Caleb Weeks

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# Advent of Code #11 (in Crystal)

I've been trying to add some meaningful commentary or thoughts along with each of these posts about Crystal, the puzzle, my solution, or coding in general. But today, I've got nothing. The puzzle wasn't all that complicated, and my code isn't all that great.

I gave up after day 11 last year, so hopefully I'll be able to get a little further this year!

Here's my code:

``````input = File.read("input").strip

lines = input.split("\n")

galaxies = lines.map_with_index do |line, row|
line.scan(/#/).map { |match| {row, match.begin} }
end.flatten

empty_rows = (0..(lines.size - 1)).select do |row|
!galaxies.find { |(x, _)| x == row }
end

empty_cols = (0..(lines[0].size - 1)).select do |col|
!galaxies.find { |(_, y)| y == col }
end

expanded_universe = galaxies.map do |x, y|
{
x + empty_rows.select { |row| row < x }.size,
y + empty_cols.select { |col| col < y }.size
}
end

part1 = begin
lengths = 0
expanded_universe.each_cartesian(expanded_universe) do |(x1, y1), (x2, y2)|
if {x1, y1} < {x2, y2}
lengths += (x2 - x1).abs + (y2 - y1).abs
end
end
lengths
end

puts part1

older_universe = galaxies.map do |x, y|
{
x.to_i64 + (empty_rows.select { |row| row < x }.size.to_i64 * 999_999_i64),
y.to_i64 + (empty_cols.select { |col| col < y }.size.to_i64 * 999_999_i64)
}
end

part2 = begin
lengths = 0_i64
older_universe.each_cartesian(older_universe) do |(x1, y1), (x2, y2)|
if {x1, y1} < {x2, y2}
lengths += (x2 - x1).abs + (y2 - y1).abs
end
end
lengths
end

puts part2
``````