Question

Which of the following is not a variant of merge sort?

(a) in-place merge sort

(b) bottom up merge sort

(c) top down merge sort

(d) linear merge sort

This question was addressed to me in an interview for job.

This intriguing question originated from Sorting topic in section Sorting of Data Structures & Algorithms II

Answer 1

Correct choice is (d) linear merge sort

The best I can explain: In-place, top down and bottom up merge sort are different variants of merge sort. Whereas linear merge sort is not a possible variant as it is a comparison based sort and the minimum time complexity of any comparison based sort is O(n log n).