he Node struct will now have: obj, pointer to the next node, and pointer to the prev node.

Modify the Node struct appropriately $$ already provided for you.

The DoublyLinkedList class will have the same public methods as in LinkedList class except

that we need to add a getLast, and getPrev methods. Further a new data member $$ tail is

added. All the data members need to be maintained while implementing the various operations.

Note that when the list is empty, head, tail and curr will all be nullptrs; when the list is not empty,

head and tail will not be nullptrs and will refer to the first and the last nodes in the list.

These are the additional $$stuff$$ needed to be done $($code for different functions need to be

modified$)$ to take maintain the prev pointers for the nodes in the list, as well as to maintain

head$/$tail$.$

Constructor $$ empty list will have tail set to nullptr $($already done for you$).$

insert $($you need to implement these changes$)$ the old head node should have the prev pointer

set appropriately. Also new head node should have the prev pointer set to nullptr. Further

head$/$tail needs to be updated as needed. What is provided is the insert for the singly linked list

$($as done in class$).$ Check the following $3$ cases which might be significant for your coding: $($a$)$

what happens when you insert a node in an empty list? $($b$)$ What happens when you insert a

node in a list with $1$ node? $($c$)$ what happens when you insert a node in a list with $2$ or more

nodes?

getFirst, getNext, find, retrieve, replace $$ no changes are needed.

getLast, getPrev $$ need to be implemented $$ right now, it just returns false.

remove $$ the code for remove can be much simplified, compared to that of LinkedList. We can

find el using find or retrieve. Because of the prev and next pointers, we can start with where curr

is referring after find$/$retrieve and update the pointers. Check the following cases $($a$)$ what if

the node to be removed is the first node in the list? $($b$)$ what if the node to be removed is the last

node in the list? $($c$)$ what if the node to be removed is the only node in the list? $($d$)$ what if the

node to be removed is in the middle of a list with $3$ or more nodes? Right now the remove code

just returns false.

makeEmpty $$ change is to set tail also to nullptr $($this change is already done for you$).$