GATE CSE
First time here? Checkout the FAQ!
x
+1 vote
60 views

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 Junior (717 points)   | 60 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 ?

http://stackoverflow.com/questions/1895769/time-complexity-of-node-deletion-in-singly-and-doubly-linked-lists

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

+3 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 (1.1k points)  
selected by
Top Users Jan 2017
  1. Debashish Deka

    9614 Points

  2. sudsho

    5554 Points

  3. Habibkhan

    4878 Points

  4. Bikram

    4774 Points

  5. Vijay Thakur

    4498 Points

  6. Arjun

    4408 Points

  7. saurabh rai

    4236 Points

  8. Sushant Gokhale

    4112 Points

  9. Kapil

    3830 Points

  10. santhoshdevulapally

    3808 Points

Monthly Topper: Rs. 500 gift card

19,371 questions
24,203 answers
53,828 comments
20,370 users