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This article will be continuation of our Linked List tutorial series. You can navigate to other parts from here:

By the end of this article, you shall be able to delete a node at any position of a linked list.

We may be asked to delete a node in a linked list at three different places:

1. delete the first node
2. delete the last node
3. delete the node at a given position

Let us discuss one-by-one along with the coding examples.

##### 1. Delete the first node
1. Create a temp pointer that points to the same node as Head.
2. Move head pointer to the next node and dispose the temp.

In python the temp will be garbage collected when it doesn’t have any reference.

Here’s the code to delete a node at start:

view raw
delete_at_start.py
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##### 2. Delete the Last Node
1. Traverse the list while maintaining previous node’s address also.
2. After reaching the end of the list we will have two pointers -> one pointing to tail node, other pointing to the node before tail node.
3. Update previous node’s next pointer to null
4. Dispose the tail node.

Here’s the code to delete a node at end:

view raw
delete_at_end.py
hosted with ❤ by GitHub

##### 3. Deleting a node at a given position
1. Maintain previous node and the node to be deleted.
2. Once we find the node to be deleted, point the previous node’s pointer to the next pointer of the node to be deleted.
3. Dispose the current node to be deleted.

Here’s the code to delete a node at a given position:

 def delete_at_pos(head, position): if not head: return None if position is 0: return head.next prev_node = head curr_node = head.next current_pos = 1 while curr_node and current_pos < position: current_pos += 1 prev_node = prev_node.next curr_node = curr_node.next prev_node.next = curr_node.next return head

Now let us see the executable code of deletion of Linked list where we can call all the three functions discussed above.

#### Time Complexity

Time complexity for deleting a Node is O(n) where n is the length of linked list, as worst case might be last of the node to be deleted and we need to traversing the entire list.

#### Space Complexity

Space complexity – O(1) for a temp variable.

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