链表（Linked list）是一种常见的基础数据结构，是一种线性表，但是不像顺序表一样连续存储数据，而是每一个结点（数据存储单元）里存放下一个结点的信息（即地址）
# 节点的封装
class Node():
def __init__(self,item):
self.item = item # 向节点中添加的数据值
self.next = None # next是用来指向链表中下一个节点
# 链表的封装
class Link():
def __init__(self):
self._head = None # 头节点
def travel(self): # 遍历整个链表
cur = self._head
while cur:
print(cur.item)
cur = cur.next
def add(self, item): # 链表头部插入节点
node = Node(item)
node.next = self._head
self._head = node
def append(self, item): # 链表尾部追加节点
node = Node(item)
if self._head is None:
self._head = node
return
cur = self._head
while cur.next:
cur = cur.next
cur.next = node
def insert(self, pos, item): # 指定位置插入节点
node = Node(item)
if pos > self.length():
return
if pos == 0:
node.next = self._head
self._head = node
return
pre = None
cur = self._head
for i in range(pos):
pre = cur
cur = cur.next
pre.next = node
node.next = cur
def remove(self, item): # 删除节点
pre = None
cur = self._head
if item == cur.item:
self._head = cur.next
return
while cur:
if cur.item == item:
pre.next = cur.next
break
pre = cur
cur = cur.next
def reverse(self): # 链表的反转
pre = None
cur = self._head
cur_next = cur.next
while cur:
cur.next = pre
pre = cur
cur = cur_next
if cur != None:
cur_next = cur_next.next
self._head = pre
def is_empty(self): # 链表是否为空
return self._head is None
def length(self): # 链表的长度
count = 0
cur = self._head
while cur:
count += 1
cur = cur.next
return count
def search(self, item): # 查找节点是否存在
cur = self._head
find = False
while cur:
if cur.item == item:
find = True
cur = cur.next
return find
链表反转示意图
