72 lines
1.4 KiB
Elixir
72 lines
1.4 KiB
Elixir
defmodule Day8 do
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def part1 do
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File.read!("lib/day8/input.txt")
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|> parse_input()
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|> split_into_layers(25, 6)
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|> min_zeros()
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|> ones_times_twos()
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# "123456789012"
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# |> parse_input()
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# |> split_into_layers(3, 2)
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# |> min_zeros()
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# |> ones_times_twos()
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end
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def part2 do
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File.read!("lib/day8/input.txt")
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|> parse_input()
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|> split_into_layers(25, 6)
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|> combine_layers()
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|> Enum.map(fn
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0 -> ?\s
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1 -> ?X
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end)
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|> Enum.chunk_every(25)
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|> Enum.each(&IO.puts/1)
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# "0222112222120000"
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# |> parse_input()
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# |> split_into_layers(2, 2)
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# |> combine_layers()
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end
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def parse_input(str) do
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str
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|> String.trim()
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|> String.to_charlist()
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|> Enum.map(fn digit -> digit - ?0 end)
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end
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def split_into_layers(input, layer_width, layer_height) do
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Enum.chunk_every(input, layer_width * layer_height)
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end
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def min_zeros(layers) do
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layers
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|> Enum.min_by(fn layer ->
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Enum.count(layer, &(&1 == 0))
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end)
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end
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def ones_times_twos(layer) do
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ones = Enum.count(layer, &(&1 == 1))
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twos = Enum.count(layer, &(&1 == 2))
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ones * twos
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end
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def combine_layers(layers) do
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Enum.zip(layers)
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|> Enum.map(&combine_pixel/1)
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end
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def combine_pixel(pixel) do
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0..(tuple_size(pixel) - 1)
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|> Enum.map(fn index -> elem(pixel, index) end)
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|> Enum.reduce(2, fn
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val, 2 -> val
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_, it -> it
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end)
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end
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end
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