4 files changed, 170 insertions, 0 deletions
diff --git a/day13/input b/day13/input
new file mode 100644
index 0000000..a9a659c
--- /dev/null
+++ b/day13/input
@@ -0,0 +1,43 @@
+0: 3
+1: 2
+2: 4
+4: 4
+6: 5
+8: 8
+10: 6
+12: 6
+14: 6
+16: 6
+18: 8
+20: 8
+22: 12
+24: 10
+26: 9
+28: 8
+30: 8
+32: 12
+34: 12
+36: 12
+38: 12
+40: 8
+42: 12
+44: 14
+46: 14
+48: 10
+50: 12
+52: 12
+54: 14
+56: 14
+58: 14
+62: 12
+64: 14
+66: 14
+68: 14
+70: 12
+74: 14
+76: 14
+78: 14
+80: 18
+82: 17
+84: 30
+88: 14
diff --git a/day13/part1 b/day13/part1
new file mode 100755
index 0000000..9af71a6
--- /dev/null
+++ b/day13/part1
@@ -0,0 +1,70 @@
+#!/usr/bin/env ruby
+
+class Firewall
+  class Layer
+    attr_reader :range
+
+    def initialize(range)
+      @scanner_location = 0
+      @scanner_velocity = 1
+      @range = range
+    end
+
+    def move_scanner!
+      if @scanner_location == (@range - 1) then
+        @scanner_velocity = -1
+      elsif @scanner_location == 0 then
+        @scanner_velocity = 1
+      end
+
+      @scanner_location += @scanner_velocity
+    end
+
+    def capturing?
+      return @scanner_location == 0
+    end
+  end
+
+  def initialize
+    @layers = []
+  end
+
+  def add_layer!(depth, range)
+    @layers[depth] = Layer.new(range)
+  end
+
+  def total_depth
+    return @layers.length
+  end
+
+  def severity(loc)
+    return 0 if @layers[loc].nil?
+    return 0 unless @layers[loc].capturing?
+    return loc * @layers[loc].range
+  end
+
+  def tick!
+    @layers.compact.each(&:move_scanner!)
+  end
+end
+
+
+input = $stdin.readlines.map(&:chomp)
+
+firewall = Firewall.new
+
+input.each do |line|
+  depth, range = line.split(': ').map(&:to_i)
+  firewall.add_layer!(depth, range)
+end
+
+myloc = -1
+total_severity = 0
+
+while myloc < firewall.total_depth do
+  myloc += 1
+  total_severity += firewall.severity(myloc)
+  firewall.tick!
+end
+
+puts total_severity
diff --git a/day13/part2.dnw b/day13/part2.dnw
new file mode 100755
index 0000000..af6af5b
--- /dev/null
+++ b/day13/part2.dnw
@@ -0,0 +1,53 @@
+#!/usr/bin/env ruby
+
+class Firewall
+  class Layer
+    def initialize(range)
+      @period = (range - 1) * 2
+    end
+
+    def will_capture_at?(time)
+      return time % @period == 0
+    end
+  end
+
+  def initialize
+    @layers = []
+  end
+
+  def add_layer!(depth, range)
+    @layers[depth] = Layer.new(range)
+  end
+
+  def will_capture_at?(time)
+    (0...@layers.length).each do |i|
+      next if @layers[i].nil?
+      return true if @layers[i].will_capture_at?(time + i)
+    end
+    return false
+  end
+end
+
+
+input = $stdin.readlines.map(&:chomp).map{|l|l.split(': ').map(&:to_i)}
+lcm = input.map(&:last).inject(1, :lcm)
+delay = 0
+
+loop do
+  if delay > lcm then
+    puts "Went past lcm"
+    exit
+  end
+
+  firewall = Firewall.new
+
+  input.each do |line|
+    firewall.add_layer!(line[0], line[1])
+  end
+
+  break unless firewall.will_capture_at?(delay)
+
+  delay += 1
+end
+
+puts delay
diff --git a/day13/test b/day13/test
new file mode 100644
index 0000000..0239024
--- /dev/null
+++ b/day13/test
@@ -0,0 +1,4 @@
+0: 3
+1: 2
+4: 4
+6: 4