54 lines
1.1 KiB
Elixir
54 lines
1.1 KiB
Elixir
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defmodule AOC.Day8 do
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use AOC.Day, day: 8, debug: true
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def parse_input(lines) do
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Enum.map(lines, fn line ->
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line
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|> String.split("", trim: true)
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|> Enum.map(&String.to_integer/1)
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end)
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end
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def part1(rows) do
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rows = with_index(rows)
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cols = Enum.zip(rows) |> Enum.map(&Tuple.to_list/1)
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rrows = Enum.map(rows, &Enum.reverse/1)
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rcols = Enum.map(cols, &Enum.reverse/1)
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[rows, cols, rrows, rcols]
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|> Enum.map(&count_visible/1)
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|> Enum.reduce(&MapSet.union/2)
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|> Enum.count()
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end
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def part2(rows) do
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rows
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end
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def with_index(rows) do
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Enum.with_index(rows, fn row, y ->
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Enum.with_index(row, fn el, x ->
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%{height: el, x: x, y: y}
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end)
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end)
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end
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def count_visible(rows) do
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rows
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|> Enum.map(&count_visible_row/1)
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|> Enum.map(&elem(&1, 0))
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|> Enum.reduce(&MapSet.union/2)
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end
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def count_visible_row(row) do
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Enum.reduce(row, {MapSet.new(), -1}, fn
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%{height: h, x: x, y: y}, {trees, highest} when h > highest ->
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{MapSet.put(trees, {x, y}), h}
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_, acc ->
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acc
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end)
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end
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end
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