From: Martin DeMello <martindemello@...>
Date: 2007-01-11T22:54:13+09:00
Subject: Re: [SUMMARY] Word Blender (#108)

On 1/11/07, Ruby Quiz <james@grayproductions.net> wrote:
>
> The main trick used in this recursive grouping of words is the use of
> "signatures."  A word's signature is just the sorted order of the letters in the
> word:  aejms for james, for example.  Comparing signatures makes it trivial to
> find words that use the same letters, since their signatures will be the same.
>
> Using the signatures, the choices() method just removes one character at a time
> recursing through the word list.  This allows me to find all of the smaller
> words that can be formed using the same letters.

I used a different signature method - I mapped each unique letter in
the target word to a prime, and then used the product of the primes of
all the letters in a word as its signature. That way, a is contained
in b if signature(b) % signature(a) == 0, and you can generate the
signatures via each_byte, array lookup and integer multiplication (no
need for split, sort or string deletion).

martin