Question

Statement 1: Shell sort is a stable sorting algorithm.

Statement 2: Shell sort is an in-place sorting algorithm.

(a) Both statements are true

(b) Statement 2 is true but statement 1 is false

(c) Statement 2 is false but statement 1 is true

(d) Both statements are false

The question was posed to me in unit test.

This is a very interesting question from Shell sort in portion Sorting of Data Structures & Algorithms II

Answer 1

The correct option is (b) Statement 2 is true but statement 1 is false

The best explanation: In Shell sort, the relative order of elements with equal values may change. Therefore, it is not a stable sorting algorithm. Shell sort is an in-place sorting algorithm as it requires O(1) auxiliary space.