Simple resolution in Crystal for the Google Code Jam discussed here: http://blog.clifreeder.com/blog/2013/04/21/ruby-is-too-slow-for-programming-competitions/

palindromes.cr

class Int64
  def palindrome?
    num = self
    reverse = 0_i64
    while num > 0
      dig = num % 10
      reverse = reverse * 10 + dig
      num = num / 10
    end
    self == reverse
  end
end

i = 0
File.open(ARGV[0], "r") do |file|
  file.gets
  while line = file.gets
    start, finish = line.split(" ").map { |part| part.to_i64 }
    sqrt_start = Math.sqrt(start).to_i64
    sqrt_finish = Math.sqrt(finish).to_i64
    j = sqrt_start
    found = 0
    while j <= sqrt_finish
      if j.palindrome?
        square = j * j
        if square >= start && square <= finish && square.palindrome?
          found += 1
        end
      end
      j += 1
    end
    puts "Case ##{i + 1}: #{found}"
    i += 1
  end
end