infinity_ll.rb

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

def infinity_loop(list)
  slow = list 
  fast = list
  until slow.next_node.nil? or fast.next_node.nil? do 
    slow = slow.next_node
    fast = fast.next_node.next_node
    return true if (slow == fast)
  end
    false
end

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

#print_values(node3)
puts infinity_loop(node3)