I've been solving all of these in Elixir thus far, and it's been pretty fun! Day 3 is the first time I dealt with "off by one" errors...
parse_claim = fn line -> line |> String.split(~r/[#@,:x\n ]/, trim: true) |> Enum.map(&Integer.parse/1) |> Enum.map(& elem(&1,0)) end claims = File.stream!("day3.txt") |> Enum.map(parse_claim) grid = claims |> Enum.flat_map(fn [claim, left, top, width, height] -> for x <- left..left+width-1, y <- top..top+height-1, do: {claim, x, y} end) |> Enum.reduce(%{}, fn {claim, x, y}, acc -> Map.update(acc, {x,y}, [claim], &[claim | &1]) end) part1 = fn -> grid |> Enum.count(fn {_k,v} -> Enum.count(v) > 1 end) end IO.puts "Part 1: #{part1.()}" part2 = fn -> singles = grid |> Enum.filter(fn {_k,v} -> Enum.count(v) == 1 end) |> Enum.group_by(fn {_k,[v]} -> v end, fn _ -> true end) |> Enum.map(fn {k, v} -> {k, Enum.count(v, & &1)} end) |> Map.new() claims |> Enum.find(fn [claim, _, _, w, h] -> Map.get(singles, claim) == w * h end) |> hd() |> Integer.to_string() end IO.puts "Part 2: #{part2.()}"
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I've been solving all of these in Elixir thus far, and it's been pretty fun! Day 3 is the first time I dealt with "off by one" errors...