PROGRAM ACKERMAN

!
! computes Ackermann function
! (second version for rosettacode.org)
!

!$INTEGER

DIM STACK[10000]

!$INCLUDE="PC.LIB"

PROCEDURE ACK(M,N->N)
  LOOP
    CURSOR_SAVE(->CURX%,CURY%)
    LOCATE(8,1)
    PRINT("Livello Stack:";S;"  ")
    LOCATE(CURY%,CURX%)
    IF M<>0 THEN
       IF N<>0 THEN
           STACK[S]=M
           S+=1
           N-=1
        ELSE
           M-=1
           N+=1
        END IF
        CONTINUE LOOP
     ELSE
        N+=1
        S-=1
    END IF
    IF S<>0 THEN
        M=STACK[S]
        M-=1
        CONTINUE LOOP
      ELSE
        EXIT PROCEDURE
    END IF
  END LOOP
END PROCEDURE

BEGIN
   PRINT(CHR$(12);)
   FOR X=0 TO 3 DO
     FOR Y=0 TO 9 DO
        S=1
        ACK(X,Y->ANS)
        PRINT(ANS;)
     END FOR
     PRINT
   END FOR
END PROGRAM