advent-of-code/2024/ruby/day_13.rb

require "matrix"

input = DATA.read

machines = input.split("\n\n")
  .map {|machine| machine.scan(/\d+/).map(&:to_i).each_slice(2).to_a }

def wins(machine)
  *ab, c = machine
  a, b = (Matrix.columns(ab).inverse * Matrix.column_vector(c)).to_a.flatten
  if [a, b].all? { _1.denominator == 1 }
    [a, b].map(&:to_i)
  else
    nil
  end
end

pp machines.map { wins(_1) }.compact.sum { 3 * _1 + _2 }

pp machines
  .map {|a,b,c| [a,b,c.map { _1 + 10_000_000_000_000 }] }
  .map { wins(_1) }.compact.sum { 3 * _1 + _2 }

__END__
Button A: X+94, Y+34
Button B: X+22, Y+67
Prize: X=10000000008400, Y=10000000005400

Button A: X+26, Y+66
Button B: X+67, Y+21
Prize: X=10000000012748, Y=10000000012176

Button A: X+17, Y+86
Button B: X+84, Y+37
Prize: X=10000000007870, Y=10000000006450

Button A: X+69, Y+23
Button B: X+27, Y+71
Prize: X=10000000018641, Y=10000000010279