What I understood is author wanted “Good Subsequence” to be calculated and not Subsequence of an array.
After reading Problem statement again and again what I realise that goodsubsequence can only be derived from good sequence.
Good sequence=“She defines a good sequence of integers as a non-empty sequence such that the sum of the elements in each of its non-empty subsequences is divisible by m”.
In order to form a good sequence straight away remove elements from array not divisible by m.
For an array or String subsequence/Subset:-
(2^n-1). //-1 for removing null set
^ --> raise to
n–> No. of elements in array
Am I right?