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By: a guest on Jun 17th, 2012  |  syntax: None  |  size: 0.47 KB  |  hits: 15  |  expires: Never
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  1. #!/usr/bin/env ruby
  2. require 'prime'
  3. require 'mathn'
  4.  
  5. def shifts(arr)
  6.   res = []
  7.   tmp = arr.dup
  8.   (0..arr.length-1).each do |a|
  9.     tmp << tmp.shift
  10.     res << tmp.dup
  11.   end
  12.   res
  13. end
  14.  
  15. no_zeros = Prime.each(1000000).select do |num|
  16.                                   ! num.to_s.split("").include?("0")
  17.                                 end
  18. res = no_zeros.select do |num|
  19.         shifts(num.to_s.split("")).all? do |n|
  20.           n.join.to_i.prime?
  21.         end
  22.       end
  23.  
  24. p res.size