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doublylinkedlist.py
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doublylinkedlist.py
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class node:
def __init__(self, data):
self.data = data
self.next = None
self.prev = None
class DLList:
def __init__(self):
self.head = None
def insertfront(self, data):
newnode = node(data)
if (self.head is not None):
self.head.prev = newnode
newnode.next = self.head
self.head = newnode
def insertend(self, data):
newnode = node(data)
newnode.next = None
if self.head is None:
self.head = newnode
return
t = self.head
while (t.next is not None):
t = t.next
t.next = newnode
newnode.prev = t
def insertAfter(self, data, x):
newnode = node(data)
if (self.head):
l = self.head
while (l and l.data != x):
l = l.next
if (l.data == x):
newnode.next = l.next
l.next = newnode
def deletefront(self):
if (self.head):
t = self.head
self.head = t.next
del t
if(self.head):
self.head.prev = None
def display(self):
t = self.head
while(t):
print(t.data)
t = t.next
def deleteEnd(self):
if (self.head):
t = self.head
while (t.next and t.next.next):
t = t.next
if (t.next is None):
self.head = None
return
del t.next
t.next = None
def deleteAfter(self, x):
if (self.head):
l = self.head
while (l and l.data != x):
l = l.next
if (l and l.next.next and l.data == x):
l.next = l.next.next
t = l
l = l.next
l.prev = t
elif (l):
l.next = None
dll = DLList()
while (1):
print("1.insert front")
print("2.insert back")
print("3.insert after ")
print("4.delete")
print("5.delete end")
print("6. delete after")
print("7.display")
print("8exit")
ch = input("enter your choice:")
if ch == "1":
x = int(input("enter the data"))
dll.insertfront(x)
elif ch == "2":
x = int(input("enter the data"))
dll.insertend(x)
elif ch == "3":
x = int(input("Enter data:"))
a = int(input("Enter data before:"))
dll.insertAfter(x, a)
elif ch == "4":
dll.deletefront()
elif ch == "5":
dll.deleteEnd()
elif ch == "6":
x = int(input("Enter data before:"))
dll.deleteAfter(x)
elif ch == "7":
dll.display()
elif ch == "8":
break