-module(min_avg_two_slice).
-export([min_avg_two_slice/1]).

min_avg_two_slice(A) ->
    N = length(A),
    Arr = array:from_list(A),
    Init = (array:get(0, Arr) + array:get(1, Arr)) / 2,
    {_, Idx} = lists:foldl(fun(I, {MinV, IdxAcc}) ->
        Two = (array:get(I, Arr) + array:get(I + 1, Arr)) / 2,
        Cur = case I + 2 < N of
            true ->
                Three = (array:get(I, Arr) + array:get(I + 1, Arr) + array:get(I + 2, Arr)) / 3,
                min(Two, Three);
            false ->
                Two
        end,
        case Cur < MinV of
            true -> {Cur, I};
            false -> {MinV, IdxAcc}
        end
    end, {Init, 0}, lists:seq(0, N - 2)),
    Idx.