What is the optimal complexity we can achieve when removing duplicates from an unsorted linked list?*2 pointsO(n)O(n^2)O(n x log(n))None of the above

To determine the optimal complexity for removing duplicates from an unsorted linked list, we need to consider the different approaches and their corresponding time complexities.

One possible approach is to use a hash set to keep track of the unique elements in the linked list. We can iterate through the linked list, and for each element, check if it already exists in the hash set. If it does, we remove the element from the linked list. This approach has a time complexity of O(n), where n is the number of elements in the linked list.

Another approach is to sort the linked list first and then remove duplicates. Sorting the linked list can be done using algorithms like merge sort or quicksort, which have a time complexity of O(n x log(n)). Once the linked list is sorted, we can iterate through it and remove any duplicate elements. This additional iteration has a time complexity of O(n). Therefore, the overall time complexity for this approach is O(n x log(n)).

Based on these approaches, the optimal complexity we can achieve when removing duplicates from an unsorted linked list is O(n), as it is the most efficient approach. Therefore, the correct answer is O(n).