Why is Selection Sort not stable?

Question

This might be trivial, but I don\'t understand why the default implementation of Selection Sort is not stable?

At each iteration you find the minimum element in the rema

Answer 1

A small example:

Let b = B in

< B > , < b > , < a > , < C > (with a < b < c)

After one cycle the sequence is sorted but the order of B and b has changed:

< a > , < b > , < B > , < c >

But you can however implement Selections Sort stable if you, instead of switching, insert the minimum value. But for that to be efficient you should have a data structure that supports insertion at a low cost or otherwise you end up with quadratic complexity.