chase stack demo

linked_list_node.rb

class LinkedListNode
  attr_accessor :value, :next_node

  def initialize(value, next_node=nil)
    @value = value
    @next_node = next_node
  end

end

node1 = LinkedListNode.new(37)
node2 = LinkedListNode.new(99, node1)
node3 = LinkedListNode.new(12, node2)


class Stack
  attr_reader :data

  def initialize
    @data = nil
  end

  def push(value)
    new_top = LinkedListNode.new(value)
    new_top.next_node = @data
    @data = new_top
  end

  def pop
    if @data
      top_value = @data.value
      @data = @data.next_node
      top_value
    else
      nil
    end
  end

end


# mystack = Stack.new
# mystack.push(9)

# 9

# mystack.push(11)

# 11
# 9

# mystack.push(5)

# 5
# 11
# 9

# thing_on_top = mystack.pop
# (now thing_on_top has the value of 5)

# 11
# 9

# thing_on_top = mystack.pop
# (now thing_on_top has the value of 11)

# 9








# print_values(node3)
# at this point, list_node = node3
# print node3.value   (print out 12)

  # print_values(node2)
  # at this point list_node = node2
  # print node2.value   (print out 99)

    # print_values(node1)
    # at this point list_node = node1
    # print node2.value   (print out 37)

      # print_values(nil)
      # at this point list_node = nil
      # print nil
      # return



# They want you to take a list like 1 - 3 - 5 - 9 
# and give back 9 5 3 1

# 9
# 5
# 3
# 1

# pop (9)
# pop (5)
# pop (3)
# pop (1)







def print_values(list_node)
  if list_node
    print "#{list_node.value} --> "
    print_values(list_node.next_node)
  else
    print "nil\n"
    return
  end
end

print_values(node3)







require 'pry'; binding.pry

puts 'all done'