On 15 June 2010 22:55, superpollo <ute...@esempio.net> wrote: > Peter Otten ha scritto: > > superpollo wrote: >> >> goal (from e.c.m.): evaluate >>> 1^2+2^2+3^2-4^2-5^2+6^2+7^2+8^2-9^2-10^2+...-2010^2, where each three >>> consecutive + must be followed by two - (^ meaning ** in this context) >>> >> >> from itertools import cycle, izip >>>>> sum(sign*i*i for sign, i in izip(cycle([1]*3+[-1]*2), range(1, 2011))) >>>>> >>>> 536926141 >> > > don't understand it bit i like this a lot!
Peter's solution is really identical as mine, except he used a generator and I used a modulo operator. Cheers, Xav
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