Data Structures Data Structures 2

Question 1

What is the worst-case time complexity of searching for an element in a balanced binary search tree with n nodes?

Accepted Answer

O(log n)

Answer

A balanced BST halves the search space at each level, giving O(log n) worst-case search time.

Question 2

Which data structure uses the Last-In-First-Out (LIFO) principle?

Accepted Answer

Stack

Answer

A stack only allows insertion and removal at the top, so the last element pushed is the first popped.

Question 3

In a singly linked list, what does the last node's next pointer typically reference?

Accepted Answer

Null

Answer

In a standard singly linked list, the tail node's next pointer is null to mark the end of the list.

Question 4

Which of the following operations is most efficient on an array compared to a linked list?

Accepted Answer

Random access by index

Answer

Arrays store elements contiguously, allowing O(1) access by index, while linked lists require O(n) traversal.

Question 5

What happens when two keys hash to the same index in a hash table using chaining?

Accepted Answer

Both entries are stored in a linked list at that index

Answer

Chaining resolves collisions by storing multiple entries in a list (or similar structure) at the same bucket.

Data Structures Practice Test