58 lines
1.7 KiB
Elixir
58 lines
1.7 KiB
Elixir
defmodule Coord do
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defstruct [:x, :y]
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end
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defmodule Claim do
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defstruct id: nil, pos: %Coord{x: 0, y: 0}, len: %Coord{x: 0, y: 0}
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@input_pattern ~r/#(\d+) @ (\d+),(\d+): (\d+)x(\d+)/
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def new_from_str(str) do
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[id, pos_x, pos_y, len_x, len_y] =
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Regex.run(@input_pattern, str, capture: :all_but_first)
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|> Enum.map(&String.to_integer/1)
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%Claim{id: id, pos: %Coord{x: pos_x, y: pos_y}, len: %Coord{x: len_x, y: len_y}}
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end
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def all_coords(claim) do
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x_coords = claim.pos.x..(claim.pos.x + claim.len.x - 1)
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y_coords = claim.pos.y..(claim.pos.y + claim.len.y - 1)
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for x <- x_coords, y <- y_coords, do: %Coord{x: x, y: y}
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end
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def unshared?(claim, unshared_inches) do
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Enum.all?(all_coords(claim), &MapSet.member?(unshared_inches, &1))
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end
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end
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defmodule Day3 do
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def count_claim_inches(claim, count) do
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Enum.reduce(Claim.all_coords(claim), count, fn coord, count ->
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Map.update(count, coord, 1, &(&1 + 1))
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end)
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end
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def part1 do
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File.stream!("input")
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|> Stream.map(&Claim.new_from_str/1)
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|> Enum.reduce(%{}, &count_claim_inches/2)
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|> Stream.filter(fn {_coord, count} -> count >= 2 end)
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|> Enum.count()
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end
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def part2 do
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all_claims = File.stream!("input") |> Enum.map(&Claim.new_from_str/1)
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unshared_inches =
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all_claims
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|> Enum.reduce(%{}, &count_claim_inches/2)
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|> Enum.filter(fn {_coord, count} -> count == 1 end)
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|> MapSet.new(fn {coord, _count} -> coord end)
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Enum.find(all_claims, &Claim.unshared?(&1, unshared_inches))
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end
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end
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IO.puts("Part1 (number of square inches claimed multiple times): #{Day3.part1()}")
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IO.puts("Part2 (id of only claim not overlapping with another): #{Day3.part2().id}")
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