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
# A complete working Python3 program to# demonstrate deletion in singly# linked list with class# Node classclass Node: # Constructor to initialize the node object def __init__(self, data): self.data = data self.next = Noneclass LinkedList: # Function to initialize head def __init__(self): self.head = None # Function to insert a new node at the beginning def push(self, new_data): new_node = Node(new_data) new_node.next = self.head self.head = new_node # Given a reference to the head of a list and a key, # delete the first occurrence of key in linked list def deleteNode(self, key): # Store head node temp = self.head # If head node itself holds the key to be deleted if (temp is not None): if (temp.data == key): self.head = temp.next 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 # Unlink the node from linked list prev.next = temp.next temp = None # Utility function to print the linked LinkedList def printList(self): temp = self.head while(temp): print (" %d" %(temp.data)), temp = temp.next# Driver programllist = 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()# This code is contributed by Nikhil Kumar Singh (nickzuck_007) & edited by Sayan Biswas (dankguy6146) |
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!
