Решение задачи иначе (другим алгоритмом)?

REM 56511 => 61155
 
DECLARE FUNCTION f! (x!, y!)
CLS
 
CONST p = " "
CONST A = 56511
 
FOR i = A + 9 TO 65511 STEP 9
   IF f(A, i) THEN PRINT i: EXIT FOR
NEXT
END
 
FUNCTION f (x, y)
   DIM x1 AS STRING
   DIM y1 AS STRING
   DIM s1 AS STRING
 
   
   x1 = LTRIM$(STR$(x))
   y1 = LTRIM$(STR$(y))
 
   FOR i = 1 TO LEN(x1)
      s1 = MID$(x1, i, 1)
      k = INSTR(y1, s1)
 
      IF k THEN
         MID$(y1, k, 1) = p
      ELSE
         EXIT FUNCTION
      END IF
   NEXT
 
   f = -1
END FUNCTION

DECLARE FUNCTION NextPerm% (a() AS INTEGER, n AS INTEGER)
CONST m = 5
DIM a(1 TO m) AS INTEGER, i AS INTEGER, j AS INTEGER
FOR i = 1 TO m
    READ a(i)
    PRINT a(i);
NEXT i
PRINT
j = NextPerm(a(), m)
FOR i = 1 TO m
    PRINT a(i);
NEXT i
PRINT
DATA 5, 6, 5, 1, 1
 
FUNCTION NextPerm% (a() AS INTEGER, n AS INTEGER)
    DIM i AS INTEGER, k AS INTEGER, t AS INTEGER
    FOR k = n - 1 TO 1 STEP -1
        IF a(k) < a(k + 1) THEN EXIT FOR
    NEXT k
    IF k THEN
        FOR i = n TO k + 1 STEP -1
            IF a(k) < a(i) THEN SWAP a(k), a(i): EXIT FOR
        NEXT i
    END IF
    t = n
    FOR i = k + 1 TO (n + k) \ 2
        SWAP a(i), a(t)
        t = t - 1
    NEXT i
    NextPerm = k
END FUNCTION