plug board

plugboard.rb

class Plugboard
  def initialize(wires = "")
    chars = wires.split('')
    if chars.length % 2 == 1 || chars.length > 20
      raise
    end
    
    @hash = Hash.new
    chars.each_with_index do |c, index|
      if index % 2 == 0
        character_ahead = chars[index+1]
        if @hash[c] || @hash[character_ahead]
          raise
        end
        
        @hash[c] = character_ahead
        @hash[character_ahead] = c        
      end
    end
   end
  def process(wire)
    answer = @hash[wire]
    return answer ? answer : wire

plugboard2.rb

class Plugboard

  def initialize(wires = "")
    if wires.length % 2 > 0
      raise 'un-assigned character'
    end
    wires.split(//).each do |c|
      if c<'A' || c>'Z'
        raise 'character out of bound'
      end
    end
    if wires.split(//).length > wires.split(//).uniq.length
      raise 'duplicate association'
    end
    if wires.length > 20
      raise 'cannot be more than 10 pairs'
    end
    
    x = wires.split(//)
    @codes = Hash.new
    (0...(x.length)).step(2) do |i|
      @codes[x[i]] = x[i+1]
      @codes[x[i+1]] = x[i]
    end
    
  end
  
  def process(wire)
    if !@codes[wire].nil?
      @codes[wire]
    else
      wire
    end
  end
end