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SinCycLink.py
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SinCycLink.py
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'''
单向循环链表,链表中最后一个节点的next域不再为None,而是指向链表的头节点。
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):
"""节点"""
def __init__(self, item):
self.next = None
self.item = item
class SinCycLinkList(object):
"""单向循环列表"""
def __init__(self):
self._head = None
def is_empty(self):
return self._head == None
def length(self):
if self.is_empty():
return 0
else:
count = 1
cur = self._head
while cur.next != self._head:
count += 1
cur = cur.next
return count
def travel(self):
if self.is_empty():
return
else:
cur = self._head
print(cur.item)
while cur.next != self._head:
cur = cur.next
print(cur.item)
print('')
def add(self,item):
'''头部添加节点'''
node = Node(item)
if self.is_empty():
self._head = node
node.next = self._head
else:
node.next = self._head
# 找到尾节点
cur = self._head
while cur.next!=self._head:
cur = cur.next
# 尾节点指向Node
cur.next = node
#_head指向添加的node
self._head = node
def append(self,item):
node = Node(item)
if self.is_empty():
self._head = node
node.next = self._head
else:
cur = self._head
while cur.next!=self._head:
cur = cur.next
cur.next = node
node.next = self._head
def insert(self,pos,item):
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
node = Node(item)
cur = self._head
count = 0
while count < (count-1):
count+=1
cur = cur.next
node.next = cur.next
cur.next = node
def remove(self,item):
if self.is_empty():
return
else:
cur = self._head
pre = Node
# 第一个节点元素就是要删除元素
if cur.item == item:
# 链表不知一个元素
if cur.next!=self._head:
# 找到尾节点指向第二个元素
while cur.next!=sel._head:
cur = cur.next
cur.next = self._head.next
self._head = self._head.next
else:
self._head = Node
# 首节点不是要删除的元素
else:
pre = self._head
while cur.next!=self._head:
if cur.item == item:
pre.next=cur.next
return
else:
pre = cur
cur = cur.next
if cur.item==item:
pre.next = cur.next
def search(item):
if self.is_empty():
return False
cur = self._head
if cur.item==item:
return True
else:
while cur.next!=self._head:
cur = cur.next
if cur.item==item:
return True
return False
# 测试
if __name__ == '__main__':
ll = SinCycLinkList()
ll.append(1)
ll.append(2)
ll.append(4)
ll.insert(2,3)
ll.add(0)
ll.travel()
print("链表长度:",ll.length())
ll.remove(2)
ll.travel()