29 lines
1.2 KiB
Elixir
29 lines
1.2 KiB
Elixir
defmodule Day12Part1 do
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def run do
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File.read!("input")
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|> String.split("\n", trim: true)
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|> Enum.map(fn <<action::binary-1>> <> value -> {action, String.to_integer(value)} end)
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|> Enum.reduce({0, 0, {1, 0}}, &process/2)
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|> manhattan_distance()
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|> IO.puts()
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end
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def process({"N", value}, {x, y, direction}), do: {x, y + value, direction}
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def process({"S", value}, {x, y, direction}), do: {x, y - value, direction}
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def process({"E", value}, {x, y, direction}), do: {x + value, y, direction}
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def process({"W", value}, {x, y, direction}), do: {x - value, y, direction}
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def process({"L", value}, {x, y, direction}), do: {x, y, turn_left(direction, value)}
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def process({"R", value}, {x, y, direction}), do: {x, y, turn_right(direction, value)}
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def process({"F", value}, {x, y, {vx, vy}}), do: {x + vx * value, y + vy * value, {vx, vy}}
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def turn_left(direction, 0), do: direction
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def turn_left({vx, vy}, degrees), do: turn_left({-vy, vx}, degrees - 90)
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def turn_right(direction, 0), do: direction
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def turn_right({vx, vy}, degrees), do: turn_right({vy, -vx}, degrees - 90)
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def manhattan_distance({x, y, _}), do: abs(x) + abs(y)
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end
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Day12Part1.run()
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