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How to search a doubly linked list
P.Praneet
In order to search a Doubly Linked List(DLL) we, first, need a list:
class Nodeq:
def __init__(self, data):
self.data = data
self.next = None
self.prev = NoneNow, we insert the elements into DLL from the definitions insert_beginning and insert_end.
insert_beginningadds a new node element to the beginning of the DLL.insert_endadds a new node element at the end of the DLL.
#Inside the class Dll
def insert_beginning(self,data):
new_node = Nodeq(data)
if(self.head == None): #incase of no Dll create new head
self.head = new_node
return
self.head.prev = new_node
new_node.next = self.head
self.head = new_node # shifting head to new node
def insert_end(self, new_data):
new_node = Nodeq(new_data)
if self.head is None: #incase of no Dll create new head
new_node.prev = None
self.head = new_node
return
last = self.head
while last.next:
last = last.next
last.next = new_node #inserting the new node
new_node.prev = last Next, we check for the presence of the given element and compare it with elements in the DLL.
The
dataelement is required to check.
temp = self.head
while temp:#To check all Dll elements
if temp.data==data:
break
temp = temp.next-
If the element is not found, then the given statement is printed, and
Falseis returned. -
If the element is found, then
Trueis returned.
if gap==None:
print("The given data doesnt exist")
return False
return TrueHence, we get the final code that we can use with other implementations.
class Nodeq:
def __init__(self, data):
self.data = data
self.next = None
self.prev = None
class DoublyLinkedList:
def __init__(self):
self.head = None
def insert_beginning(self,data):
new_node = Nodeq(data)
if(self.head == None): #incase of no Dll create new head
self.head = new_node
return
self.head.prev = new_node
new_node.next = self.head
self.head = new_node # shifting head to new node
def insert_end(self, new_data):
new_node = Nodeq(new_data)
if self.head is None: #incase of no Dll create new head
new_node.prev = None
self.head = new_node
return
last = self.head
while last.next:
last = last.next
last.next = new_node #inserting the new node
new_node.prev = last
def search(self,data):
temp = self.head
while temp:
if temp.data==data:
break
temp = temp.next
if temp==None:
print("The given data doesnt exist:")
return False
return True
#Test case
Dllist = DoublyLinkedList()
Dllist.insert_beginning(2)
Dllist.insert_end(0)
print(Dllist.search(0)) # 0 is present in Dll
print(Dllist.search(3)) # 3 is not present in Dll Code to implement
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