Deletion in Singly Linked List After Specified Node

Deletion in Singly Linked List After Specified Node with Introduction, Asymptotic Analysis, Array, Pointer, Structure, Singly Linked List, Doubly Linked List, Circular Linked List, Binary Search, Linear Search, Sorting, Bucket Sort, Comb Sort, Shell Sort, Heap Sort, Merge Sort, Selection Sort, Counting Sort, Stack, Qene, Circular Quene, Graph, Tree, B Tree, B+ Tree, Avl Tree etc.

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Deletion in singly linked list after the specified node :

In order to delete the node, which is present after the specified node, we need to skip the desired number of nodes to reach the node after which the node will be deleted. We need to keep track of the two nodes. The one which is to be deleted the other one if the node which is present before that node. For this purpose, two pointers are used: ptr and ptr1.

Use the following statements to do so.

ptr=head;
		for(i=0;i<loc;i++)
		{
			ptr1 = ptr;		
			ptr = ptr->next;
			
			if(ptr == NULL)
			{
				printf("\nThere are less than %d elements in the list..",loc);
				return;
			}
		}

Now, our task is almost done, we just need to make a few pointer adjustments. Make the next of ptr1 (points to the specified node) point to the next of ptr (the node which is to be deleted).

This will be done by using the following statements.

ptr1 ->next = ptr ->next;
		free(ptr);

Algorithm

STEP 1: IF HEAD = NULL

WRITE UNDERFLOW
GOTO STEP 10
END OF IF

STEP 2: SET TEMP = HEAD
STEP 3: SET I = 0
STEP 4: REPEAT STEP 5 TO 8 UNTIL I
STEP 5: TEMP1 = TEMP
STEP 6: TEMP = TEMP → NEXT
STEP 7: IF TEMP = NULL

WRITE "DESIRED NODE NOT PRESENT"
GOTO STEP 12
END OF IF

STEP 8: I = I+1

END OF LOOP

STEP 9: TEMP1 → NEXT = TEMP → NEXT
STEP 10: FREE TEMP
STEP 11: EXIT

DS Deletion in singly linked list after the specified node

C function

#include<stdio.h>
#include<stdlib.h>
void create(int);
void delete_specified();
struct node
{
	int data;
	struct node *next;
};
struct node *head;
void main ()
{
	int choice,item;
	do 
	{
		printf("\n1.Append List\n2.Delete node\n3.Exit\n4.Enter your choice?");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1:
			printf("\nEnter the item\n");
			scanf("%d",&item);
			create(item);
			break; 
			case 2:
			delete_specified();
			break; 
			case 3:
			exit(0);
			break;	
			default:
			printf("\nPlease enter valid choice\n");
		}
				
	}while(choice != 3);
}
void create(int item)
	{
		struct node *ptr = (struct node *)malloc(sizeof(struct node *));
		if(ptr == NULL)
		{
			printf("\nOVERFLOW\n");
		}
		else
		{
			ptr->data = item;
			ptr->next = head;
			head = ptr;
			printf("\nNode inserted\n");
		}
		
	}
void delete_specified()
	{
		struct node *ptr, *ptr1;
		int loc,i; 
		scanf("%d",&loc);
		ptr=head;
		for(i=0;i<loc;i++)
		{
			ptr1 = ptr;		
			ptr = ptr->next;
			
			if(ptr == NULL)
			{
				printf("\nThere are less than %d elements in the list..\n",loc);
				return;
			}
		}
		ptr1 ->next = ptr ->next;
		free(ptr);
		printf("\nDeleted %d node ",loc);
	}

Output

1.Append List
2.Delete node
3.Exit
4.Enter your choice?1

Enter the item
12

Node inserted

1.Append List
2.Delete node
3.Exit
4.Enter your choice?1

Enter the item
23

Node inserted

1.Append List
2.Delete node
3.Exit
4.Enter your choice?2
12

There are less than 12 elements in the list..

1.Append List
2.Delete node
3.Exit
4.Enter your choice?2
1

Deleted 1 node

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