First clear solution for Restricted Sum by ciel - python coding challenges

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First solution in Clear category for Restricted Sum by ciel

def checkio(data):
    if len(data)==0: return 0
    return data[0]+checkio(data[1:])

Feb. 15, 2014

Comments:

ArchTauruS on Aug. 11, 2014, 2:56 a.m.
great!

CounterSparta on Aug. 16, 2014, 9:15 a.m.
Nice one

crazyzubr on Sept. 6, 2014, 6:10 a.m.
<pre class='brush: python'>if len(data)==0: return 0 </pre> redundant, so better <pre class='brush: python'>if not data: return 0 </pre>

AlexeyNesterenko on Dec. 17, 2014, 3:45 p.m.
<blockquote> if not data: return 0 redundant if bool(data): return data[0]+checkio(data[1:]) return 0 </blockquote>

ZoltanOnody on Jan. 15, 2015, 10:07 p.m.
Isn't it O(n^2) ?

LLCheckio on Jan. 18, 2015, 3:01 p.m.
It's O(n). We recursively call the function checkio(data) one time by one element the list.

ZoltanOnody on Jan. 18, 2015, 4:36 p.m.
Yeah I got it but I thought that l[1:] operation is also O(N), I need to conduct a research about these operations in python :-)

ciel on Jan. 18, 2015, 6:05 p.m.
It should be O(1), if copy-on-write is implemented properly...

LLCheckio on Jan. 18, 2015, 2:55 p.m.
If you will do it like below, so it will be less by one iteration: <pre class='brush: python'>if len(data) == 1: return data[0] </pre>

ciel on Jan. 18, 2015, 6:04 p.m.
Well, yes, it is up to us whether to accept <pre class='brush: python'>checkio([]) </pre>

gethappy on Feb. 25, 2015, 1:15 p.m.
It's good, but you make new list in every iteration. It's not good to do recursion with additional memory, because it eats memory from stack.

ciel on March 1, 2015, 2:43 p.m.
Umm, it turned out that Python doesn't have copy-on-write stuff; I should have used data.pop(). Republished to <a href="http://www.checkio.org/mission/restricted-sum/publications/ciel/python-3/third/">http://www.checkio.org/mission/restricted-sum/publications/ciel/python-3/third/</a>

mauricioabreu on April 19, 2015, 9:24 p.m.
Gooood! It looks like erlang/elixir. You use the head to perform the sum and pass the "tail" to the function in a recursive way.

giolefpaceid on May 24, 2015, 2:50 p.m.
Similar one here!

Dracunos on Dec. 28, 2015, 4:01 p.m.
Mine was similar except I used try/except, I read somewhere that was better, but none of the top solutions I saw seemed to use that method. Are there any benefits/downsides using try/except vs conditional? Like differences in speed or code flexibility?

ljy95135 on May 27, 2016, 10:48 a.m.
I also solve it by recursive function, good idea!

Thenbacker on Oct. 10, 2016, 7:28 p.m.
Nice use of recursion!

julieno on Jan. 9, 2017, 4:13 a.m.
Super! Short and clear!

Adam_Navarrete on Feb. 3, 2017, 1:40 a.m.
Bien.

J.W on March 29, 2018, 9:53 p.m.
same as mine. :D

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