single_linked_list.rb

class Element 
    attr_accessor :value, :next_value

    def initialize(value, next_value)
        @value = value
        @next_value = next_value
    end
end

class SingleLinkedList
  def initialize(value)
    @head = Element.new(value, nil)
  end
   
  def add(value)
    current = @head
    while current.next_value != nil
      current = current.next_value
    end
    current.next_value = Element.new(value, nil)
  end
   
  def delete(value)
    current.next_value = @head
    if current.value = value
      @head = current.next_value
    else
      while (current.next_value != nil) && (current.next_value.value != value)
        current = current.next_value
      end
      unless current.next_value == nil
        current.next_value = current.next_value.next_value
      end
    end
  end
   
  def return_list
    elements = []
    current = @head
    while current.next_value != nil
      elements << current
      current = current.next_value
    end
    elements << current
  end 

  def length 
    count = 0
    current = @head
    if current != nil
      while current.next_value != nil 
        count+=1
        current = current.next_value;
      end
    else 
      return 0    
    end
    count
  end
end

list = SingleLinkedList.new(1)
list.add(2)
list.add(3)
list.add(4)
list.add(5)
list.add(100)
p list.return_list
p list.length
p list.length