reverse_linked_list.rb

class Node
    attr_accessor :next
    attr_accessor :value
end

def traverse_linked_list(start_node)
    current_node = start_node
    while current_node != nil do
        puts "VALUE #{current_node.value}"
        current_node = current_node.next
    end
end

def reverse_linked_list(start_node)
    current_node = start_node
    previous = nil
    while current_node != nil
        # store the next pointer into temp
        temp = current_node.next
        # set the current next to the previous
        current_node.next = previous
        # update the previous node to the current node 
        previous = current_node
        # move to next node which has been saved in temp
        current_node = temp
    end
end

node_c = Node.new
node_c.value = "C"
node_c.next = nil

node_b = Node.new
node_b.value = "B"
node_b.next = node_c

node_a = Node.new
node_a.value = "A"
node_a.next = node_b

traverse_linked_list(node_a)
reverse_linked_list(node_a)
traverse_linked_list(node_c)