Subset Problem Hint Video: How recursion reduces the time complexity?

#1

At 00:52,Ma’am said if we find all the subsets iteratively and find their sum it will take O(n^2).
And then she said that is not a efficient approach so we will use recursion.

But how recursion is effective? Instead if we use recursion, the time complexity now becomes O(2^n). Please correct me if I am wrong.

#2

Someone please help me with this ^^"

#3

@ayushjain.aj300 hey ayush the reason for saying by mam is that
time complexity is exponential. The problem is in-fact NP-Complete(There is no known polynomial time solution for this problem)

#4

Thanks Sir. It helped.