Advent of Code day 3

part1_take1.rb

grid = DATA.readlines.map(&:chomp)
max_line = grid.length - 1
max_col = grid.first.length - 1

sum = 0
grid.each_with_index do |line, i|
  tokens = line.scan(/(\D*)(\d+)/).flatten

  offset = 0
  tokens.each.with_index do |token, j|
    is_number = j.odd?

    if is_number
      left = [ offset - 1, 0 ].max
      right = [ offset + token.length, max_col ].min
      over = [ i - 1 , 0 ].max
      under = [ i + 1, max_line ].min

      neighbours = ""
      neighbours += grid[over][left..right]
      neighbours += grid[i][left..right]
      neighbours += grid[under][left..right]

      sum += token.to_i if neighbours.match?(/[^\d.]/)
    end

    offset += token.length
  end
end

puts sum

__END__
Data goes here

part2_take1.rb

grid = DATA.readlines.map(&:chomp)
max_line = grid.length - 1
max_col = grid.first.length - 1

gears_to_numbers = Hash.new { |h, k| h[k] = [] }

grid.each_with_index do |line, i|
  tokens = line.scan(/(\D*)(\d+)/).flatten

  offset = 0
  tokens.each.with_index do |token, j|
    is_number = j.odd?

    if is_number
      left = [ offset - 1, 0 ].max
      right = [ offset + token.length, max_col ].min
      over = [ i - 1 , 0 ].max
      under = [ i + 1, max_line ].min

      [ over, i, under ].uniq.each do |row|
        grid[row][left..right].each_char.with_index(left).each do |c, k|
          next unless c == "*"

          gears_to_numbers[[row, k]] << token.to_i
        end
      end
    end

    offset += token.length
  end
end

puts gears_to_numbers.values.reject { _1.length == 1 }.sum { _1.reduce(:*) }

__END__
Data goes here