WCC W03::C01 Curious Number

curious_numbers.rb

def curious_numbers
  curious_number_list = []
  (1..9999999999).each_slice(100000).each do |numbers|
    numbers.each do |number|
      square = number ** 2
      number_of_digit = number.to_s.length
      if(square.to_s[-number_of_digit..-1].to_i == number)
        curious_number_list << number
      end
    end
  end
  curious_number_list
end

curious_numbers

### Another way
def curious_numbers(number_of_digit)
  curious_number_list = []
  1.upto(number_of_digit).each do |digit|
    first_curious_number = 5**(2**digit) % 10**digit
    second_curious_number = 10**digit - first_curious_number + 1
    curious_number_list << first_curious_number 
    curious_number_list << second_curious_number
  end
  curious_number_list.sort.uniq
end

curious_numbers(10)