It looks correct to me, but keep in mind that deleting elements from the middle of an array is O(n), so overall your algorithm is O(n^2). You could fix this by

It looks correct to me, but keep in mind that deleting elements from the middle of an array is O(n), so overall your algorithm is O(n^2). You could fix this by always swapping your chosen element with the last element of the sorted_deck before removing it because removing from the end of an array is O(1).