What is the worst case time complexity of inserting n elements into an empty linked list, if the linked list needs to be maintained in sorted order?

$$N$$ items are stored in a sorted doubly linked list. For a $$delete$$ operation, a pointer is provided to the record to be deleted. For a $$decrease$$-$$key$$ operation, a pointer is provided to the record on which the operation is to be performed.

An algorithm performs the following operations on the list in this order:
$$\Theta \left( N \right),\,\,delete,\,\,O\left( {\log N} \right)\,insert,\,$$ $$\,O\left( {\log N} \right)\,fund, and $$ $$\Theta \left( N \right)\,$$ $$decrease$$-$$key.$$ What is the time complexity of all these operations put together?

Let P be a singly linked list, Let Q be the pointer to an intermediate node x in the list.What is the worst-case time complexity of the best known algorithm to delete the node x from the list?

In the worst case, the number of comparisons needed to search a singly linked list of length n for a given element is