% sorting algorithm (quick sort)
qsort([],[]).
qsort([0],[0]).
qsort([1],[1]).
qsort([2],[2]).
qsort([0,1],[0,1]).
qsort([1,0],[0,1]).
qsort([0,2],[0,2]).
qsort([2,0],[0,2]).
qsort([1,2],[1,2]).
qsort([2,1],[1,2]).
qsort([0,1,2],[0,1,2]).
qsort([0,2,1],[0,1,2]).
qsort([1,0,2],[0,1,2]).
qsort([1,2,0],[0,1,2]).
qsort([2,0,1],[0,1,2]).
qsort([2,1,0],[0,1,2]).