isleyaardvark.rb

# This class prepares a pretty-print version of a polynomial with a minimum of 2 coefficients
#
class Polynomial
  
  # Create the polynomial object and store the coefficients
  #
  def initialize(args)
    raise ArgumentError, "Need at least 2 coefficients" if args.length < 2
    @args = args
  end

  # Returns a string version of the polynomial, simplifies coefficients of 1x^n to x^n,
  # simplifies x^1 to x and ax^0 to a. Doesn't include elements with a coefficient of 0.
  # If all coefficients = 0, returns "0".
  #
  def to_s
    polynomial = []
    @args.each_with_index do |coefficient, index| 
      unless coefficient.zero?
        polynomial << coefficient.to_s + "x^" + (@args.length - 1 - index).to_s
      end
    end
    
    unless polynomial.empty?
      return polynomial.join("+").gsub(/\+\-/, '-').gsub(/(^|[\+\-])[1]x/, '\1x').gsub("x^1", 'x').gsub("x^0", '')
      # ^| in regex handles case where 1x is at beginning of line, otherwise it's -1x and is covered by rest of regex
    else
      return "0"
    end
  end

end