day3.rb

#!/usr/bin/env ruby

map = {}
xpos = 0
ypos = 0

xpos_robo = 0
ypos_robo = 0

map[0] = {}
map[0][0] = 1

robo = false
STDIN.each_char do |c|
  if robo
    xpos_robo += 1 if c == '>'
    xpos_robo -= 1 if c == '<'
    ypos_robo += 1 if c == '^'
    ypos_robo -= 1 if c == 'v'
  map[xpos_robo] = {} if map[xpos_robo].nil?
  map[xpos_robo][ypos_robo] = 0 if map[xpos_robo][ypos_robo].nil?
  map[xpos_robo][ypos_robo] += 1
  else
    xpos += 1 if c == '>'
    xpos -= 1 if c == '<'
    ypos += 1 if c == '^'
    ypos -= 1 if c == 'v'
  map[xpos] = {} if map[xpos].nil?
  map[xpos][ypos] = 0 if map[xpos][ypos].nil?
  map[xpos][ypos] += 1
  end
  robo = !robo
end

puts map.values.map(&:size).reduce(&:+)