Question

I have been stuck on problem set 6, problem #4, about the even faster computer player, how do I write code to create each subset S of the letters of HAND, e.g. if the letters are [a, b, c, d], there are 11 combinations like ab, ac, ad, bc, bd, cd, abc, abd, acd, bcd, abcd? How do I iterate to create these subsets?

Answer 1

4 letters make 16 combinations(2 to the 4th power), 1 of them empty.
Iterate from 0000 to 1111 in binary numbers on this 4 letters case, each digital shows whether the corresponding letter is in the combination.
i.e: .word = ‘a’ * 1 + 'b' * 0 + 'c' * 1 + 'd' * 1
word = 'acd'
But I think recursive way might be better. subsets of (a, b, c, d) consist of subsets of (a, b, c) and all their combinations with (d,).