From: Stefan Mahlitz <stefan@...>
Date: 2005-07-20T02:20:55+09:00
Subject: Re: [SOLUTION] Sampling (#39)

Olaf Klischat wrote:
> Stefan Mahlitz <stefan@mahlitz-net.de> writes:
> 
>>Why use a Hash?
> 
> Efficiency. Array#include? runs in linear time (i.e. the running time
> is proportional to the size of the array because all elements have to
> be tested sequentially), while Hash#[] runs in constant time (i.e. the
> running time is independent of the size of the hash). So the
> array-based solution will scale very badly for large numbers.

I knew that after the benchmarks. ;)

To ask the same question in another way: How would someone not being
aware of the advantages a Hash-lookup gives (compared to Array-lookup)
choose to implement the problem with a Hash? It is not obvious for
inexperienced programmers.

Well, I remembered after seeing the first solution with Hash (it has
been a long time since I wrote the last program).

Stefan Mahlitz