1 files changed, 76 insertions, 0 deletions
diff --git a/day07/part2.rb b/day07/part2.rb
new file mode 100644
index 0000000..562629f
--- /dev/null
+++ b/day07/part2.rb
@@ -0,0 +1,76 @@
+lines = $stdin.readlines.map(&:strip)
+
+class FSObj
+  attr_reader :name
+end
+
+class FSDir < FSObj
+  def initialize(name, parent = self)
+    @name = name
+    @parent = parent
+    @entries = []
+  end
+
+  attr_reader :parent
+
+  def add_entry(obj)
+    @entries.push(obj)
+  end
+
+  def find_entry(name)
+    @entries.select{|ent|ent.name == name}[0]
+  end
+
+  def subdirs
+    @entries.select{|ent|ent.class == FSDir}
+  end
+
+  def size
+    @entries.map(&:size).sum
+  end
+end
+
+class FSFile < FSObj
+  def initialize(name, size)
+    @name = name
+    @size = size
+  end
+
+  attr_reader :size
+end
+
+root = FSDir.new(?/)
+current = root
+
+lines.each do |line|
+  case line
+  when "$ ls"
+    next
+  when "$ cd /"
+    next
+  when "$ cd .."
+    current = current.parent
+  when /\A\$ cd (.+)\Z/
+    current = current.find_entry($1)
+  when /\Adir (.+)\Z/
+    current.add_entry(FSDir.new($1, current))
+  when /\A(\d+) (.+)\Z/
+    current.add_entry(FSFile.new($2, $1.to_i))
+  end
+end
+
+disc = 70_000_000
+updt = 30_000_000
+free = disc - root.size
+need = updt - free
+
+dirs = [root]
+bigenough = []
+
+until dirs.empty? do
+  this = dirs.shift
+  bigenough.push(this) if this.size >= need
+  dirs.push(*this.subdirs)
+end
+
+puts bigenough.map(&:size).min