The core values of Chinese socialism
单向循环链表
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cur != None->cur != head
class SingleNode(object):
def __init__(self, item):
self.item = item
self.next = None
class SingleCycLinkedlist(object):
def __init__(self):
self._head = None
def isEmpty(self):
return self._head == None
def length(self):
if self.isEmpty():
return 0
count = 1
cur = self._head
while cur.next != self._head:
count += 1
cur = cur.next
return count
def travel(self):
if self.isEmpty():
return
cur = self._head
print(cur.item)
while cur.next != self._head:
cur = cur.next
print(cur.item)
def addFirst(self, item):
node = SingleNode(item)
if self.isEmpty():
self._head = node
node.next = self._head
else:
node.next = self._head
cur = self._head
while cur.next != self._head:
cur = cur.next
cur.next = node
self._head = node
def append(self, item):
node = SingleNode(item)
if self.isEmpty():
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.addFirst(item)
elif pos > (self.length()-1):
self.append(item)
else:
node = SingleNode(item)
cur = self._head
count = 0
while count < (pos-1):
count += 1
cur = cur.next
node.next = cur.next
cur.next = node
def remove(self, item):
if self.isEmpty():
return
cur = self._head
pre = None
if cur.item == item:
if cur.next != self._head:
while cur.next != self._head:
cur = cur.next
cur.next = self._head.next
self._head = self._head.next
else:
self._head = None
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(self, item):
if self.isEmpty():
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
if __name__ == "__main__":
ll = SingleCycLinkedlist()
ll.addFirst(1)
ll.addFirst(2)
ll.append(3)
ll.insert(2, 4)
ll.insert(4, 5)
ll.insert(0, 6)
print("length: {0}".format(ll.length()))
ll.travel()
print(ll.search(3))
print(ll.search(7))
ll.remove(1)
print("length:",ll.length())
ll.travel()
length: 6
6
2
1
4
3
5
True
False
length: 5
6
2
4
3
5
