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hauleth.dev
1defmodule Solution do
2 def load(path) do
3 path
4 |> File.stream!()
5 |> Stream.map(&String.to_integer(String.trim(&1)))
6 |> Enum.to_list()
7 end
8
9 def run([], _, _), do: nil
10 def run(_, _, sum) when sum < 0, do: nil
11 def run([a | _], 1, a), do: [a]
12
13 def run([a | rest], n, sum) do
14 case run(rest, n - 1, sum - a) do
15 nil -> run(rest, n, sum)
16 nums when is_list(nums) -> [a | nums]
17 end
18 end
19end
20
21list = Solution.load("./1/input.txt")
22
23list
24|> Solution.run(2, 2020)
25|> Enum.reduce(&*/2)
26|> IO.inspect(label: "task 1")
27
28list
29|> Solution.run(3, 2020)
30|> Enum.reduce(&*/2)
31|> IO.inspect(label: "task 2")
32
33Benchee.run(%{
34 "first solution" => fn ->
35 try do
36 for x <- list, y <- list, z <- list, x + y + z == 2020 do
37 throw(x * y * z)
38 end
39
40 :error
41 catch
42 num -> {:ok, num}
43 end
44 end,
45 "optimized" => fn ->
46 try do
47 for x <- list,
48 rest = 2020 - x,
49 y <- list,
50 y < rest,
51 rest = 2020 - x - y,
52 z <- list,
53 z <= rest,
54 x + y + z == 2020,
55 do: throw(x * y * z)
56
57 :error
58 catch
59 num -> {:ok, num}
60 end
61 end,
62 "mine" => fn ->
63 Solution.run(list, 3, 2020)
64 end
65})