03/07/2025
In this project, you will implement a sentineled doubly-linked list. Recall that a linked list is composed of Node objects that are linked together. This means that we will need to create two classes in this implementation. One class will represent the Nodes of data and how they are linked together. The other class will represent the actual Linked List, defining methods for adding and removing elements, creating a string representation of the object, and obtaining its length.
We have discussed a variety of methods for inserting and removing values in a linked list. This project will use index-based addressing. Recall from our studies of arrays that index zero identifies the location of the first datum. This approach also means that the maximum valid index is one less than the length of the sequence. We will replicate that indexing paradigm here. Note that index zero identifies the first Node object that contains data, and not the header. Neither the header nor the trailer has an index.
Your implementation should support the following methods, keeping in mind that the words index, head, and tail are used descriptively only and should not appear as attributes of either class. For methods that take indices as parameters, you should start at the sentinel node closest to the provided index when moving the required location in the list.
append_element(self, val) This method should increase the size of the list by one, adding the specified value in the new tail position. This is the only way to add a value as the tail.
insert_element_at(self, val, index) If the provided index identifies a valid zero-based position within the list, then insert the specified value at that position, increasing the length by one. This method can be used to insert at the head of a non-empty list, but cannot append to a list. The provided index must be within the current bounds of the list. If the index is not valid, raise an IndexError exception.
In this project, you will implement a sentineled doubly-linked list. Recall that a linked list is composed of Node objects that are linked together. This means that we will need to create two classes in this implementation. One class will represent the Nodes of data and how they are linked together....
