From: Wyatt Greene <greenewm@...>
Date: 2008-05-04T22:05:02+09:00
Subject: Re: Array combination check

On May 4, 8:50 am, Nadim Kobeissi <kaep...@mac.com> wrote:
> Xavier Noria wrote:
> > What is a combination?
>
> Please allow me to make myself more clear:
> bunny=["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
> cow="hello"
>
> I want to test all possible combinations of the items inside bunny (the
> alphabet) starting from the smallest to the biggest (a, then b, then c..
> then aa, then ab, then ac, etc.) until I arrive to a case in which the
> combination == cow, which means the combination would be "hello".
> --
> Posted viahttp://www.ruby-forum.com/.

You could try a brute-force algorithm, which uses loops to do exactly
what you said:  try "a" then "b" then "c", then try "aa", "ab",
"ac"..., then "ba", "bb", etc.  String has a succ method which would
be useful for this.

The problem is that the brute-force algorithm will be slow.  For the
example given, I think it will take around 26^5 (about 11 million)
iterations before it matches on a string of size 5.  If you want a
faster algorithm, I would work backwards from the starting string
"hello".

Wyatt