HOMEWORK 5.

Deadline: Monday, November 15.

1. Given a list of elements colored red, white, and blue, reorder 
the list so that all the red elements appear first, then all the
white elements, followed by the blue elements. The reordering should
prserve the original relative order of elements of the same color.
Sample run:

?- reorder([red(1), white(2), blue(3), red(4), white(5)], Reordered].

Reordered = [red(1), red(4), white(2), white(5), blue(3)];

no

Write two versions of the reordering program: with and without difference
lists.



2. Implement two versions of the quicksort algorithm: with and without 
difference lists.