First time here? Checkout the FAQ!
+1 vote

The Answer given is A) 

I think the naswer should be B) as we have both the prev pointer and the next pointer available , it will take constant time to update the adjacent nodes pointers and delete the given node .?


asked in DS by Loyal (2.7k points)   | 331 views
In linked list finding element itself takes O(n) time and deletion takes O(1) time,so it is O(n).

suppose if elements stored in DLL are (head)12,5,8,6,9,4,13(tail).

to find an element '9' worst case we need to traverse entire list.

So does deletion include search time as well ? 

I thought that the position of the node is already known and we have to only perform deletion.

So if this question comes in exam what do we consider ?

For deletion=search time+link modification

When deleted node address is given then in CDLL we can perform deletion in O(1) time.

In SLL eventhough deleted node address given it takes O(n) time.

In the given question address is not specified so TC=O(n) otherwise it is O(1) only in CDLL but not DLL.

IN DLL also reaching last node it takes O(n) time in CLL with help of prev pointer at first node we can reach last in O(1)

1 Answer

+4 votes
Best answer

If the pointer to the node to be deleted is given then worst case time complexity would be O(1). But since it is not given, we would have only pointer to the head. So before deleting we would have to search by traversing the LL. In worst case it might take O(n) and deleting would take only O(1). 

Thus O(n).

answered by Active (1.2k points)  
selected by

Top Users Aug 2017
  1. Bikram

    5034 Points


    4730 Points

  3. akash.dinkar12

    3488 Points

  4. manu00x

    3296 Points

  5. rahul sharma 5

    3178 Points

  6. makhdoom ghaya

    2530 Points

  7. just_bhavana

    2428 Points

  8. stblue

    2240 Points

  9. Tesla!

    2076 Points

  10. joshi_nitish

    1830 Points

25,032 questions
32,178 answers
30,218 users