UGC-NET Computer Science Data Structures Questions with Explanation

In this Blog we are providing all the UGC-NET Computer Science previous year Questions with explanation:

Q:3 Given an empty stack, after performing push(1), push(2), Pop, push(3), push(4), Pop, Pop, push(5),Pop, what is the value of the top of the stack?

(A) 4
(B) 3
(C) 2
(D) 1

(UGC-NET Computer Science December 2012)

Answer: (D)

Explanation:

An empty stack will look like this:

After performing Push(1):

1

1 will be on TOP.

After performing Push(2):

2
1

2 will be on TOP.

After performing POP:

1

Again 1 will be on TOP.

After performing Push(3), Push(4):

4
3
1

After performing POP, POP:

1

1 will be on TOP.

After performing Push(5), POP again 1 will be on TOP of the Stack. Hence option (D) is Correct.

This question was taken from UGC-NET Computer Science December 2012.