Stack

Process of inserting an element in stack is called ____________

• Create

• Push

• Evaluation

• Pop

Answer explanation

Push operation allows users to insert elements in the stack.

Process of removing an element from stack is called __________

• Create

• Push

• Evaluation

• Pop

Answer explanation

Elements in the stack are removed using pop operation. Pop operation removes the top most element in the stack i.e. last entered element.

In a stack, if a user tries to remove an element from an empty stack it is called _________

• Underflow

• Empty collection

• Overflow

• Garbage Collection

Answer explanation

Underflow occurs when the user performs a pop operation on an empty stack. Overflow occurs when the stack is full and the user performs a push operation. Garbage Collection is used to recover the memory occupied by objects that are no longer used.

Pushing an element into stack already having five elements and stack size of 5, then stack becomes ___________________

• Overflow

• Crash

• Underflow

• User flow

Answer explanation

The stack is filled with 5 elements and pushing one more element causes a stack overflow. This results in overwriting memory, code and loss of unsaved work on the computer.

Which of the following is not the application of stack?

• A parentheses balancing program

• Tracking of local variables at run time

• Compiler Syntax Analyzer

• Data Transfer between two asynchronous process

Answer explanation

Data transfer between the two asynchronous process uses the queue data structure for synchronisation. The rest are all stack applications.

Consider the usual algorithm for determining whether a sequence of parentheses is balanced. The maximum number of parentheses that appear on the stack AT ANY ONE TIME when the algorithm analyzes: (()(())(())) ?

• 1

• 2

• 3

• 4 or more

Answer explanation

In the entire parenthesis balancing method when the incoming token is a left parenthesis it is pushed into stack. A right parenthesis makes pop operation to delete the elements in stack till we get left parenthesis as top most element. 2 left parenthesis are pushed whereas one right parenthesis removes one of left parenthesis. 2 elements are there before right parenthesis which is the maximum number of elements in stack at run time.

What is the value of the postfix expression 6 3 2 4 + – *?

• 1

• 40

• 74

• -18

Here is an infix expression: 4 + 3*(6*3-12). Suppose that we are using the usual stack algorithm to convert the expression from infix to postfix notation. The maximum number of symbols that will appear on the stack AT ONE TIME during the conversion of this expression?

• 1

• 2

• 3

• 4

What is the result of the following operation?
Top (Push (S, X))

• X

• X+S

• S

• XS

Which of the following statement(s) about stack data structure is/are NOT correct?

• Linked List are used for implementing Stacks

• Top of the Stack always contain the new node

• Stack is the FIFO data structure

• Null link is present in the last node at the bottom of the stack