def append(self, elem):
if self.head is None:
self.head = LNode(elem, None)
return
p = self.head
while p.next is not None:
p = p.next
p.next = LNode(elem, None)
def prepend(self, elem): # add element in the front end
p = LNode(elem, None)
if self.rear is None:
p.next = p # 表中第一个结点建立初始的循环链接
self.rear = p
else:
p.next = self.rear.next # 链在尾结点之后，就是新的首结点
self.rear.next = p
def prepend(self, elem):
self.head = LNode(elem, self.head)
def __init__(self, prev, elem, nxt):
LNode.__init__(self, elem, nxt)
self.prev = prev # 扩充了一个前一结点指针
def append(self, elem):
if self.rear is None: # empty list
self.prepend(elem)
else:
self.rear.next = LNode(elem, None)
self.rear = self.rear.next
def prepend(self, elem):
self.head = LNode(elem, self.head)
if self.rear is None: # empty list
self.rear = self.head