RPCFN: Ruby**Fun (#4) submisson

README.rdoc

RPCFN: Ruby**Fun (#4)¶ ↑

This is my submission for the RPCFN: Ruby**Fun (#4)

rubylearning.com/blog/2009/11/26/rpcfn-rubyfun-4/

Explanation ¶ ↑

The algorithm implemented is trying to be as simple yet readable as possible

• Iterates every coefficient in the input array. If the coefficient is non zero, performs a number of actions on it.

Usage¶ ↑

>> require 'Polynomial'
>> puts Polynomial.new([-2,-3,-4,-5])
   -2x^3-3x^2-4x-5

pedrodiogo.rb

class Polynomial
  def initialize(input)
    raise ArgumentError, "Need at least 2 coefficients" if input.size < 2

    @input, @output = input, String.new
    process
  end

  def to_s
    @output
  end
  
  def process
    @input.each_index do |n|
      unless @input[n] == 0
        degree = @input.size - n - 1 # degree of the coefficient
        
        @output << '+'                  if @input[n] > 0 && !@output.empty? # Prevents adding '+' in the begginning
        @output << '-'                  if @input[n] < 0
        @output << @input[n].abs.to_s   if @input[n].abs != 1 || degree == 0 # Prevents adding '1' unless the degree is 0
        @output << 'x'                  if degree > 0
        @output << '^' + degree.to_s    if degree > 1
      end
    end
    
    # If the output string is still empty, it means the polynomial is 0
    @output = "0" if @output.empty?
  end
end