aoc2025/day_04/1.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require_relative "grid"

class Main
  def run
    data = []
    $stdin.each_line do |line|
      data << line.chomp
    end

    @sum = 0

    grid = Grid.new(data)
    (0...grid.rows.size).each do |row_index|
      (0...grid.columns.size).each do |column_index|
        next unless grid.cell_at(row_index, column_index).value == "@"

        memo = grid.cell_at(row_index, column_index).neighbours.reject do |cell|
          grid.cell_at(cell.row, cell.column).value != "@"
        end
        if memo.size < 4
          @sum += 1
        end
      end
    end

    puts @sum
  end
end

Main.new.run