Question

Give the full implementation of an accessor method that returns the sec- ond item from the top of the stack without actually changing the stack. Write separate solutions for the two different stack versions.

Answer 1

To implement an accessor method that returns the second item from the top of the stack without actually changing the stack, we can decrement the top index in the array-based implementation or traverse the linked list twice in the linked list-based implementation.

Step-by-step explanation:

To implement an accessor method that returns the second item from the top of the stack without actually changing the stack, we need to understand how a stack works.

In the array-based implementation of a stack, the top of the stack refers to the element at the highest index of the array. To access the second item from the top, we can simply decrement the top index by 1 and return the element at that index.

In the linked list-based implementation of a stack, we can traverse the linked list starting from the top node. We move to the next node twice to reach the second node from the top and return the data stored in that node.