Java实现中已排序和未排序链接列表的合并

Question

I was reading about sorted linked lists and unsorted sorted lists ... I found this table http://bigocheatsheet.com/

I do not understand what they mean by saying in the third table that a sorted linked list has Merge of O(m+n) while an unsorted sorted list has Merge of O(1) !

What does that mean?

thanks

Answer 1

It's saying that the optimal time to merge a sorted list is O(m + n), because you have to traverse both lists, compare the top/bottom and decide which is higher / lower. Unsorted list could in theory be merged in O(1) if this is a linked list... you just point the tail of the first linked list to the second linked list