@abhishek : Can you show me the code ? 10**12 is way too much. My code gives output within a minute for 10**8 and fails. Ofcourse I need to apply some algo here. What do you exactly mean by taking out rightmost 7 digits ?
On Mon, Sep 14, 2009 at 8:14 PM, Abhishek Mishra <ideam...@gmail.com> wrote: > I remember doing something very inaccurate a long time ago for this - > 1. find everything in a loop > 2. everytime you encounter some zeros, strip them > 3. everytime after stripping it exceeds say 7 digits, take out > rightmost 7 digits for accuracy's sake > 4. proceed till loop ends > 5. print out the rightmost 5 digits of what remains > > Highly inaccurate but helped crossing icpc prelims in 1st year because > there were humans who checked my solution with smaller inputs :) > > On Mon, Sep 14, 2009 at 6:36 PM, Shashwat Anand > <anand.shash...@gmail.com> wrote: > > > > How do we calculate last 5-digits of 10**12 ignoring trailing zeros. The > code i wrote works good until 10**8 and after that take ages. > > The source of problem is Project Euler : > http://projecteuler.net/index.php?section=problems&id=160 > > > > The code is pasted here : http://paste.pocoo.org/show/139745/ > > > > 1 ''' > > 2 For any N, let f(N) be the last five digits before the trailing > zeroes in N!. > > 3 For example, > > 4 > > 5 9! = 362880 so f(9)=36288 > > 6 10! = 3628800 so f(10)=36288 > > 7 20! = 2432902008176640000 so f(20)=17664 > > 8 > > 9 Find f(1,000,000,000,000) > > 10 ''' > > 11 def f(n): > > 12 fac = 1 > > 13 i = 1 > > 14 #for i in range(1, n+1): > > 15 while i < n + 1: > > 16 fac = int(str(fac * i).strip('0')) % 100000 > > 17 i += 1 > > 18 return fac > > 19 > > 20 print f(1000000000000) > > > > PS. hope posting algorithmic doubts will not be considered spamming :) > > > > > > _______________________________________________ > > BangPypers mailing list > > BangPypers@python.org > > http://mail.python.org/mailman/listinfo/bangpypers > > > _______________________________________________ > BangPypers mailing list > BangPypers@python.org > http://mail.python.org/mailman/listinfo/bangpypers >
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