# Stack

 Question 1
Consider the following sequence of operations on an empty stack.

push(54); push(52); pop(); push(55); push(62); s=pop();

Consider the following sequence of operations on an empty queue.

enqueue(21); enqueue(24); dequeue(); enqueue(28); enqueue(32); q=dequeue();

The value of s+q is ___________.
 A 94 B 83 C 79 D 86
GATE CSE 2021 SET-1   Data Structure
Question 1 Explanation:
 Question 2
A stack is implemented with an array of ${ }^{\prime} A[0 \ldots N-1]^{\prime}$ and a variable $\text { 'pos'. }$ The push and pop operations are defined by the following code.
 push (x)
A[pos] <- x
pos <- pos -1
end push
pop()
pos <- pos+1
return A[pos]
end pop

Which of the following will initialize an empty stack with capacity N for the above implementation?
 A $\text { pos } \leftarrow-1$ B $\text { pos } \leftarrow 0$ C $\text { pos } \leftarrow 1$ D $\text { pos } \leftarrow N-1$
ISRO CSE 2020   Data Structure
Question 2 Explanation:

 Question 3
Convert the pre-fix expression to in-fix $-^{*}+A B C^{*}-D E+F G$
 A $(A-B)^{*} C+\left(D^{*} E\right)-(F+G)$ B $(A+B)^{*} C-(D-E)^{*}(F-G)$ C $(A+B-C)^{*}(D-E)^{*}(F+G)$ D $(((A+B)*C)-((D-E)*(F+G)))$
ISRO CSE 2020   Data Structure
Question 3 Explanation:
Originally all Options are wrong. We have modified one option.
 Question 4
Choose the equivalent prefix form of the following expression
$(a+(b-c))^{\star}((d-e) /(f+g-h))$
 A ${ }^{\star}+a-b c /-d e-+f g h$ B ${ }^{\star}+a-b c -/d e-+f g h$ C ${ }^{\star}+a-b c /-ed-+f g h$ D ${ }^{*}+\mathrm{ab}-\mathrm{c} /-\mathrm{de}-+\mathrm{fgh}$
ISRO CSE 2017   Data Structure
Question 4 Explanation:
 Question 5
The best data structure to check whether an arithmetic expression has balanced parenthesis is a:
 A Queue B Stack C Tree D List
ISRO CSE 2017   Data Structure
Question 5 Explanation:

There are 5 questions to complete.