Key to CSE341 Section #2 Problems

1. One possible solution appears below.
         fun twoSame([]) = false
         |   twoSame([x]) = false
         |   twoSame(x::y::rest) = (x = y) orelse twoSame(y::rest)

2. One possible solution appears below.
        fun stutter([]) = []
        |   stutter(x::xs) = x::x::stutter(xs);

3. One possible solution appears below.
        fun stutterString(str) = implode(stutter(explode(str)));

4. One possible solution appears below.
        fun isPrime(2) = true
        |   isPrime(n) =
                let fun explore(m) =
                        if m >= n then true
                        else n mod m <> 0 andalso explore(m + 2)
                in n > 2 andalso n mod 2  <> 0 andalso explore(3)
                end;

5. One possible solution appears below.
        fun cycle(0, lst) = lst
        |   cycle(n, lst) = cycle(n - 1, tl(lst) @ [hd(lst)]);

6. One possible solution appears below.
        fun cycle2(n, lst) =
            let fun loop(0, list, back) = list @ List.rev(back)
                |   loop(n, x::xs, back) = loop(n - 1, xs, x::back)
            in loop(n, lst, [])
            end