然后sa地方打工啊啊哥但是更合适地方
大哥十多个
阿桑的歌
- '''''
-
- A linked list is similar to an array, it holds values. However, links in a linked list do not have indexes.
-
- This is an example of a double ended, doubly linked list.
-
- Each link references the next link and the previous one.
-
- A Doubly Linked List (DLL) contains an extra pointer, typically called previous pointer, together with next pointer and data which are there in singly linked list.
-
- Advantages over SLL - IT can be traversed in both forward and backward direction.,Delete operation is more efficent'''
- class LinkedList: #making main class named linked list
**def** \_\_init\_\_(self):
self.head = None
self.tail = None
**def** insertHead(self, x):
newLink = Link(x) #Create a new link with a value attached to it
**if** (self.isEmpty() == True): #Set the first element added to be the tail
self.tail = newLink
**else** :
self.head.previous = newLink # newLink \<-- currenthead(head)
newLink.next = self.head # newLink \<--\> currenthead(head)
self.head = newLink # newLink(head) \<--\> oldhead
**def** deleteHead(self):
temp = self.head
self.head = self.head.next # oldHead \<--\> 2ndElement(head)
self.head.previous = None # oldHead --\> 2ndElement(head) nothing pointing at it so the old head will be removed
**if** (self.head **is** None):
self.tail = None #if empty linked list
**return** temp
**def** insertTail(self, x):
newLink = Link(x)
newLink.next = None # currentTail(tail) newLink --\>
self.tail.next = newLink # currentTail(tail) --\> newLink --\>
newLink.previous = self.tail #currentTail(tail) \<--\> newLink --\>
self.tail = newLink # oldTail \<--\> newLink(tail) --\>
**def** deleteTail(self):
temp = self.tail
self.tail = self.tail.previous # 2ndLast(tail) \<--\> oldTail --\> None
self.tail.next = None # 2ndlast(tail) --\> None
**return** temp
**def** delete(self, x):
current = self.head
**while** (current.value != x): # Find the position to delete
current = current.next
**if** (current == self.head):
self.deleteHead()
**elif** (current == self.tail):
self.deleteTail()
**else** : #Before: 1 \<--\> 2(current) \<--\> 3
current.previous.next = current.next # 1 --\> 3
current.next.previous = current.previous # 1 \<--\> 3
**def** isEmpty(self): #Will return True if the list is empty
**return** (self.head **is** None)
**def** display(self): #Prints contents of the list
current = self.head
**while** (current != None):
current.displayLink()
current = current.next
**print** ()
- class Link:
next = None #This points to the link in front of the new link
previous = None #This points to the link behind the new link
**def** \_\_init\_\_(self, x):
self.value = x
**def** displayLink(self):
**print** ("{}".format(self.value), end=" ")