链表

class Node:
    def __init__(self, val = None, next = None):
        self.val = val
        self.next = next

def create_link(link):
    root = Node(link[0])
    pre = root
    for i in range(1, len(link)):
        p = Node(link[i])
        pre.next = p
        pre = p
    return root

def print_link(root):
    p = root
    while p:
        print(p.val, end=",")
        p = p.next
    print()

link = [1, 3, 9, 2]
link_root = create_link(link)
print_link(link_root)