Day 17: No Such Thing as Too Much

Section

defmodule P1 do
  def combinations([]), do: [[]]

  def combinations([h | t]) do
    tcs = combinations(t)
    tcs ++ Enum.map(tcs, fn comb -> [h | comb] end)
  end
end

[33, 14, 18, 20, 45, 35, 16, 35, 1, 13, 18, 13, 50, 44, 48, 6, 24, 41, 30, 42]
|> P1.combinations()
|> Enum.filter(fn comb -> Enum.sum(comb) == 150 end)
|> length()

1304

combs =
  [33, 14, 18, 20, 45, 35, 16, 35, 1, 13, 18, 13, 50, 44, 48, 6, 24, 41, 30, 42]
  |> P1.combinations()
  |> Enum.filter(fn comb -> Enum.sum(comb) == 150 end)

min_len =
  combs
  |> Enum.map(&length/1)
  |> Enum.min()

combs
|> Enum.filter(fn comb -> length(comb) == min_len end)
|> Enum.count()

18