MODULE 4 - ENHANCED DOUBLY LINKED LIST (QUESTION #1)

Hello, can you please show me how to implement a dictionary using the #TODO starter code (def add_first)?

Mod 4 Homework - Enhanced DoublyLinkedList Doubly Linked Lists (DLLs) support O(1) addition and removal from either end, making them a great choice for queutes or deques. A downside of DLLs (and other linked data structures) is that it takes linear time (O(n)) to access nodes in the middle - in a traditional DL., we have to start at the beginning and continually call node._next until we get. to the node we're looking for. Here, we'll enhance a DLL with a dictionary of item: node pairs to give us O(1) access to interior nodes. This will speed up membership testing, node insertion at arbitrary locations, and removal of arbitrary nodes to O(1) This is a common design pattern we'll see with other linked data structures like heaps and graphs. Some downsides of this approach to keep in mind: - Dictionary keys must be unique, so this will only work if node items are unique. - Storing and maintaining the dictionary will not asymptotically worsen our O(1) running times or O(n) memory usage, but it will negatively impact both. Selection View Go Run Terminal Help DoublyLinkedList.py - Visual : is intended for safe code browsing. Trust this window to enable all features. Manage Learn More Figure 1: (a) In a standard DLL, we can only access the head and tail nodes in O(1). (b) By using a dictionary of itemtnode pairs, we can immediately jump to any node, as long as we know which item we are interestod in. 1) Add a dictionary DoublyLinkedList.py provides basic Hode and DonblyLintedList classes that supports typical DLL operations. Modify these methods to beep the nodes dictionary up to date with itam:node pairs as youl add and remove from the DLL 8o you can acsess any node in O(1). 2) Implernent __ contains (item) nodea is a private attribute, and thus should not be called explicilty in your tests. Instead, use -nodes to add a O(1). contains_.. () method to your DL., and test _ containe _ () : >) d11 - DoublyLinkedliet (range (5)) s2> 3 in dll of 0(1), even though. 3 it in the modde True P> 5 in dil y Note the uige of "th* to calt the dunder method _. containg _ () Fase