here is my code
defmodule Task1aSumOfSubsets do
@spec valid_sum(maybe_improper_list) :: list
def valid_sum([]), do: []
def valid_sum(list) when is_list(list) do
Enum.filter(list, fn element -> is_integer(element) and element > 0 end)
end
def sum_of_one(list, provided_integer_sum, list_sanitizer \\ &valid_sum/1)
def sum_of_one([], _, _), do: []
def sum_of_one(list, provided_integer_sum, list_sanitizer) do
sanitized_list = list_sanitizer.(list)
combinations = _combinations(sanitized_list)
Enum.filter(
combinations,
fn e -> List.flatten(e) |> Enum.sum() == provided_integer_sum end
)
end
defp _combinations(list) do
List.foldl(
Enum.to_list(1..length(list)),
[],
fn length, acc -> acc ++ _combinations(list, length) end
)
end
defp _combinations(list, 1), do: for(e <- list, do: [e])
defp _combinations(list, length) when length(list) == length, do: [list]
defp _combinations([h | t], length) do
for(sub_sum <- _combinations(t, length - 1), do: [h | sub_sum]) ++ _combinations(t, length)
end
def sum_of_all(list, matrix_2d, list_sanitizer \\ &valid_sum/1) do
calculated_integer_sum = list_sanitizer.(matrix_2d) |> Enum.sum()
sum_of_one(list, calculated_integer_sum)
end
end
