sw/src/pascal/QSORT.PS

   1   PROCEDURE SORT(L,R: INDEX);
   2     VAR I,J: INDEX;  X,H: ITEM;
   3
   4   BEGIN  I := L;  J := R;
   5       X := A[ (L+R) DIV 2 ];
   6       REPEAT
   7           WHILE A[I]<X DO I := I+1;
   8           WHILE X<A[J] DO J := J-1;
   9           IF I<=J THEN
  10           BEGIN  H := A[I];  A[I] := A[J];  A[J] := H;
  11               I := I+1;  J := J-1
  12           END
  13       UNTIL I>J;
  14       IF L<J THEN SORT(L,J);
  15       IF I<R THEN SORT(I,R)
  16   END (* SORT *);