Question

The destructor given for the link-based implementation of the ADT stack calls pop. Although easy to write, this destructor can be inefficient due to repeated method calls. Write another implementation for the destructor that deallocates the linked nodes directly without calling pop.

Answer 1

To write an efficient destructor for a link-based ADT stack, one can loop through the stack nodes directly and deallocate each without calling the pop method, using a while loop and temporary pointers to safely delete each node.

Step-by-step explanation:

The destructor for a link-based implementation of an Abstract Data Type (ADT) stack can indeed be inefficient if it repeatedly calls the pop function. Instead, we can write a more efficient destructor that deallocates the linked nodes directly. Below is an alternative implementation for such a destructor:

~Stack() {
Node* current = top;
while (current != nullptr) {
Node* temp = current;
current = current->next;
delete temp;
}
}
This destructor iterates through each node in the stack, starting from the top. It uses a temporary pointer to hold the current node before moving to the next one. After updating the current pointer to the next node, it safely deletes the node pointed to by the temporary pointer. This process repeats until all nodes have been deleted, at which point the stack is completely deallocated.