Puzzle - RPL and others

[C.Ret]

Here a version for HP-28C/S RPL Advanced Scientific Calculator;
As previous proposed code, it is based on a recursive approach, using the stack to store intermediate data.

Code:

NTST:
« IF DUP SIZE 9 < THEN 49 57 FOR c DUP c CHR
                               IF DUP2 POS THEN DROP2
                                           ELSE IF + DUP STR→ OVER SIZE MOD THEN DROP
                                                                            ELSE NTST END END
                             NEXT
                  ELSE DUP DEPTH ROLLD END
  DROP  »

Usage:
Initiate the research by entering an empty string :
"" NTST
will return the solution in level 1: of the stack. Meanwhile, this code also verify that no other solution exists.

One may spare running time by indicating a starting sequence such as "381" NST and the code will search for solution only starting with 381... eventually a solution may be found or the program ends leaving the stack unchanged.

EDIT: On my HP-28S founding the solution starting with the empty string "" and scanning over all possibilities takes about 2'54". A shorter time may be reach (aka 1'22") by KILLing the process as soon as the unique solution is found. (by replacing DUP DEPTH ROLLD sequence by a KILL)

EDIT #2:
translating this RPL code into HP-71B's BASIC, I get a five liner of 158 octets:

Code:

10 DESTROY ALL @ CALL NTST("") @ END

20 SUB NTST(N$) @ IF LEN(N$)=9 THEN BEEP @ DISP(N$) @ END ALL
22 FOR C=49 TO 57 @ X$=CHR$(C) @ IF POS(N$,X$) THEN 26 ELSE X$=N$&X$
24 IF MOD(VAL(X$),LEN(X$)) THEN 26 ELSE CALL NTST(X$)
26 NEXT C @ END SUB

On my HP-71B, the solution is found in 1'12"