On Wed, Sep 29, 2010 at 1:15 AM, rog <r...@pynguins.com> wrote: > Shashwat Anand wrote: > > >> >> On Wed, Sep 29, 2010 at 12:14 AM, Rog <r...@pynguins.com <mailto: >> r...@pynguins.com>> wrote: >> >> Hi all, >> Have been grappling with a list problem for hours... >> a = [2, 3, 4, 5,.....] >> b = [4, 8, 2, 6,.....] >> Basicly I am trying to place a[0], b[0] in a seperate list >> IF a[2] and b[2] is present. >> >> >> You are not exactly clear with your problem statement. >> Care to elaborate it more. >> >> I have tried sets, zip etc with no success. >> I am tackling Euler projects with Python 3.1, with minimal >> knowledge, and having to tackle the language as I progress. >> Enjoyable frustration :) >> >> -- >> Rog >> http://www.rog.pynguins.com >> -- >> http://mail.python.org/mailman/listinfo/python-list >> >> >> >> >> -- >> ~l0nwlf >> > > "Let d(/n/) be defined as the sum of proper divisors of /n/ (numbers less > than /n/ which divide evenly into /n/). > If d(/a/) = /b/ and d(/b/) = /a/, where /a/ ≠ /b/, then /a/ and /b/ are an > amicable pair and each of /a/ and /b/ are called amicable numbers. > > For example, the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, > 55 and 110; therefore d(220) = 284. The proper divisors of 284 are 1, 2, 4, > 71 and 142; so d(284) = 220. > > Evaluate the sum of all the amicable numbers under 10000." > > from Project Euler. > I have all answers contained in two lists but need to extract the amicable > pairs. > eg > a = [200, 4, 284,.....] > b = [284, 9, 200, ......] > Hope that helps. > Thanks for the link. >
I am not sure how and what you managed, but what I understand you need to calculate sum of divisors. A quick unoptimized solution can be, >>> def divsum(n):return sum(i for i in range(1, n) if not n % i)... >>> >>> divsum(220)284>>> divsum(284)220 Now all is left is looping and little maths, since upper bound is not high, brute force is Ok. <spoiler> http://codepad.org/g6PRyoiV </spoiler> # For reference Also I guess you missed 'Reply All', please take care of it next time. > Rog > > -- ~l0nwlf
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