2015 day 3 ruby

ruby/2015/3/bin/problem

@@ -0,0 +1,12 @@
+#/usr/bin/env ruby
+
+require "santa"
+
+directions = STDIN.read.chomp
+santa = Santa.for(directions)
+santa.run!
+puts "Part 1: #{santa.visited_houses.length}"
+
+squad = Santa::Squad.for(directions, 2)
+squad.run!
+puts "Part 2: #{squad.visited_houses.length}"

ruby/2015/3/lib/santa.rb

@@ -0,0 +1,57 @@
+require "set"
+
+class Santa
+  attr_reader :visited_houses, :directions, :x, :y
+
+  def initialize(directions, vh=Set.new)
+    @directions = directions
+    @visited_houses = vh
+    @x = 0
+    @y = 0
+  end
+
+  def self.for(string)
+    new string.split("")
+  end
+
+  def handle_direction!(direction)
+    case direction
+    when "^"
+      @y -= 1
+    when "v"
+      @y += 1
+    when "<"
+      @x -= 1
+    when ">"
+      @x += 1
+    end
+    @visited_houses.add [x, y]
+  end
+
+  def run!
+    @visited_houses.add [x, y]
+
+    directions.each do |direction|
+      handle_direction! direction
+    end
+  end
+
+  class Squad
+    attr_reader :directions, :santas, :visited_houses
+    def initialize(directions, count)
+      @directions = directions
+      @visited_houses = Set.new
+      @santas = 1.upto(count).map { Santa.new nil, @visited_houses }
+    end
+
+    def self.for(string, count)
+      new string.split(""), count
+    end
+
+    def run!
+      directions.each_with_index do |direction, index|
+        santas[index % 2].handle_direction! direction
+      end
+    end
+  end
+end