这里使用python实现单，双链表。作为简单链表的改进，操作和链表大致相同
单循环链表
"""
@author: LSY123
@file: maina.py
@time: 2020/02/13
@desc: 单项循环链表 单链表的一个变形是单向循环链表，
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.item = item
self.next = None
class SinCycLinkedlist(object):
"""单项循环链表"""
def __init__(self):
self.head = None #头节点记录数据
def is_empty(self):
return self.head == None
def length(self):
if self.is_empty():
return 0
else:
cur = self.head
count = 1
while cur.next != self.head:
count += 1
cur = cur.next
return count
def travel(self):
if self.is_empty() == True:
print("空列表")
cur =self.head
print(cur.item)
cur = cur.next
while cur != self.head:
print(cur.item)
cur = cur.next
def add(self,item): #添加头部节点
node = Node(item)
if self.is_empty() == True:
self.head = node
node.next = node
else:
node.next = self.head #连接头节点
cur = self.head
while cur.next != self.head:
cur = cur.next
cur.next = node
self.head = node
def append(self,item): #尾部添加
node = Node(item)
if self.is_empty() == True:
self.head = node
node.next = node
else:
cur = self.head
while cur.next != self.head:
cur = cur.next
cur.next = node
node.next = self.head
def insert(self,pos,item): #指定位置添加
"""小于0最前添加"""
"""超过指定位置最后添加"""
if self.is_empty() == True and pos <0: #为空或者位置小于0
self.add(item)
return
else:
node = Node(item)
cur = self.head
count = 0
if pos == 0: #当第一个是的
self.add(item)
while cur.next != self.head:
if count == pos-1:
node.next = cur.next
cur.next = node
return
cur = cur.next
self.append(item) #未出现位置
def remove(self,item):
"""根据数值进行数据删除"""
if self.is_empty() == True:
print("空列表")
return
else:
pre = None
cur = self.head
if self.length()==1: #只有一个元素
if cur.item == item:
self.head = None
return
else:
print("未找到待删除元素")
if cur.item == item: #顶头元素是的
while cur.next != self.head:
self.head = self.head.next
cur.next = self.head
return
while cur.next != self.head: #正常情况
if cur.item == item:
pre.next = cur.next
return
else:
pre = cur
cur = cur.next
def search(self, item):
"""查找节点是否存在"""
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
if __name__ == "__main__":
ll = SinCycLinkedlist()
ll.add(1)
ll.add(2)
ll.append(3)
ll.travel()
ll.insert(2, 4)
ll.insert(4, 5)
ll.insert(0, 6)
print("length:", ll.length())
ll.travel()
print(ll.search(3))
print(ll.search(7))
ll.remove(1)
print("length:", ll.length())
ll.travel()
双循环链表
# •is_empty() 链表是否为空
# •length() 链表长度
# •travel() 遍历链表
# •add(item) 链表头部添加
# •append(item) 链表尾部添加
# •insert(pos, item) 指定位置添加
# •remove(item) 删除节点
# •search(item) 查找节点是否存在
class Node(object):
"""双向链表节点"""
def __init__(self, item):
self.item = item
self.next = None
self.prev = None
class DLinkList(object):
"""双向链表"""
def __init__(self):
self._head = None
def is_empty(self):
"""判断链表是否为空"""
return self._head == None
def length(self):
"""返回链表的长度"""
cur = self._head
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历链表"""
cur = self._head
while cur != None:
print cur.item,
cur = cur.next
print ""
def add(self, item):
"""头部插入元素"""
node = Node(item)
if self.is_empty():
# 如果是空链表，将_head指向node
self._head = node
else:
# 将node的next指向_head的头节点
node.next = self._head
# 将_head的头节点的prev指向node
self._head.prev = node
# 将_head 指向node
self._head = node
def append(self, item):
"""尾部插入元素"""
node = Node(item)
if self.is_empty():
# 如果是空链表，将_head指向node
self._head = node
else:
# 移动到链表尾部
cur = self._head
while cur.next != None:
cur = cur.next
# 将尾节点cur的next指向node
cur.next = node
# 将node的prev指向cur
node.prev = cur
def search(self, item):
"""查找元素是否存在"""
cur = self._head
while cur != None:
if cur.item == item:
return True
cur = cur.next
return False
def insert(self, pos, item):
"""在指定位置添加节点"""
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
node = Node(item)
cur = self._head
count = 0
# 移动到指定位置的前一个位置
while count < (pos-1):
count += 1
cur = cur.next
# 将node的prev指向cur
node.prev = cur
# 将node的next指向cur的下一个节点
node.next = cur.next
# 将cur的下一个节点的prev指向node
cur.next.prev = node
# 将cur的next指向node
cur.next = node
def remove(self, item):
"""删除元素"""
if self.is_empty():
return
else:
cur = self._head
if cur.item == item:
# 如果首节点的元素即是要删除的元素
if cur.next == None:
# 如果链表只有这一个节点
self._head = None
else:
# 将第二个节点的prev设置为None
cur.next.prev = None
# 将_head指向第二个节点
self._head = cur.next
return
while cur != None:
if cur.item == item:
# 将cur的前一个节点的next指向cur的后一个节点
cur.prev.next = cur.next
# 将cur的后一个节点的prev指向cur的前一个节点
cur.next.prev = cur.prev
break
cur = cur.next
if __name__ == "__main__":
ll = DLinkList()
ll.add(1)
ll.add(2)
ll.append(3)
ll.insert(2, 4)
ll.insert(4, 5)
ll.insert(0, 6)
print "length:",ll.length()
ll.travel()
print ll.search(3)
print ll.search(4)
ll.remove(1)
print "length:",ll.length()
ll.travel()