Ruby

!ruby@programming.dev [LANGUAGE: Ruby]

I found today really easy thankfully. Hardest part was remembering the language features haha

https://github.com/snowe2010/advent-of-code/blob/master/ruby_aoc/2023/day09/day09.rb

edit: code golfing this one was easy too! man this day really worked out huh

    def get_subsequent_reading(reading)
      puts "passed in readings #{reading}"
      if reading.all?(0)
        reading << 0
      else
        readings = reading.each_cons(2).map do |a, b|
          b - a
        end
        sub_reading = get_subsequent_reading(readings)
        reading << (reading[-1] + sub_reading[-1])
        puts "current reading #{reading}"
        reading
      end
    end
    
    execute(1) do |lines|
      lines.map do |reading|
        get_subsequent_reading(reading.split.map(&:to_i))
      end.map {|arr| arr[-1]}.sum
    end
    
    
    def get_preceeding_readings(reading)
      puts "passed in readings #{reading}"
      if reading.all?(0)
        reading.unshift(0)
      else
        readings = reading.each_cons(2).map do |a, b|
          b - a
        end
        sub_reading = get_preceeding_readings(readings)
        reading.unshift(reading[0] - sub_reading[0])
        puts "current reading #{readings} #{sub_reading}"
        reading
      end
    end
    
    
    execute(2, test_only: false, test_file_suffix: '') do |lines|
      lines.map do |reading|
        get_preceeding_readings(reading.split.map(&:to_i))
      end.map {|arr| arr[0]}.sum
    end

code golf

  a=->r{r.unshift(r.all?(0)?0:(r[0]-a[r.each_cons(2).map{_2-_1}][0]))}
  l.map{a[_1.split.map(&:to_i)]}.map{_1[0]}.sum