This document describes how to write a member function called InsertNewItem for a doubly linked list class that takes an item reference as a parameter, inserts it into the proper place in the list without allowing duplicates, and returns true if inserted or false if already present. The class contains public constructor and member functions and private Node and head/tail pointers to implement the doubly linked list.

1. In c++: Assume it is a doubly linked list:
Complete a member function called InsertNewItem which takes an item by reference and inserts
it into the proper place in the list. Duplicates are not allowed. Return true if the item
was inserted; false if the item already is in the list and does not need to be inserted.
Class List { public: List(); List(); ... member functions ... bool InsertNewltem(Item &it);
private: struct Node { Item *pltem; Node *next; Node *prev; } Node *head; Node * tail; }