87 lines
2.2 KiB
Elixir
87 lines
2.2 KiB
Elixir
defmodule DayThree do
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def parse_claim(claim) do
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pattern = ~r/#(\d+) @ (\d+),(\d+): (\d+)x(\d+)/
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[[_ | match]] = Regex.scan(pattern, claim)
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[id, x, y, xwidth, ywidth] = Enum.map(match, &String.to_integer(&1))
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{id, x, y, xwidth, ywidth}
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end
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def part_one(input) do
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claims =
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String.split(input, "\n")
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|> Enum.filter(&(&1 != ""))
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|> Enum.map(&DayThree.parse_claim/1)
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dupes = new_doubles(claims)
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area_with =
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dupes
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|> Enum.map(fn {_, {_, _, dx, dy}} -> dx * dy end)
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|> List.foldl(0, &+/2)
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area_with
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end
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def new_doubles(claims) do
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Enum.map(claims, fn {id1, x1, y1, dx1, dy1} ->
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Enum.map(claims, fn {id2, x2, y2, dx2, dy2} ->
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{{:id, id1, id2}, intersect({id1, x1, y1, dx1, dy1}, {id2, x2, y2, dx2, dy2})}
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end)
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|> Enum.filter(fn {_, square} -> square != nil end)
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end)
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|> List.flatten()
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|> Enum.filter(fn {_, square} -> square != nil end)
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end
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def intersect({id1, x1, y1, dx1, dy1}, {id2, x2, y2, dx2, dy2}) do
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if id1 == id2 do
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nil
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else
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intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2}, true)
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end
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end
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def intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2}, ignore \\ false) do
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if {x1, y1, dx1, dy1} == {x2, y2, dx2, dy2} && not ignore do
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nil
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else
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xe1 = x1 + dx1
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xe2 = x2 + dx2
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ye1 = y1 + dy1
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if x2 <= xe1 && y2 <= ye1 && x2 >= x1 && y2 >= y1 do
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{y2, x2, xe1 - x2, ye1 - y2}
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else
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if xe2 >= x1 && y2 <= ye1 && x2 <= x1 && y2 >= y1 do
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{x1, y2, xe2 - x1, ye1 - y2}
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else
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nil
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end
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end
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end
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end
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def part_two(input) do
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claims =
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String.split(input, "\n")
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|> Enum.filter(&(&1 != ""))
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|> Enum.map(&DayThree.parse_claim/1)
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dupes =
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new_doubles(claims)
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|> Enum.dedup()
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|> Enum.map(fn {{:id, id1, id2}, _} -> [id1, id2] end)
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|> List.flatten()
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claim_id = Enum.map(claims, fn {id, _, _, _, _} -> id end)
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[id] = Enum.filter(claim_id, &(not Enum.member?(dupes, &1)))
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id
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end
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end
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{:ok, content} = File.read("input3.txt")
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IO.puts("Part 1 (most likely incorrect): #{DayThree.part_one(content)}")
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IO.puts("Part 2: #{DayThree.part_two(content)}")
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