|
| 1 | +ExUnit.start() |
| 2 | + |
| 3 | +defmodule Whales do |
| 4 | + def load_file(path) do |
| 5 | + File.read!(path) |
| 6 | + |> String.split(",", trim: true) |
| 7 | + |> Enum.map(&Integer.parse/1) |
| 8 | + |> Enum.map(&elem(&1, 0)) |
| 9 | + end |
| 10 | + |
| 11 | + def distance_to(a, b), do: abs(a - b) |
| 12 | + |
| 13 | + def find_cheapest_route(positions), |
| 14 | + do: find_cheapest_route(positions, Enum.min(positions), nil) |
| 15 | + |
| 16 | + def find_cheapest_route(positions, target, cheapest) do |
| 17 | + if target == Enum.max(positions) + 1 do |
| 18 | + cheapest |
| 19 | + else |
| 20 | + current = |
| 21 | + if target == Enum.max(positions) + 1 do |
| 22 | + cheapest |
| 23 | + else |
| 24 | + positions |
| 25 | + |> Enum.map(fn position -> distance_to(position, target) end) |
| 26 | + |> Enum.sum() |
| 27 | + end |
| 28 | + |
| 29 | + new_cheapest = |
| 30 | + if current < cheapest do |
| 31 | + current |
| 32 | + else |
| 33 | + cheapest |
| 34 | + end |
| 35 | + |
| 36 | + find_cheapest_route(positions, target + 1, new_cheapest) |
| 37 | + end |
| 38 | + end |
| 39 | + |
| 40 | + @spec first() :: Integer |
| 41 | + def first() do |
| 42 | + positions = load_file("../input.txt") |
| 43 | + find_cheapest_route(positions) |
| 44 | + end |
| 45 | + |
| 46 | + @spec second() :: Integer |
| 47 | + def second() do |
| 48 | + end |
| 49 | +end |
| 50 | + |
| 51 | +defmodule WhalesTest do |
| 52 | + use ExUnit.Case |
| 53 | +end |
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