Question

Given a stack myData: 34,78 (top is 34), what is the output after the following operations?

a. Peek(myData)
b. Push(myData, 2)
c. Push(myData, 15)
d. Pop(myData)
e. Pop(myData) print(IsEmpty(myData))

Answer 1

The stack operations result in Peek returning 34, two Push operations adding 2 and 15, and two Pop operations removing 15 and 2. The final IsEmpty check will confirm that the stack is not empty with a return value of False.

Step-by-step explanation:

The student is working with a data structure known as a stack. A stack is a collection of elements with two principal operations: Push, which adds an element to the collection, and Pop, which removes the most recently added element that was not yet removed. The order in which elements come off a stack gives rise to its alternative name, LIFO (last in, first out).

Initially, the stack myData has 34 at the top and 78 below it. Let's go through the operations step by step:

• Peek(myData): This operation returns the element at the top of the stack without removing it. The output will be 34.
• Push(myData, 2): This operation adds the element 2 on top of the stack. Now the stack is: 2, 34, 78.
• Push(myData, 15): This adds 15 to the top of the stack. Now the stack is: 15, 2, 34, 78.
• Pop(myData): This removes the element at the top of the stack, which is 15. After this operation, the stack has: 2, 34, 78.
• Pop(myData): This removes the next element at the top, which is 2. The stack now has: 34, 78.

Finally, when we call IsEmpty(myData), we're checking if the stack is empty. Since the stack still has elements (34 and 78), the output will be False.