From: Peter Fitzgibbons <Peter.Fitzgibbons@...>
Date: 2005-04-28T23:30:49+09:00
Subject: Re: TIMTOWTDI letter permutation

> Endy Tjahjono <endy_c@deadspam.com> wrote:
> ...
> 
> Notice how the first 6 start with 'a', the next 6 with 'b', etc.
Within each block of 6, you have 2 permutations starting with each of
the remaining letters. You can generalise this pattern to directly
calculate the ith permutation of n letters, given n and i. Your
generator then becomes
> 
> 1..upto(n.factorial) {|i| puts permutation(n, i)}
> 
> with no recursion at all.
> 
> martin

What's the practical applicatin of being able to pick-off the i.th
permutation of an array?

Peter J. Fitzgibbons
Applications Manager
Lakewood Homes - "The American Dream Builder"(r)
Peter.Fitzgibbons@Lakewoodhomes.net
(847) 884-8800