Python Program for Deleting a Node in a Linked List
Last Updated :
24 Apr, 2023
We have discussed Linked List Introduction and Linked List Insertion in previous posts on a singly linked list.
Let us formulate the problem statement to understand the deletion process. Given a ‘key’, delete the first occurrence of this key in the linked list.
Iterative Method:
To delete a node from the linked list, we need to do the following steps.
1) Find the previous node of the node to be deleted.
2) Change the next of the previous node.
3) Free memory for the node to be deleted.
Since every node of the linked list is dynamically allocated using malloc() in C, we need to call free() for freeing memory allocated for the node to be deleted.
Python3
class Node:
def __init__( self , data):
self .data = data
self . next = None
class LinkedList:
def __init__( self ):
self .head = None
def push( self , new_data):
new_node = Node(new_data)
new_node. next = self .head
self .head = new_node
def deleteNode( self , key):
temp = self .head
if (temp is not None ):
if (temp.data = = key):
self .head = temp. next
temp = None
return
while (temp is not None ):
if temp.data = = key:
break
prev = temp
temp = temp. next
if (temp = = None ):
return
prev. next = temp. next
temp = None
def printList( self ):
temp = self .head
while (temp):
print ( " %d" % (temp.data)),
temp = temp. next
llist = LinkedList()
llist.push( 7 )
llist.push( 1 )
llist.push( 3 )
llist.push( 2 )
print ( "Created Linked List: " )
llist.printList()
llist.deleteNode( 1 )
print ( "Linked List after Deletion of 1:" )
llist.printList()
|
Output
Created Linked List:
2
3
1
7
Linked List after Deletion of 1:
2
3
7
Time Complexity: O(n), where n represents the length of the given linked list.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
Please refer complete article on Linked List | Set 3 (Deleting a node) for more details!
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