Data Structures Linked Lists

Question 1

What is the time complexity of inserting a node at the beginning of a singly linked list?

Accepted Answer

O(1)

Answer

O(n)

Answer

O(log n)

Answer

O(n²)

Question 2

Which algorithm detects a cycle in a linked list using O(1) extra space?

Accepted Answer

Floyd's cycle detection (slow/fast pointers)

Answer

DFS traversal

Answer

Hash set tracking

Answer

Reverse and compare

Question 3

What is the main disadvantage of singly linked lists compared to arrays?

Accepted Answer

No random access by index

Answer

Higher insertion cost at head

Answer

Requires more CPU operations for sorting

Answer

Cannot store duplicate values

Question 4

How do you find the middle node of a linked list in one pass?

Accepted Answer

Use two pointers where fast moves twice as fast as slow

Answer

Count nodes then traverse to n/2

Answer

Store all nodes in an array

Answer

Traverse from both ends simultaneously

Question 5

What is the time complexity of deleting a node from a singly linked list given only a pointer to that node (not the previous)?

Accepted Answer

O(1) by copying successor data

Answer

O(n) to find the predecessor

Answer

O(log n)

Answer

Impossible without the previous node

Question 6

Which linked list variant allows traversal in both forward and backward directions?

Accepted Answer

Doubly linked list

Answer

Circular linked list

Answer

Skip list

Answer

XOR linked list