Computer Fundamentals for Placements – DSA MCQs with Answers

Q. 1 Which data structure uses LIFO (Last In First Out) principle?

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Ans: B

A stack follows the LIFO principle where the last inserted element is the first to be removed.

Q. 2 Which of the following has the worst-case time complexity of O(n log n) for sorting?

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Ans: C

Heap Sort has a guaranteed worst-case complexity of O(n log n).

Q. 3 Which data structure is best suited for implementing recursion?

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Ans: B

Recursion uses the call stack to keep track of function calls.

Q. 4 What is the time complexity of searching in a balanced Binary Search Tree (BST)?

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Ans: B

Searching in a balanced BST takes O(log n) time.

Q. 5 Which data structure is used for breadth-first search (BFS) in a graph?

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Ans: B

BFS uses a queue to explore nodes level by level.

Q. 6 What is the best case time complexity of Insertion Sort?

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Ans: A

In the best case (when the array is already sorted), Insertion Sort runs in O(n).

Q. 7 Which traversal method of a binary tree visits nodes in the order: Left, Root, Right?

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Ans: B

Inorder traversal visits Left subtree, then Root, then Right subtree.

Q. 8 Which data structure is typically used to implement priority queues?

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Ans: B

Heaps are commonly used to implement priority queues.

Q. 9 In hashing, what is the technique used to resolve collisions by finding the next empty slot?

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Ans: B

Open Addressing resolves collisions by searching for the next empty slot.

Q. 10 Which graph representation is more space-efficient for sparse graphs?

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Ans: B

Adjacency List is more space-efficient for sparse graphs, as it stores only existing edges.

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