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Date: Sat, 06 Jun 2009 09:22:32 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: find words that contains some specific letters
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Date: 2009-06-06T09:22:32-07:00
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John B. Matthews wrote:
> In article <78rpbkF1mqrc7U1@mid.individual.net>,
>  "Giovanni Azua" <bravegag@hotmail.com> wrote:
> 
>> "Patricia Shanahan" <pats@acm.org> wrote in message
>>> A perfect hash function is one that guarantees distinct hash codes 
>>> for a specific set of keys. There are algorithms for constructing 
>>> one, given a set of keys.
>> For example the Character class.
> 
> I think all of the primitive wrappers (except Double) have trivially 
> perfect integer hashes, as they wrap distinct values. Patricia was 
> perhaps referring to algorithms of the kind discussed here:
> 
> <http://en.wikipedia.org/wiki/Perfect_hash_function>

Yes, that's the sort of thing I meant.

The Long hash code is also not perfect, and cannot be, because there are
more longs than ints.

Patricia