问题
I want to implement a modification to merge sort, where n/k sublists of length k are sorted using insertion sort and then merged using the standard merging mechanism of merg sort. I'm wondering what the value k has to equal for the modified version of merge sort to equal the original version of merge sort in terms of rum time complexity. This is a conceptual exercise by myself for myself. Code and or an explanation is appreciated.
回答1:
Your n/k-way merge is O(n^2/k) (explanation here). Each of your individual insertion sorts are O(k^2). Observe that for any value of k, your overall running complexity will remain O(n^2); therefore, no value of k will allow your modified merge sort to be O(nlogn)
来源：https://stackoverflow.com/questions/19533057/modification-to-merge-sort-to-implement-merge-sort-with-insertion-sort-java