Advent of Code 2021 Ruby vs Crystal

day01.cr

file = "input.txt"

increases = 0
last_window = nil

a = nil
b = nil
c = nil

File.each_line(file) do |measurement|
  a = b
  b = c
  c = measurement.to_i
  next unless a && b && c

  current_window = a + b + c
  if last_window
    if current_window > last_window
      increases += 1
    end
  end

  last_window = current_window
end

puts increases # 1248

day01.rb

file = "input.txt"

increases = 0
last_window = nil

a = nil
b = nil
c = nil

File.readlines(file).each do |measurement|
  a = b
  b = c
  c = measurement.to_i
  next unless a && b && c

  current_window = a + b + c
  if last_window
    if current_window > last_window
      increases += 1
    end
  end

  last_window = current_window
end

puts increases # 1248

day02.cr

horizontal = 0
depth = 0
aim = 0

File.each_line("input.txt") do |direction|
  dir, delta = direction.split(" ", 2)
  delta = delta.to_i
  case dir
  when "forward"
    horizontal += delta
    depth += (aim * delta)
  when "up"
    aim -= delta
  when "down"
    aim += delta
  else
    raise "Unknown direction: #{dir}"
  end
end

puts "#{horizontal}x#{depth} = #{horizontal*depth}"

day02.rb

horizontal = 0
depth = 0
aim = 0

File.readlines("input.txt").each do |direction|
  dir, delta = direction.split(" ", 2)
  delta = delta.to_i
  case dir
  when "forward"
    horizontal += delta
    depth += (aim * delta)
  when "up"
    aim -= delta
  when "down"
    aim += delta
  else
    raise "Unknown direction: #{dir}"
  end
end

puts "#{horizontal}x#{depth} = #{horizontal*depth}"