# Python Algorithm – Deleting a node in Linked List | Set 3

Python Algorithm - Deleting a node in Linked List - Linked List - We have discussed Linked List Introduction and Linked List Insertion in previous

We have discussed Linked List Introduction and Linked List Insertion in previous posts on 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 linked list.
To delete a node from linked list, we need to do following steps.
1) Find previous node of the node to be deleted.
2) Changed next of previous node.
3) Free memory for the node to be deleted.

Since every node of linked list is dynamically allocated using malloc() in C, we need to call free() for freeing memory allocated for the node to be deleted.

Python Programming:

``````# Python program to delete a node from linked list

# Node class
class Node:

# Constructor to initialize the node object
def __init__(self, data):
self.data = data
self.next = None

def __init__(self):

# Function to insert a new node at the beginning
def push(self, new_data):
new_node = Node(new_data)

# Given a reference to the head of a list and a key,
# delete the first occurence of key in linked list
def deleteNode(self, key):

# If head node itself holds the key to be deleted
if (temp is not None):
if (temp.data == key):
temp = None
return

# Search for the key to be deleted, keep track of the
# previous node as we need to change 'prev.next'
while(temp is not None):
if temp.data == key:
break
prev = temp
temp = temp.next

# if key was not present in linked list
if(temp == None):
return

prev.next = temp.next

temp = None

def printList(self):
while(temp):
print " %d" %(temp.data),
temp = temp.next

# Driver program
llist.push(7)
llist.push(1)
llist.push(3)
llist.push(2)

llist.printList()
llist.deleteNode(1)
print "\nLinked List after Deletion of 1:"
llist.printList()

# This code is contributed by Nikhil Kumar Singh (nickzuck_007)``````

Output:

```Created Linked List:
2  3  1  7
Linked List after Deletion of 1:
2  3  7```