I could help you with mental gymnastics. :-)

bsquare on Aug. 29, 2019, 10:13 a.m.
I agree with that, your solutions needs usually gymnastics, and it is nice!

apogeum on Feb. 10, 2014, 3:23 p.m.
No man. No sarcasm. We use this doge comments in my team so often, that I forgot how it may sound :) I am a newbie to Python and any other top solution i see, I'm totally amazed seeing these constructs and how easily they read. No thumbs up yet as I need to digest Python's idioms a bit more to be able to say what's good and what's not. Hope you understand.

spoty on July 6, 2014, 8:08 p.m.
Yep nice again, I'm getting inspired by you more and more :)

veky on July 6, 2014, 8:37 p.m.
Glad to help. :-)

kryksyh on April 12, 2015, 9:28 a.m.
Well, I'm getting a collection of bookmarks in "i should elaborate on this later" folder :)

veky on April 12, 2015, 10:11 p.m.
People in 21th century still use bookmarks? And you really find the time to go through them later? Wow. :-D

kryksyh on April 13, 2015, 10:37 a.m.
<blockquote> People in 21th century still use bookmarks? </blockquote> Yep, and it's better not to say what browser I'm still using. :) <blockquote> And you really find the time to go through them later? </blockquote> I hope so, and sometimes I really do.

veky on April 13, 2015, 10:51 a.m.
<blockquote> Yep, and it’s better not to say what browser I’m still using. :) </blockquote> Netscape?! :-DD

ale1ster on June 24, 2015, 3:43 p.m.
<h2>(This is a comment)</h2> I happen to like this :D

veky on June 24, 2015, 4:01 p.m.
<h1>Ceci n'est pas un comment.</h1> Python is not Markdown. :-P

hrvoje on July 2, 2015, 1:24 a.m.
I'll try. First, he creates an iterator by mapping int to a string. (list added just for show): <pre class='brush: python'>In [19]: list(map(int, "093193293094272")) Out[19]: [0, 9, 3, 1, 9, 3, 2, 9, 3, 0, 9, 4, 2, 7, 2] </pre> Then, he cleverly extends the game board list (which already contains the rows) by adding columns and diagonals. He does it by joining all the rows in a big string and applying slice notation [start:stop:step] which changes with every loop pass by repeatedly calling next( p). To illustrate: <pre class='brush: python'>In [20]: [next(p), next(p), next(p)] Out[20]: [0, 9, 3] In [21]: [next(p), next(p), next(p)] Out[21]: [1, 9, 3] </pre> After extending, the dictionary looks like this: <pre class='brush: python'>In [22]: r Out[22]: ['X.O', 'XX.', 'XOO', 'XXX', '.XO', 'O.O', 'XXO', 'OXX'] </pre> Finally, he uses dictionary comprehension to create a dictionary with boolean keys defined by testing 3*'X' (or 'O') in list. <pre class='brush: python'>In [23]: {t*3 in r: t for t in "OX"} Out[23]: {False: 'O', True: 'X'} </pre> Then he calls get(True) with an optional argument what to return if get cannot find the droids he's looking for. Oh wait, that was from a different sci-fi movie :)

veky on July 2, 2015, 4:31 a.m.
<blockquote> Oh wait, that was from a different sci-fi movie :) </blockquote> You, sir, have a one weird mind. :-D

hrvoje on July 2, 2015, 9:49 a.m.
Coming from you, that's a huge compliment. :P

veky on July 2, 2015, 12:13 p.m.
That's a huge something, yes. But only you would call that something a compliment. :-)

quesneljoseph on Oct. 4, 2017, 1:09 a.m.
Thank you for this explanation. I am reading the python docs and its helping a ton to read this. im really weak in dictionary notation. Why use t for t in "OX" and not just list O or X? Sorry i am very new

veky on Oct. 4, 2017, 11:08 a.m.
The only problem is you're parsing it wrong. :-) It's not really ...something..., and then a colon, and then 't for t in "OX"', but in fact (something : t) for t ... -- that is, for each t in "OX", one key-value pair is inserted in a dictionary. Key is whether t*3 is in r, value is just t. Unraveled, it is <pre class='brush: python'>{'OOO' in r: 'O', 'XXX' in r: 'X'} </pre> The coding pattern is the classical <a href="https://stackoverflow.com/questions/14118996/is-switchtrue-valid-javascript">switch on true</a> idiom, only written in Python, where we use dicts to emulate the switch. :-D [So, in a way, dict comprehension is playing the rôle of metaprogramming.:] I hope it's clearer now. ;-)

quesneljoseph on Oct. 4, 2017, 9:23 p.m.
Thank you, you are completely right. I looked up dictionary and did a few problems using the notation to familiarize myself. Its remarkably clear to me now. Blows me away that you can use the comprehension in such a concise way. the .get method and dict comprehension is just so concisely used for its purpose here. i would have written (if i had the concept) <pre class='brush: python'>return {t*3 in r: t for t in "OX"}.get(True, "D") </pre> as <pre class='brush: python'>a = 'XXX' in r b = 'OOO' in r c = 'O' d = 'X' e = {a:d, b:c} return e.get(True, "D") </pre> A whole 5 freaking variables plus its not as satisfyingly generalized as yours. Man this is really inspirational, thank you for your comment :)

veky on Oct. 5, 2017, 4:26 a.m.
Don't think of them as "variables", think of them as "names". You don't need to name everything. And it's usually counterproductive if your names are semantically empty. "Here, put this notebook on the cabinet down the hall." is much clearer than "Call this notebook Emma. Call the house we're living in Sam. Call Sam's hall Jenny. Call the cabinet inside Jenny, Wanda. Now, put Emma on Wanda." ;-D

mithilkotak on Sept. 19, 2022, 5:42 a.m.
Thank you so much for this explanation.

amaciel81 on Dec. 22, 2016, 6:23 p.m.
Not that I could have thought about this all by myself, but you are right: 30 minutes and a couple of visits to docs.python.org are enough to put it together. Thank you, I learned a couple of new tricks and new uses for the old ones. :-)

veky on Dec. 23, 2016, 11:02 a.m.
<blockquote> I learned a couple of new tricks and new uses for the old ones. </blockquote> That was exactly my purpose. :-)

pherapont on June 8, 2019, 6:20 a.m.
Thank You for your solutions. They help to understand Python much deeper.

r.bathoorn on April 14, 2021, 1:20 p.m.
i like it, but if i see it again in 6 months i will have to spend some time to understand it again

veky on April 14, 2021, 1:21 p.m.
Then rewrite it, as many people have already done (to their great benefit). ;-)

mithilkotak on Sept. 19, 2022, 5:44 a.m.
Genius. Short, sweet and creative. If someone is trying to code golf then they can use this solution by removing some spaces. I wrote a solution for general size of Tic-Tac-Toe grid. It would be great to see your solution adapted for that purpose.

veky on Sept. 19, 2022, 9:29 a.m.
This solution is not really generalizable, among other reasons because it would require multidigit (and dynamic) numbers. But I have other solutions. 😉

rockwellshabani on Oct. 26, 2023, 12:54 p.m.
I always learn something new trying to understand your solutions. I like how you tend to use functional programming concepts, which one doesn't often see here.

veky on Oct. 26, 2023, 6:39 p.m.
First sentence: great, and exactly the reason why I'm writing them this way. Second sentence: I'm trying to use features of Python which aren't often seen here, yes (if they can be used effectively for solving the mission), but here I really wouldn't put such an emphasis on functional programming. next and slicing are the true heroes here, and neither of them is particularly "functional" in that sense: next has implicit state, and slicing is value-semantical.

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