Given a singly linked list and a position, delete a linked list node at the given position.
Example:
Input: position = 1, Linked List = 8->2->3->1->7 Output: Linked List = 8->3->1->7 Input: position = 0, Linked List = 8->2->3->1->7 Output: Linked List = 2->3->1->7
If the node to be deleted is the root, simply delete it. To delete a middle node, we must have a pointer to the node previous to the node to be deleted. So if positions are not zero, we run a loop position-1 times and get a pointer to the previous node.
Below is the implementation of the above idea.
// A complete working Java program to delete a node in a linked list // at a given position class LinkedList
{ Node head; // head of list
/* Linked list Node*/
class Node
{
int data;
Node next;
Node( int d)
{
data = d;
next = null ;
}
}
/* Inserts a new Node at front of the list. */
public void push( int new_data)
{
/* 1 & 2: Allocate the Node &
Put in the data*/
Node new_node = new Node(new_data);
/* 3. Make next of new Node as head */
new_node.next = head;
/* 4. Move the head to point to new Node */
head = new_node;
}
/* Given a reference (pointer to pointer) to the head of a list
and a position, deletes the node at the given position */
void deleteNode( int position)
{
// If linked list is empty
if (head == null )
return ;
// Store head node
Node temp = head;
// If head needs to be removed
if (position == 0 )
{
head = temp.next; // Change head
return ;
}
// Find previous node of the node to be deleted
for ( int i= 0 ; temp!= null && i<position- 1 ; i++)
temp = temp.next;
// If position is more than number of nodes
if (temp == null || temp.next == null )
return ;
// Node temp->next is the node to be deleted
// Store pointer to the next of node to be deleted
Node next = temp.next.next;
temp.next = next; // Unlink the deleted node from list
}
/* This function prints contents of linked list starting from
the given node */
public void printList()
{
Node tnode = head;
while (tnode != null )
{
System.out.print(tnode.data+ " " );
tnode = tnode.next;
}
}
/* Driver program to test above functions. Ideally this function
should be in a separate user class. It is kept here to keep
code compact */
public static void main(String[] args)
{
/* Start with the empty list */
LinkedList llist = new LinkedList();
llist.push( 7 );
llist.push( 1 );
llist.push( 3 );
llist.push( 2 );
llist.push( 8 );
System.out.println("
Created Linked list is: "); llist.printList();
llist.deleteNode( 4 ); // Delete node at position 4
System.out.println("
Linked List after Deletion at position 4 : ");
llist.printList();
}
} |
Output:
Created Linked List: 8 2 3 1 7 Linked List after Deletion at position 4: 8 2 3 1
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 Delete a Linked List node at a given position for more details!