String List engine(so no length limit) with its distinguishing feature being that it has item retrieval in O(log(n)) time. Practical application: You have some list that you keep adding to and getting items from but nothing else.
Operation Time Complexity: Get Item: O(logn) Add Item: O(k) Length: O(k) ^ k is the length of the item at the end of the list. Remove Item: O(n) Insert Item: O(n) Replace Item: O(n)