Doubly Linked Lists- Add Node Before and After
Code:
class Node:
def __init__(self, data):
self.data = data
self.next = None
self.prev = None
class DoublyLinkedList:
def __init__(self):
self.head = None
def append(self, data):
if self.head is None:
new_node = Node(data)
new_node.prev = None
self.head = new_node
else:
new_node = Node(data)
cur = self.head
while cur.next:
cur = cur.next
cur.next = new_node
new_node.prev = cur
new_node.next = None
def prepend(self, data):
if self.head is None:
new_node = Node(data)
new_node.next = self.head
self.head = new_node
else:
new_node = Node(data)
self.head.prev = new_node
new_node.next = self.head
self.head = new_node
def add_after_node(self, key, data):
current = self.head
while current:
if current.next is None and current.data == key: # Case One
self.append(data)
return
elif current.data == key:
new_node = Node(data)
nxt = current.next
current.next = new_node
new_node.next = nxt
nxt.previous = new_node
new_node.prev = current
current = current.next
def add_before_node(self, key, data):
current = self.head
while current:
if current.prev is None and current.data == key:
self.prepend(data)
elif current.data == key:
new_node = Node(data)
prev = current.prev
prev.next = new_node
current.prev = new_node
new_node.next = current
new_node.prev = prev
current = current.next
def print_list(self):
cur = self.head
while cur:
print(cur.data)
cur = cur.next