Problem 1: Given s={a, b, c}. Print all powersets. {{}, a, b, c, (a, b), (a, c), (b, a)....}
Problem 2: https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/

I didn't do any bit manipulation or anything for the first problem. I just did a nested loop appending each character/ combination. I think I should have mentioned him that the output should be in 2^n but like I said I didn't look at it as a mathematical operation.

Second was easy.

If I was the interviewer, I'd say no hire.