linked_list_with_stack_azat.rb

#!/usr/bin/env ruby

class LinkedListNode
  attr_accessor :value, :next_node

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


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


class Stack
    attr_reader :data

    def initialize
      @data = nil
    end

    # Push a value onto the stack
    def push(value)
      my_node = LinkedListNode.new(value, @data)
      @data = my_node
    end
    
    # Pop an item off the stack.
    # Remove the last item that was pushed onto the
    # stack and return the value to the user
    def pop
      top_node = @data
      @data = top_node.next_node
      return top_node
    end
end





def reverse_list(list_node)
  my_stack = Stack.new
 
  while list_node != nil
    # push each value into the linked list stack
    my_stack.push(list_node.value)
    # move to the next value (will finish looping when next_node is nil)
    list_node = list_node.next_node
  end

  return my_stack.pop
end

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

print_values(node3)

puts "-------"

reversed_list = reverse_list(node3)

print_values(reversed_list)