def add(self, data):
newNode = Node(data)
if self.isEmpty():
self.__head = newNode
else:
newNode.setNext(self.__head)
self.__head.setPrev(newNode)
self.__head = newNode
def append(self, data):
newNode = Node(data)
if self.isEmpty():
self.add(data)
else:
newNode.setNext(self.__head)
# head的前驱就是链表尾部
newNode.setPrev(self.__head.getPrev())
self.__head.getPrev().setNext(newNode)
self.__head.setPrev(newNode)
def insert(self, data, pos=0):
if pos <= 0:
self.add(data)
elif pos > self.size() - 1:
self.append(data)
else:
newNode = Node(data)
preHead = self.__head
count = 0
# preHead指向指定位置前一个位置pos-1
while count < pos - 1:
count += 1
preHead = preHead.getNext()
newNode.setPrev(preHead)
newNode.setNext(preHead.getNext())
preHead.getNext().setPrev(newNode)
preHead.setNext(newNode)