双向链表
- 后继节点:指向下一个节点
- 前驱节点:指向前一个节点
- 头节点没有前驱节点,尾节点没有后继节点
实现功能
该代码实现的主要是双向链表
的几个常规操作
- is_empty()
- length()
- travel()
- add()
- append()
- insert()
- remove()
- search()
代码实现
class Node(object):
def __init__(self, item):
self.elem = item
self.next = None
self.prev = None
class DoubleLinkList(object):
def __init__(self, node=None):
self.__head = node
def is_empty(self):
return self.__head is None
def length(self):
cur = self.__head
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
cur = self.__head
while cur != None:
print(cur.elem, end=" ")
cur = cur.next
print("")
def add(self, item):
node = Node(item)
node.next = self.__head
self.__head = node
node.next.prev = node
def append(self, item):
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
node.prev = cur
def insert(self, pos, item):
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
cur = self.__head
count = 0
while count < pos:
count += 1
cur = cur.next
node = Node(item)
node.next = cur
node.prev = cur.prev
cur.prev.next = node
cur.prev = node
def remove(self, item):
cur = self.__head
while cur != None:
if cur.elem == item:
if cur == self.__head:
self.__head = cur.next
if cur.next:
cur.next.prev = None
else:
cur.prev.next = cur.next
if cur.next:
cur.next.prev = cur.prev
break
else:
cur = cur.next
def search(self, item):
cur = self.__head
while cur != None:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == "__main__":
li = DoubleLinkList()
print(li.is_empty())
print(li.length())
li.append(1)
print(li.is_empty())
print(li.length())
li.append(2)
li.append(4)
li.add(8)
li.append(5)
li.insert(-1,9)
li.travel()
li.insert(4,11)
li.travel()
li.insert(15,12)
li.travel()
li.remove(9)
li.travel()
li.remove(4)
li.travel()
li.remove(12)
li.travel()