GATE CS 2023 Set 1 — Question 13
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Programming & Data Structures → Linked Lists → Doubly Linked Lists
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Question
Let
Let denote the number of nodes in each of the linked lists. Which one of the following choices is TRUE about the worst-case time complexity of
SLLdel be a function that deletes a node in a singly-linked list given a pointer to the node and a pointer to the head of the list. Similarly, let DLLdel be another function that deletes a node in a doubly-linked list given a pointer to the node and a pointer to the head of the list.Let denote the number of nodes in each of the linked lists. Which one of the following choices is TRUE about the worst-case time complexity of
SLLdel and DLLdel?Correct answer
(D) SLLdel is O(n) and DLLdel is O(1)
Solution
In a singly linked list, to delete a node given its pointer, we must update the
next pointer of its predecessor. Since we only have a pointer to the node itself and the head, we must traverse the list from the head to find the predecessor, which takes time in the worst case. In a doubly linked list, each node contains a pointer to its predecessor (prev), allowing us to update the links in time without traversal.Continue learning with Success Tracker
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