Inserting a new node after a given node in a doubly linked list involves changing a few pointers, which takes constant time, hence O(1).

A stack follows the LIFO principle, meaning the last element added is the first one to be removed.

Inserting an element into a hash table typically takes constant time on average, so the average time complexity is O(1).

Deleting the last element from a dynamic array is a constant time operation, so the time complexity is O(1).

Traversing a binary tree requires visiting each node once, leading to a time complexity of O(n).