DIM T(9)
CALL backtrack(T,1)
END

EXTERNAL SUB backtrack(T(),p)
FOR i=1 TO 9
   FOR k=1 TO p-1                  ! 同じ数字かどうか
      IF T(k)=i THEN EXIT FOR
   NEXT k
   IF k>p-1 THEN
      LET T(p)=i
      IF p=9 THEN                  ! すべての数が埋まったら
         FOR s=1 TO 9
            PRINT T(s);
         NEXT s
         PRINT
      ELSE
         CALL backtrack(T,p+1)     ! 再帰
      END IF
   END IF
NEXT i
END SUB