| :- dynamic seed/1. |
| |
| /* VAX C-Prolog Benchmark Package */ |
| /* Copyright 1985 by Tektronix, Inc., and Portland State University */ |
| |
| qsort(N) :- |
| generate(0,N,L), !, |
| quicksort(L,S). |
| |
| generate(I,N,[]) :- I = N. |
| generate(I,N,L) :- |
| J is I+1, |
| random(1001,X), |
| generate(J,N,L1), |
| append([X],L1,L). |
| |
| append([],L,L). |
| append([X|L1],L2,[X|L3]) :- append(L1,L2,L3). |
| |
| seed(1301). |
| |
| random(R,N) :- retract(seed(S)), |
| N is (S mod R)+1, |
| NewSeed is (125*S+1) mod 4096, |
| asserta(seed(NewSeed)), !. |
| |
| quicksort([],[]). |
| quicksort([H|T],S) :- split(H,T,A,B), |
| quicksort(A,A1), |
| quicksort(B,B1), |
| append(A1,[H|B1],S). |
| |
| split(H,[A|X],[A|Y],Z) :- A > H, split(H,X,Y,Z). |
| split(H,[A|X],Y,[A|Z]) :- A < H, split(H,X,Y,Z). |
| split(_,[],[],[]). |
| |
