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item-4.py
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item-4.py
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class Node:
def __init__(self, data):
self.data = data
self.next = None
self.prev = None
class DoublyLinkedList:
def __init__(self):
self.head = None
self.tail = None
self.size = 0
def __len__(self):
return self.size
def __str__(self):
s=''
p = self.head
while p != None :
if p != self.tail:
s += str(p.data) + '->'
else:
s += str(p.data)
p = p.next
return s
def str_reverse(self):
s = ''
p=self.tail
while p != None :
if p != self.head:
s += str(p.data) + '->'
else:
s += str(p.data)
p = p.prev
return s
def isEmpty(self):
if self.size == 0 :
return True
else:
return False
def append(self, data):
temp = Node(data)
if self.head == None:
self.head = temp
self.tail = temp
else:
self.tail.next=temp
temp.prev = self.tail
self.tail = self.tail.next
self.size += 1
def insert(self, index, data):
i = 0
temp = Node(data)
p = self.head
if index == 0:
if(self.isEmpty()):
self.head = temp
self.tail = temp
else:
self.head.prev = temp
temp.next = self.head
self.head = temp
elif index == len(self):
self.append(data)
else:
while i != index:
if i == index - 1:
temp.prev = p
temp.next = p.next
p.next.prev = temp
p.next = temp
else:
p = p.next
i += 1
self.size += 1
def remove(self,data):
p = self.head
i = 0
while p != None:
if p.data == data:
if p != self.head and p != self.tail:
p.prev.next = p.next
p.next.prev = p.prev
p.prev = None
p.next = None
elif p == self.head and self.head != self.tail:
p.next.prev = None
self.head = p.next
p.next = None
elif p == self.tail and self.head != self.tail:
p.prev.next = None
self.tail = p.prev
p.prev = None
else :
self.head = None
self.tail = None
self.size -= 1
return [p,i]
p = p.next
i += 1
return [None]