This problem can be solved using greedy technic.
Method is to divide the given number from 9 to 2. Each time we will continue to divide and update the number as we go. We will keep dividing N with the same number utill its impossible to do so.And for each division we will save the number which was divisible by given number. And by "save" i mean pushing the number in a stack or a in a vector or an array. If you are using other than stack you might print out the numbers in a reverse manner.

And when we are getting "-1"?
I already wrote that, we keep updating the number. so after we pass the 9 to 2 loop, we should be left with a value of 1 in the variable N ( given number ). Incase N!=1 we are just printing "-1".

For the case N=1 or N=0? for the case 1 you should just print "1" and for the case 0 print "10", we can not print 01 since this refers to number, 1.

If you have problem understanding what i have just written or for better understanding, give this a go : https://ideone.com/709cog

Edited by author 21.02.2020 00:34

Edited by author 21.02.2020 00:38

Edited by author 21.02.2020 00:41