Question

PYTHON-- how do i change these linkedlist methods into doublylinkedlist methods? A doublylinked list is the same as a linked list, except that each node has a reference to the node after it(next) and the node before it(prev). 

#adds item to the head of list.
def add(self, item):
   
    node = Node(item, self.head)  
   
    self.head = node  
    if self.size == 0:  
        self.tail = node
    self.size += 1

#appends item to tail of list
def append(self, item):

    node = Node(item)
    tail = self.head
    node.next = None
    if self.size == 0:
        node.prev = None
        self.head = node
        return

    while tail.next is not None:
        tail = tail.next

    tail.next = node
    node.prev = tail
    self.size += 1   

#removes the node at position pos. returns node's data
 #make pop O(1)

def pop(self, pos=None):
    
    current = self.head
    previous = None

    i = 0
    while current != None and i != pos:
        previous = current
        current = current.next
        i += 1

if current == self.tail:
    previous.next = None
    self.tail = previous
    self.size -= 1
    return current.data
elif prev is None:
    if self.size == 1:
        self.tail = None
    self.head = current.next
    self.size -= 1
    return current.data
else:
    previous.next = current.next
    self.size -= 1
    return current.data

Answer 1

PLEASE GIVE IT A THUMBS UP, I SERIOUSLY NEED ONE, IF YOU NEED ANY MODIFICATION THEN LET ME KNOW, I WILL DO IT FOR YOU

class Node:
    def __init__(self, item):

        self.item = item
        self.next = None
        self.prev = None
    
class DoubleLinkedList:
    def __init__(self):

        self.dllnode = None
    # adds item to the head of list

    def add(self, item):

        if(self.dllnode == None):
            new_node = Node(item)
            self.dllnode = new_node
        new_node = Node(item)
        new_node.next = self.dllnode
        self.dllnode.prev = new_node
        self.dllnode = new_node

        # adds item to the end of list

    def append(self, item):

        new_node = Node(item)
        new_node.next = None
        if self.dllnode is None:
            new_node.prev = None
            self.dllnode = new_node
            return
        temp = self.dllnode
        if temp.next is not None:
            temp = temp.next
        temp.next = new_node
        new_node.prev = temp

        # print list

    def printList(self):

        while(self.dllnode is not None):
            print(self.dllnode.item, end="->")
            self.dllnode = self.dllnode.next
        # removes the node at position pos return node data

    def pop(self, pos):

        if(self.dllnode is None):
            return
        cur = self.dllnode
        i = 1
        while(cur != None and i != pos):
            cur = cur.next
            i = i+1
            if(cur == None):
                return

        # node to be deleted
        if(self.dllnode == None or cur == None):
            return
        # if the node is the first or head node
        if(self.dllnode == cur):
            self.dllnode = cur.next
        # if the node is the last node
        if(cur.next is not None):
            cur.next.prev = cur.prev
        if(cur.prev is not None):
            cur.prev.next = cur.next
            return self.dllnode.item


node = DoubleLinkedList()

node.add(20)
node.add(30)
node.append(50)
print(node.pop(2))
print(node.printList())