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1defmodule Wires do
2 @directions %{
3 ?U => :up,
4 ?D => :down,
5 ?R => :right,
6 ?L => :left
7 }
8
9 @moves %{
10 up: {0, 1},
11 down: {0, -1},
12 right: {1, 0},
13 left: {-1, 0}
14 }
15
16 def load(list) do
17 list
18 |> Enum.map(&parse/1)
19 |> wire()
20 end
21
22 defp parse(<<c, rest::binary>>) do
23 {Map.fetch!(@directions, c), String.to_integer(rest)}
24 end
25
26 defp wire(steps) do
27 steps
28 |> Enum.reduce({[], {0, 0}}, &into_coordinates/2)
29 |> elem(0)
30 |> MapSet.new()
31 end
32
33 defp into_coordinates({_, 0}, {points, curr}), do: {[curr | points], curr}
34 defp into_coordinates({dir, n}, {points, {x, y}}) do
35 {dx, dy} = Map.fetch!(@moves, dir)
36 next = {x + dx, y + dy}
37
38 into_coordinates({dir, n - 1}, {[next | points], next})
39 end
40end
41
42w1 =
43 IO.read(:line)
44 |> String.trim()
45 |> String.split(",")
46 |> Wires.load()
47w2 =
48 IO.read(:line)
49 |> String.trim()
50 |> String.split(",")
51 |> Wires.load()
52
53MapSet.intersection(w1, w2)
54|> MapSet.to_list()
55|> Enum.map(fn {x, y} -> abs(x) + abs(y) end)
56|> Enum.min()
57|> IO.inspect()