From: Todd Benson <caduceass@...>
Date: 2008-11-28T08:22:35+09:00
Subject: Re: Programming Noob Chris Pine Tutorial sorting without use of array.sort method

On Thu, Nov 27, 2008 at 3:30 PM, whisperjim <jgheal@googlemail.com> wrote:
> I'm working through the following tutorial http://pine.fm/LearnToProgram/
> (recommended by the official Ruby site)
> as a starting point and I've got to chapter 7 and struggling with  the
> following  assignment........
>
> " 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? "
>
> Now I'm supposed to do this without any .sort method and the chapters
> I've covered so far (1 ~ 7) have not covered method creation,
> Classes,Blocks or Procs, so the challenge is to solve the assignment
> without using them.
>
> Now I've written a program but I think the basic 'mental model' is
> flawed, I say this because of the results I'm getting.
>
> If I use the following input [ q w e r t y ] I end up with [ e q r t w
> w ] and the input [ z x c v b ] end up as [ b b b b b ].
>
> If my mental model is o.k, then my code must be wrong, but I'm stumped
> at to where.
>
> # concept - store words in 1st array (words_array). Find the
> 'smallest' word alphabetically by selecting the last word (call it
> wordCheck) and compare 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 first unsorted
> 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.
>
>
> 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
>
> Guidance greatly appreciated.

Cheating...

a = my_word_array
sorted = []
while !a.empty?; sorted << a.delete(a.min); end

Todd