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doublylinkedlist.py
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doublylinkedlist.py
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from __future__ import annotations
class Node:
def __init__(self, value=int, next: Node = None, prev: Node = None) -> None:
self.value = value
self.next = next
self.prev = prev
class DoublyLinkedList:
def __init__(self) -> None:
self.head = None
self.tail = None
self.size = 0
def addBegining(self, data=int) -> None:
if self.head is None and self.tail is None:
node = Node(data)
node.prev = None
self.head = node
else:
current = self.head
new_node = Node(data)
current.prev = new_node
new_node.next = current
self.head = new_node
new_node.prev = None
self.size += 1
def addEnd(self, data=int) -> None:
if self.head is None and self.tail is None:
new_node = self.head = self.tail = Node(data)
new_node.prev = None
else:
current = self.tail
new_node = Node(data)
while current.next:
current = current.next
current.next = new_node
new_node.prev = current
new_node.next = None
self.size += 1
def delete(self, key) -> None:
current = self.head
while current:
if current.value == key and current == self.head:
if current.next is None:
current = None
self.head = None
return
else:
next = current.next
next.prev = None
current.next = None
current = None
self.head = next
return
elif current.value == key:
if current.next != None:
# next_node = current.next
# prev_node = current.prev
# current.prev = None
# next_node.prev = prev_node
# current.next = None
current = None
current.prev = None
current.next = None
return
else:
prev = current.prev
prev.next = None
current.prev = None
current = None
return
current = current.next
self.size -= 1
def display(self) -> None:
if self.head is None and self.tail is None:
raise ValueError('Linked list is empty')
current = self.head
while current is not None:
# if current.prev is not None:
# print('->', previous.value, current.value, end='')
print(current.value, end='')
if current.next is not None:
print(' -> ', end='')
previous = current.prev
current = current.next
print(' ')
def print_list(self):
cur = self.head
while cur:
print(cur.value)
cur = cur.next
dll = DoublyLinkedList()
dll.addBegining(2)
dll.addBegining(3)
dll.addBegining(13)
dll.addBegining(5)
dll.addBegining(10)
# dll.delete(13)
dll.print_list()