@all above you are suggesting brute force solution and have a look at the
constraints and time limits which are too strict so such solution would
work over here i need a DP approach.
@vandana we can't make hash because of the high value of N.
@ramindar actually not only reverse there exist all
@atul as the problem said i have to find Nth PDS number so N could be 10^9
so 9 digits and pds number can be of 10digits so scanning from 1 to 10^10
in each case (because we can make such a large hash) will cross time limits
as there would be 1 test cases so it become 10^14 and which can't
