From 3e367610c605f8b618ead844b6407c2da1977dcf Mon Sep 17 00:00:00 2001 From: Alpha Chen Date: Sat, 7 Dec 2024 21:20:34 -0800 Subject: [PATCH] [2024][ruby][8.x] --- 2024/ruby/day_08.rb | 68 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 2024/ruby/day_08.rb diff --git a/2024/ruby/day_08.rb b/2024/ruby/day_08.rb new file mode 100644 index 0000000..626922f --- /dev/null +++ b/2024/ruby/day_08.rb @@ -0,0 +1,68 @@ +input = DATA + .readlines(chomp: true).flat_map.with_index {|row, y| + row.chars.map.with_index {|i, x| + [[y,x], i] + } + }.to_h + +freqs = input.values.uniq - %w[.] +pp freqs.flat_map {|freq| + antennae = input.select { _2 == freq }.keys + antennae.combination(2).flat_map {|(ay,ax),(by,bx)| + dy = by - ay + dx = bx - ax + [[ay-dy, ax-dx], [by+dy, bx+dx]] + }.select {|yx| input.has_key?(yx) } +}.uniq.length + +def antinodes(input, a, b) + return enum_for(__method__, input, a, b) unless block_given? + + max_y = input.keys.map(&:first).max + max_x = input.keys.map(&:last).max + + (ay,ax), (by,bx) = a, b + + dy = by - ay + dx = bx - ax + r = Rational(dy, dx) + dy = r.numerator + dx = r.denominator + + y, x = a + loop do + break unless input.has_key?([y,x]) + yield [y,x] + y -= dy + x -= dx + end + + y, x = b + loop do + break unless input.has_key?([y,x]) + yield [y,x] + y += dy + x += dx + end +end + +pp freqs.flat_map {|freq| + antennae = input.select { _2 == freq }.keys + antennae.combination(2).flat_map {|a,b| + antinodes(input, a, b).to_a + } +}.sort.uniq.length + +__END__ +............ +........0... +.....0...... +.......0.... +....0....... +......A..... +............ +............ +........A... +.........A.. +............ +............