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From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject: Re: Balanced trees
Date: Mon, 10 Mar 2014 19:57:00 -0400
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Xref: csiph.com comp.lang.python:68183

On 10 Mar 2014 03:24:08 GMT, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> declaimed the following:

>
>Proof: I create a hash table that accepts unsigned bytes as keys, where 
>the hash is the value of the byte. So byte 0x42 hashes to 0x42, or 
>decimal 66. I give the hash table 256 slots, numbered from 0 to 255. 
>Every hash takes constant time, there are no collisions at all, lookups, 
>insertions and deletions all take constant time regardless of how full 
>the table is. The best, worst and average cases are not just O(1) but 
>also ?(1).
>
	What you've defined, however, can be replaced with straight list
indexing <G> No hash function needed.

	If there is a finite (and small) number of possible keys, the list will
likely beat the hash.

	OTOH, when the keys exceed reasonable list storage, the hash becomes
useful -- but one now has to be concerned with collisions.

	Back in the day, I was somewhat pleased to discover that the Amiga
directory structure was a real world example of something I'd only seen as
a class assignment in my data structures class: a hashed-head
multiple-linked list.
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/