Snippet

advent_of_code/2024_8.rb

Code:

# Advent of Code 2024, Day 8: Resonant Collinearity

# https://adventofcode.com/2024/day/8

require_relative './helpers.rb'

def d(a, b)
  Point.new(a.x - b.x, a.y - b.y)
end

def part_one(grid)
  g = copy_grid(grid)
  (grid.flatten.uniq - ['.']).each do |f|
    find_grid(grid, f).combination(2).each do |a, b|
      set_grid(g, d(a, d(b, a)), '#')
      set_grid(g, d(b, d(a, b)), '#')
    end
  end
  g.flatten.count('#')
end

def part_two(grid)
  g = copy_grid(grid)
  (grid.flatten.uniq - ['.']).each do |f|
    find_grid(grid, f).combination(2).each do |a, b|
      d_a, d_b = d(b, a), d(a, b)
      i, j = d(a, d_a), d(b, d_b)
      i = d(i, d_a) while set_grid(g, i, '#')
      j = d(j, d_b) while set_grid(g, j, '#')
    end
  end
   g.flatten.count { |c| c != '.' }
end

def solve(data)
  data.map!(&:chomp).map! { |l| l.chars }
# draw_grid(data) if data.size < 20
  [part_one(copy_grid(data)), part_two(copy_grid(data))]
end

puts solve(get_dataset(year: 2024, day: 8, type: 'example'))
# puts solve(get_dataset(year: 2024, day: 8, type: 'example_2'))
puts solve(get_dataset(year: 2024, day: 8, type: 'example_3'))
puts solve(get_dataset(year: 2024, day: 8, type: 'input'))

Output:

14
34
3
9
278
1067