Python写数据结构:单向循环链表

#!/usr/bin/python3.5
# _*_coding:utf-8_*_

class Node:
def __init__(self, value):
self.data = value
self.next = None

class CycleList:
def __init__(self):
self._head = Node(None)
self._head.next = self._head
self.rear = self._head

def insert(self, index, value):
n = Node(value)
cur = self._head
for i in range(index - 1):
cur = cur.next
n.next = cur.next
cur.next = n
if n.next == self._head:
self.rear = n

def remove(self, index):
if index <= 0 or index > self.length():
print('删除位置有误')
return
cur = self._head
for i in range(index - 1):
cur = cur.next
if cur == None:
print('删除位置有误')
return
n = cur.next
cur.next = cur.next.next
del n
if cur.next == self._head:
self.rear = cur

def empty(self):
return self._head.next == self._head

def search(self, value):
cur = self._head.next
index = 1
while cur != self._head and cur.data != value:
cur = cur.next
index += 1
if cur == self._head:
print('没有该元素')
return
print("index:%d,value:%d" % (index, value))

def clear(self):
cur = self._head.next
while cur != self._head:
n = cur
cur = cur.next
del n
self._head.next = self._head
self.rear = self._head

def length(self):
count = 0
cur = self._head.next
while cur != self._head:
count += 1
cur = cur.next
return count

def travel(self):
if self.empty():
print('空')
return
cur = self._head
while cur.next != self._head:
cur = cur.next
print(cur.data)

def appendhead(self, value):
n = Node(value)
if self.empty():
self.rear = n
n.next = self._head.next
self._head.next = n

def appendrear(self, value):
n = Node(value)
n.next = self.rear.next
self.rear.next = n
self.rear = n

if __name__ == '__main__':
link = CycleList()