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One for me as a noob hard task

Joakim Olsson

11/19/2007 7:10:00 PM

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
without using the sort method. It says I shall do it at
http://pine.fm/LearnToProgram/?... but I'm stuck.

If I use the sort method, I do it like this:

words = []
while (word = gets.chomp) != ""
words << word
end
puts
puts words.sort
--
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6 Answers

Sebastian Hungerecker

11/19/2007 7:23:00 PM

0

Joakim Olsson wrote:
> and which then repeats the words back to us in alphabetical order
> without using the sort method. It says I shall do it at
> http://pine.fm/LearnToProgram/?... but I'm stuck.

http://en.wikipedia.org/wiki/Sorting_algorithm#Summaries_of_popular_sorting_...
Pick one (bubble sort is quite easy) and then implement it in ruby.


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ICQ: 205544826

Jano Svitok

11/19/2007 7:35:00 PM

0

On Nov 19, 2007 8:22 PM, Sebastian Hungerecker <sepp2k@googlemail.com> wrote:
> Joakim Olsson wrote:
> > and which then repeats the words back to us in alphabetical order
> > without using the sort method. It says I shall do it at
> > http://pine.fm/LearnToProgram/?... but I'm stuck.
>
> http://en.wikipedia.org/wiki/Sorting_algorithm#Summaries_of_popular_sorting_...
> Pick one (bubble sort is quite easy) and then implement it in ruby.

Or for the beginning, before you try to implement any of those
algorithms, you may try this:
Just image how YOU would sort a pile of cards with those words on
them. What would you do?

Then try to implement it in ruby. The pile is your array. You may (or
not) need another pile, and some basic operations:
remove a card from the stack, and insert it in some other place, and
maybe more. You don't have to make it fast,
or efficient. Just try to make it work anyhow.

If you're stuck, try with small arrays - the smallest one is empty ;-)
It's easy to sort an empty array, right? Then try one word.
Still easy. Two words? Three? Four?

After you have done this, look at the "properly designed" algorithms
and try to implement some of them.

Finally you can more-or-less forget about this all and use the sort
method ;-) It's always good to know what's
going on under the hood.

Good luck!

Jano

Joakim Olsson

11/19/2007 7:49:00 PM

0

>
> Good luck!
>
> Jano

Thanks for the cool answer! However, I must say that I can't solve the
problem yet. I guess I should use the pop method and the <-thingy but I
can't solve it.
--
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Joakim Olsson

11/19/2007 8:18:00 PM

0

Now a person wrote this to me:

sorted=[]; words.length.times do sorted<<words.delete(words.min) end;
sorted

How can I use that in the code? It would be really nice with an example
which I can read and then understand.
--
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Sebastian Hungerecker

11/19/2007 8:28:00 PM

0

Joakim Olsson wrote:
> Now a person wrote this to me:

That person was me.


> sorted=[]; words.length.times do sorted<<words.delete(words.min) end;
> sorted
>
> How can I use that in the code?

It returns the sorted array. You can puts it or do whatever you want with it.

> It would be really nice with an example
> which I can read and then understand.

words=gets("").split("\n")
sorted=[];
# At this point sorted is an emtpy array and words is an unsorted array
# of the words that the user entered.

words.length.times do # Do the following as many times
# as there are items in words.
sorted << words.delete(words.min)
# Take the smallest item in words (words.min),
# delete it from words (words.delete) and then
# put it at the end of sorted (sorted <<)
end

puts sorted # Print the sorted array to the screen


HTH,
Sebastian
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Joakim Olsson

11/19/2007 9:04:00 PM

0

words = []
sorted=[]
while (word = gets.chomp) != ""
words << word
end
words.length.times do
sorted << words.delete(words.min)
end
puts
puts sorted

That worked it out! Thank you, Sebastian and everybody else!
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