#A loop is possible whenever there are two of the same lettter an even distance 
#greater than 2 from each other
def first_loop(letters)
  0.upto(letters.length-1) do |idx1|
    (idx1+4).step(letters.length-1,2) do |idx2|
      return [idx1,idx2] if letters[idx1].casecmp(letters[idx2])==0
    end
  end
  nil
end

letters = ARGV.first.split(//)

first,last = first_loop(letters)

if first==nil
  puts "No loop"
  exit
end

letters[(last+1)..-1].reverse_each {|l| puts ' '*first + l}
puts letters[0..(first+1)].join
1.upto((last-first-1)/2) do |n|
  puts ' '*first + letters[last-n] + letters[first+1+n]
end

----- Original Message ----
From: Ruby Quiz <james / grayproductions.net>
To: ruby-talk ML <ruby-talk / ruby-lang.org>
Sent: Friday, December 7, 2007 2:45:02 PM
Subject: [QUIZ] Word Loop (#149)


The three rules of Ruby Quiz:

1.  Please do not post any solutions or spoiler discussion for this
 quiz until
48 hours have passed from the time on this message.

2.  Support Ruby Quiz by submitting ideas as often as you can:

http://www.rubyquiz.com/

3.  Enjoy!

Suggestion:  A [QUIZ] in the subject of emails about the problem helps
 everyone
on Ruby Talk follow the discussion.  Please reply to the original quiz
 message,
if you can.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

Here's a fun little challenge from the Educational Computing
 Organization of
Ontario.

Given a single word as input try to find a repeated letter inside of it
 such
that you can loop the text around and reuse that letter.  For example:

    $ ruby word_loop.rb Mississippi
     i
     p
     p
    Mis
     ss
     si

or:

    $ ruby word_loop.rb Markham
    Ma
    ar
    hk

or:

    $ ruby word_loop.rb yummy
    yu
    mm

If a loop cannot be made, your code can just print an error message:

    $ ruby word_loop.rb Dana
    No loop.






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