i am not able to do this question.
pls tell the code.
Count subsequences
@yutikakhanna hey ,please try using this approach ,if you still not got it than I will give code for reference .
Generate all the possible subsequences of a given string. The subsequences of a string can be generated in the following manner:
a) Include a particular element(say ith) in the output array and recursively call the function for the rest of the input string. This results in the subsequences of a string having ith character.
b) Exclude a particular element(say ith) and recursively call the function for the rest of the input string. This contains all the subsequences which don’t have the ith character.
Once we have generated a subsequence, in the base case of the function we insert that generated subsequence in an unordered set. Unordered Set is a Data structure, that stores distinct elements in an unordered manner. This way we insert all the generated subsequences in the set and print the size of the set as our answer because at last, the set will contain only distinct subsequences.
Happy coding 
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