in reply to Re^2: Golf: Buying with exact change
in thread Golf: Buying with exact change

I'm justpointing out that the regex solution is terrible once the numbers start to get large. Efficiency is not the primary concern in golf but a soution should terminate before the sun dies :-)

Another problem I have with the regex solution is that you don't know how much is enough for any given input. I'd say twice the largest 2 number would do it but I'm not sure, there will be complications when some of the numbers share factors.

It's an interesting puzzle though, it has a very simple solution when there's only 2 numbers:
largest(m, n) = (m - 1) * (n - 1) - 1

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Re^4: Golf: Buying with exact change
by Anonymous Monk on Feb 22, 2005 at 09:12 UTC
    Well, only if there is a solution. For instance, if you plug in 4 and 2 in your solution, you'll get 2 as an answer - but it's obvious you can pay 2 exactly. Note that for 2 numbers there is a (finite) answer if and only if the 2 numbers are relative prime. (Which is easy to see, if they aren't relative prime, they share a prime number p in their factors. Which means that any amount you can pay will be a multiple of p.)
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