Basics

Question 1

What is the difference between an array and a linked list?

Answer 1

Arrays allow random access (O(1)) but have fixed sizes; linked lists allow dynamic memory allocation but require sequential access (O(n)).

Question 2

What is the time complexity of accessing an element in an array?

Answer 2

O(1) (constant time).

Question 3

What is the time complexity of accessing an element in a linked list?

Answer 3

O(n) (linear time).

Question 4

What are the advantages of a doubly linked list over a singly linked list?

Answer 4

Doubly linked lists allow backward traversal and easier deletion but use extra memory.

Question 5

What is a stack? What are its key operations?

Answer 5

LIFO (Last In, First Out), operations: push(), pop(), peek().

Question 6

What is a queue? How does it differ from a stack?

Answer 6

FIFO (First In, First Out), operations: enqueue(), dequeue().

Question 7

How does a priority queue work?

Answer 7

Elements are dequeued in order of priority rather than order of insertion.

Question 8

What is the difference between a min-heap and a max-heap?

Answer 8

Min-Heap: smallest element at root; Max-Heap: largest element at root.

Question 9

What are hash tables used for?

Answer 9

Store key-value pairs for fast lookups (O(1) on average).

Question 10

What are common collision resolution techniques for hash tables?

Answer 10

Chaining, Open Addressing (Linear Probing, Quadratic Probing, Double Hashing).