Implement a linked list class that simulates a stack.

Your linked list stack class should have a top pointer that always points to the front element.

Rear is not needed.

Make sure to have struct Node before the class LLStack. For example:

$//$LLStack$.$h

typedef char el$\_$t;

struct Node$\backslash \{$

el$\_$t elem;

N$$de$*$ next;

$\backslash \}$

class LLStack

$\backslash \{$

private:

$//$top pointer

public:

$//$constructor

$//$destructor

$//$isEmpty$()$

$//$push$($el$\_$t$)$

$//$pop$($el$\_$t$\backslash$&$)$

$//$displayAll$()$

$//$underflow

$\backslash \}$;

For some of the following functions, it can be helpful if you draw how they are supposed to work before coding it$.$

Your constructor should make sure that top points to NULL.

Your destructor should go through the entire linked list and delete every node starting from the front. $($hint call pop in a loop$)$

isEmpty should return true or false depending what top points to$.$ Push is going to act similarly to addFront in the notes Notes$11-$Iqueue. It will add a node to the front of the linked list and not return anything. $($Hint: You need to create a new node$)$

Pop is going to act similarly as deleteFront in notes Notes$11-$Iqueue. $($There is no rear here so no need to consider the special case.$)$ Make sure to throw underflow if empty. Pop only returns the element using pass by reference and nothing else will be returned.

displayAll$()$ should output every element inside of the linked list, starting from top, in a vertical line. It will not change anything, nor will it return anything. If there is nothing in the stack make sure to output $"[$ EMPTY$]".$ code that will give you the following output:

Here is what the output should look like:

$```$

$-$ Stack looks like:

$[$ EMPTY $]$

adding a and b to stack

Stack looks like:

b

a

removing top element

Stack looks like:

a

adding c and d to stack

Stack looks like:

d

c

a

calling destructor...

Process exited after $0\mathrm{.}07801$ seconds with return value $0$

Press any key to continue $.$

$```$