aoc2025/day_06/2.rb

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

require "stringio"

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

    problems = Hash.new(0)
    count = 0
    problems[count] = Hash.new(0)

    num_map.transpose.each do |chars|
      if chars.uniq == [" "]
        count += 1
        problems[count] = Hash.new(0)
        next
      end

      num_str = StringIO.new
      chars.each do |ch|
        if ch.match?(/\d/)
          num_str.write(ch)
        else
          problems[count][:op] = [] unless problems[count].key?(:op)
          problems[count][:op] << ch.to_sym unless ch == " "
        end
      end
      problems[count][:nums] = [] unless problems[count].key?(:nums)
      problems[count][:nums] << num_str.string.to_i unless num_str.string.empty?
    end

    @sum = 0
    problems.each do |_, data|
      @sum += recurse(data[:nums], data[:op].first)
    end

    puts @sum
  end

  def recurse(nums, op)
    return nums.first if nums.size == 1

    num1, num2 = nums.shift(2)

    case op.to_sym
    when :+
      nums.unshift(num1 + num2)
    when :-
      nums.unshift(num1 - num2)
    when :*
      nums.unshift(num1 * num2)
    when :/
      if nums[1] == 0
        raise "Division by zero"
      end
      nums.unshift(num1 / num2)
    end

    recurse(nums, op)
  end
end

Main.new.run