From: Michael Morin <uzimonkey@...>
Date: 2008-08-31T07:46:25+09:00
Subject: Re: Another Chris Pine Tutorial Question

danielj wrote:
>  Let's write a program which asks us to type in as many words as we
> want (one word per line, continuing until we just press Enter on an
> empty line), and which then repeats the words back to us in
> alphabetical order. OK?
> 
> So... first we'll�uh... um... hmmm... Well, we could�er... um...
> 
> You know, I don't think we can do it. We need a way to store an
> unknown amount of words, and how to keep track of them all together,
> so they don't get mixed up with other variables. We need to put them
> in some sort of a list. We need arrays.
> puts "Let's make a shopping list!"
> 
> shoplist = []
> 
> while shoplist.last != ''
> 
> shoplist.push(gets.downcase.chomp)
> 
> end
> 
> shoplist.pop
> 
> 
> puts shoplist.sort
> 
> The program asks for one word per line but there is no way one can do
> that utilizing the methods the tutorial has expounded upon up to this
> point so I settled for what I got here.
> 
> However, it asks you to then do this:
> 
> � Try writing the above program without using the sort method. A large
> part of programming is solving problems, so get all the practice you
> can!
> 
> Could somebody point me in the right direction, or give me an example
> of how that would be possible? I'm racking my brain but I can not
> think of a way to do it without using methods and tools that you are
> not yet supposed to use at this point in the tutorial (i.e. regex)
> 

There's not really any point to limiting yourself.  Whatever you come up 
with will essentially be a crude or simplified sorting algorithm.  If 
you really didn't want to use the sort method, you could do something 
like this:

words = []
while true
   word = gets.chomp
   break if word == ''
   words << word
end

while words.size > 0
   word = words.min{|a,b| a.downcase <=> b.downcase }
   puts word
   words -= [word]
end

However, what you've ended up doing is creating something a lot like a 
selection sort only instead of swapping with the front of the list 
you're printing it and removing it from the list.  In effect, it's just 
a really inefficient version of sort.

Maybe you've taken this as a personal challenge, but I've come to except 
some (most?) texts have at least some little quirks like this.  They're 
best ignored while you move on to more interesting things.  If you want 
a challenge, there's a huge backlog of RubyQuiz problems that are much 
more interesting.

-- 
Michael Morin
Guide to Ruby
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