On 11/10/2010 4:36 AM Felipe Vinturini said...
Hi Folks,
I am quite new to python and I don't have a lot of experience with it yet.
I have two simple questions:
1. Is there a way to limit the number of times a list comprehension will
execute? E.g. I want to read from input only 5 values, so I would like
something like (the values between # # are what I want):
===================================================================================
COUNT = 0
print [ v for v in sys.stdin.readlines() *# *IF COUNT< 5* #* ] ## Increment
COUNT somewhere
Easiest would be print [ v for v in sys.stdin.readlines()[:5] ] but that
still reads the entire sys.stdin (whatever it may be...)
===================================================================================
2.* *I would like to know another way, a more pythonic way, to write the
following:
===================================================================================
import sys
def Z(iNumber):
sum=0
while (iNumber>=5):
iNumber=iNumber/5
sum = sum + iNumber
print sum
def factorialCountZeros2():
sysStdinReadLine = sys.stdin.readline
numValues = int(sysStdinReadLine())
[ Z(int(sysStdinReadLine())) for x in xrange(numValues) ]
if __name__ == '__main__':
factorialCountZeros2()
===================================================================================
To be more specific, I would like to know about the Z function, is there a
way to rewrite that while with list comprehension?
Well, you could use
def X(iNumber):
print sum([iNumber/(5**ii) for ii in range(1,2*int(len("%s" %
iNumber)))])
but the range selection is rather arbitrary.
Emile
This code is to solve the CodeChef problem:
http://www.codechef.com/problems/FCTRL/ (I am still in the easy part) and it
executed in 2.5 secs, I would like to know if there is something else I can
improve performance.
Thanks for your attention!
Regards,
Felipe.
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