A lot of the focus in the HN comments is on ArrayLists, but I'm curious why the author chose to give linked lists an O(1) insert time. In some implementations (doubly linked list, inserting at the head of the list) I can see the O(1) time, but when appending to the end it also is O(n) because one has to traverse the entire list of elements before updating the link at the end of the list. Might just be nitpicking here but that might also be affecting the author's results.