简单实现单向循环链表
链表操作
- is_empty() 判断链表是否为空
- length() 返回链表的长度
- travel() 遍历
- add(item) 在头部添加一个节点
- append(item) 在尾部添加一个节点
- insert(pos, item) 在指定位置pos添加节点
- remove(item) 删除一个节点
- search(item) 查找节点是否存在
class Node(object):
def __init__(self, item):
self.item = item
self.next = None
class SinCycLinkList(object):
"""单向循环链表"""
def __init__(self):
self.__head = None
def is_empty(self):
"""判断是否为空"""
return self.__head == None
def length(self):
"""返回链表的长度"""
if self.is_empty():
return 0
count = 1
cur = self.__head
while cur.next != self.__head:
cur = cur.next
count += 1
return count
def travel(self):
"""遍历链表"""
if self.is_empty():
return
cur = self.__head
print(cur.item)
while cur.next != self.__head:
cur = cur.next
print(cur.item)
print("", end="")
def add(self, item):
"""头部添加元素"""
node = Node(item)
if self.is_empty():
self.__head = node
node.next = self.__head
else:
# 添加的节点指向_head
node.next = self.__head
# 移动到链表尾部
cur = self.__head
while cur.next != self.__head:
cur = cur.next
cur.next = node
# 将头_head指向node
self.__head = node
def append(self, item):
"""尾部添加元素"""
node = Node(item)
if self.is_empty():
self.__head = node
node.next = self.__head
else:
# 移动到链表底部
cur = self.__head
while cur.next != self.__head:
cur = cur.next
# 将尾节点指向node
cur.next = node
# 将node节点指向_head
node.next = self.__head
def insert(self, pos, item):
"""指定位置添加元素"""
if pos <= 0:
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
node = Node(item)
cur = self.__head
count = 0
# 移动到指定位置前一个
while count < (pos - 1):
cur = cur.next
count += 1
node.next = cur.next
cur.next = node
def remove(self, item):
"""删除节点"""
if self.is_empty():
return
else:
# 将cur指向头节点
cur = self.__head
pre = None
while cur.next != self.__head:
if cur.item == item:
# 判断此节点是否是头节点
# 头节点的情况
if cur == self.__head:
# 找到尾节点
rear = self.__head
while rear.next != self.__head:
rear = rear.next
# 头节点指向cur的next
self.__head = cur.next
rear.next = self.__head
else:
# 中间节点
pre.next = cur.next
return
else:
pre = cur
cur = cur.next
# 退出循环，cur指向尾节点
if cur.item == item:
if cur == self.__head:
# 链表只有一个节点
self.__head = None
else:
pre.next = self.__head
def search(self, item):
"""查找节点元素是否存在"""
if self.is_empty():
return False
cur = self.__head
if cur.item == item:
return True
while cur.next != self.__head:
cur = cur.next
if cur.item == item:
return True
return False