DSA-21-7-25

Which of the following correctly represents the algorithm for pushing an element onto a stack using an array?

• if (top == MAX - 1)

  print("Overflow");

  else {

  top++;

  stack[top] = item;

  }

• if (top == -1)

  print("Underflow");

  else {

  top--;

  stack[top] = item;

  }

• top++;

  stack[top] = item;

• top--;

  stack[top] = item;

What condition indicates stack underflow during a pop operation?

• top == MAX

• top == 0

• top == -1

• top > MAX

What is the result of this postfix expression evaluation?
5 3 2 * +

• 16

• 11

• 21

• 13

What is the algorithm for checking if a string has balanced parentheses using a stack?

• • Traverse the string

  • Push opening brackets

  • For each closing bracket, check and pop

  • If stack is empty at the end → balanced

• • Push only closing brackets

  • At end, check if stack size is 2

• • Ignore brackets

  • Count them manually

• Always return true

Which of the following algorithms can be solved using stack?

• Infix to Postfix Conversion

• Expression Evaluation

• Balanced Parentheses

• all the above

The time complexity of push() and pop() in a stack is:

• O(n)

• O(n log n)

• O(1)

• O(log n)

A stack can be implemented using:

• Arrays only

• Linked List only

• Both Arrays and Linked List

• None of the above

If stack is empty and pop() is called, what happens?

• Returns 0

• Underflow occurs

• Overflow occurs

• Returns top element

What is a stack?

• FIFO data structure

• LIFO data structure

• FILO data structure

• Both B and C

What will be the content of the stack after executing the following algorithm?
Initialize an empty stack

Push(10)

Push(20)

Pop()

Push(30)

Push(40)

• Top → 40, 30, 10

• Top → 40, 30, 20

• Top → 30, 40

• Top → 40, 30