"""
 links.py
 A linked list in python. 
 Run this at pythontutor.com to see what's going on.

   $ python links.py
   1 -> 2 -> 3 -> 

 Jim M | Feb 6 | cs.bennington.college | MIT License
"""

class Node:
    """ one node in a linked list """
    def __init__(self, value, next=None):
        self.value = value
        self.next = next

def print_nodes(node):
    """ print a list starting at a given node """
    while node:
        print(f"{node.value} -> ", end="")
        node = node.next
    print()
    
def length_nodes_1(node):
    """ return the lenght of the linked list that starts at node """
    # This version 1 uses an explicit loop
    length = 0
    while node:
        length = length + 1
        node = node.next
    return length

def length_nodes_2(node):
    """ return the length of the linked list that starts at node """
    # This version 2 uses recursion!!!
    if node:
        return 1 + length_nodes_2(node.next)
    else:
        return 0
        
def main():

    # Create a linked list :  1 -> 2 -> 3
    three = Node(3)
    two = Node(2, three)
    one = Node(1, two)

    print_nodes(one)
    
    print(f"The length of the list is {length_nodes_1(one)}.")

    print(f"The length of the list is (again) {length_nodes_2(one)}.")

    
main()