2.7_linked_list_链表的创建和遍历

class Node(object):
    """节点类"""

    def __init__(self, item):
        self.item = item
        self.next = None

def create_linkedlist_head(li):
    """从 head 处链接"""

    head = Node(li[0])

    for element in li[1:]:
        node = Node(element)
        node.next = head
        head = node

    return head

def create_linkedlist_tail(li):
    """从 tail 处链接"""

    head = Node(li[0])
    tail = head

    for element in li[1:]:
        node = Node(element)
        tail.next = node
        tail = node

    return head

def print_linkedlist(lk):
    """链表的遍历"""

    while lk:
        print(lk.item, end=',')
        lk = lk.next