On Feb 7, 2:29 am, [EMAIL PROTECTED] wrote: > On Feb 1, 8:25 pm, "Krypto" <[EMAIL PROTECTED]> wrote: > > > The correct answer as told to me by a person is > > (N>>3) + ((N-7*(N>>3))>>3) > > The above term always gives division by 7 > > Does anybody else notice that this breaks the spirit of the problem > (regardless of it's accuracy)? 'N-7' uses the subtraction operator, > and is thus an invalid solution for the original question. > > Build a recursive function, which uses two arbitrary numbers, say 1 > and 100.
Recursive? Bzzzt! > Check each, times 7, and make sure that your target number, > N, is between them. Increase or decrease your arbitrary numbers as > appropriate. Now pick a random number between those two numbers, and > check it. Figure out which two the answer is between, and then check a > random number in that subset Might it not be better to halve the interval at each iteration instead of calling a random number function? mid = (lo + hi) >> 1 looks permitted and cheap to me. Also you don't run the risk of it taking a very high number of iterations to get a result. >. Continue this, and you will drill down > to the correct answer, by using only *, +, >, and <. > > I'll bet money that since this was a programming interview, that it > wasn't a check of your knowledge of obscure formulas, but rather a > check of your lateral thinking and knowledge of programming. > > ~G Did you notice the important word *efficiently* in line 1 of the spec? Even after ripping out recursion and random numbers, your proposed solution is still way off the pace. Cheers, John -- http://mail.python.org/mailman/listinfo/python-list
