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; \}