2019: Day 6 Part 1

2019-12-06 09:14:15 -08:00 · 2019-12-06 09:14:15 -08:00 · 38c2d697c7
commit 38c2d697c7
parent 1ae1c260f1
2 changed files with 1540 additions and 0 deletions
--- a/2019/day6/input
+++ b/2019/day6/input
--- a/2019/day6/part1.rb
+++ b/2019/day6/part1.rb
@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'set'
+
+class Body
+  attr_reader :name, :satellites
+  def initialize(name)
+    @name = name
+    @satellites = []
+  end
+
+  def <<(satellite)
+    @satellites << satellite
+  end
+
+  def inspect
+    "<Body #{name}, #{satellites.map(&:name).inspect}>"
+  end
+
+  def to_s
+    name
+  end
+
+  def direct_orbits
+    @direct_orbits ||= @satellites.length + @satellites.sum(&:direct_orbits)
+  end
+
+  def indirect_orbits(depth = 0)
+    @indirect_orbits ||= @satellites.sum do |sat|
+      depth + sat.indirect_orbits(depth + 1)
+    end
+  end
+
+  @@registry = {}
+
+  def self.get_or_create(name)
+    if @@registry.key? name
+      @@registry[name]
+    else
+      body = new(name)
+      @@registry[name] = body
+    end
+  end
+
+  def self.get(name)
+    @@registry[name]
+  end
+end
+
+def parse(input)
+  input.lines.map do |line|
+    center_name, satellite_name = line.strip.split(')')
+    center = Body.get_or_create center_name
+    satellite = Body.get_or_create satellite_name
+    center << satellite
+  end
+  Body.get 'COM'
+end
+
+input = File.read(File.join(__dir__, 'input'))
+
+com = parse(input)
+puts com.direct_orbits + com.indirect_orbits