From: Hugh Sasse <hgs@...>
Date: 2008-11-26T07:38:41+09:00
Subject: Re: Chris Pine tutorial assistance chapter 7 sort data without use of  .sort method

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On Wed, 26 Nov 2008, jgheal@googlemail.com wrote:

> On Nov 25, 2:37�pm, Hugh Sasse <h...@dmu.ac.uk> wrote:
> > [lots of stuff worth trimming]
> 
> # basic mental model - store words in 1st array (words_array). Find
> the 'smallest' word alphabetically by selecting the last word (call it
> wordCheck) from words_array and compare wordCheck with the first word,
> second word and so on..... and exchange the value of wordCheck with
> the other word (1st/2nd... word) if the other word value happens to be
> less. Start the checking again with the first word, second word....
> and so on until a counter has been reached (counter equal to 'current'
> length of words_array). Once the counter has been reached, put the
> value of wordCheck into a second array (sortedWords_array) and delete
> wordCheck value from first unsorted array (words_array) and repeat
> until words_array is empty.

I think this should work.  You will learn more efficient ways to do this,
but this is a good start.  Knuth recommends thinking about how to solve
sorting problems yourself first, before consulting other algorithms. 


> 
> puts 'Type in as many words as you want and once you\'ve had enough,
> just \'enter\' a clear line.'
> 
> words_array = []      # create 1st array called words_array to store users
> unsorted values
> 
> loop do
>    input = gets.downcase.chomp        # take the user input, remove the
> 'enter' off the tail and lower the case and call ...
>    break if input.empty?      # .. it 'input' , break from the loop if
> 'input' is equal to empty
>    words_array << input               # push 'input' to the words_array
> 
> end
> 
> wordCheck = words_array.last  # wordCheck is equal to the last 'input'
> stored in the words_array
> rotateCounter = 0
> sortedWords_array = []                # create 2nd array to contain 'sorted' values
> 
> until words_array.length == 0 # exit once no words left in the first
> unsorted array
> 
>       while rotateCounter <= words_array.length # exit if rotate counter
> greater than words contained within first array

>               if words_array[0] >= wordCheck # continue if first word in 1st array
> greater or equal to wordCheck value
> 
>                       words_array.push words_array.shift # rotate the first unsorted
> array
>                       rotateCounter = rotateCounter + 1 # add 1 to counter
> 
>               else wordCheck = words_array[0] # replace current value (wordCheck)
> with 'smaller' word
>                       rotateCounter = 0       # reset counter to zero
>               end
> 
>       end
> 
>       sortedWords_array.push wordCheck        # add wordCheck value to 2nd array
> 
>       until wordCheck = words_array.last      # rotate first array until a
> matching ..
>               words_array.push words_array.shift # .. value found at the back of
> the first array
>       end
>       words_array.pop                         # remove the last value contained within the 1st
> array
>       rotateCounter = 0                       # reset rotate counter
>       wordCheck = words_array.last            # replace current value of wordCheck
> with new last word from 1st array
> end
> puts sortedWords_array        # print values within 2nd array, which should
> be in low to high alphabetical order
> 
> # Hope the above is legible
> 
> 

So, what output do you get that is wrong?  This code works for me, for 
the input "words" 
a
b
a
c
a
b

        Hugh
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