Day 12 Ruby solutions

Author: creideiki

12-1.rb

@@ -0,0 +1,61 @@
+#!/usr/bin/env ruby
+
+class Map
+  attr_accessor :neighbours
+  attr_accessor :paths
+
+  def initialize
+    @neighbours = Hash.new { Array.new }
+    @paths = -1
+  end
+
+  def connect(cave1, cave2)
+    n1 = @neighbours[cave1]
+    n2 = @neighbours[cave2]
+
+    n1.append cave2 unless n1.any? cave2
+    n2.append cave1 unless n2.any? cave1
+
+    @neighbours[cave1] = n1
+    @neighbours[cave2] = n2
+  end
+
+  def visit(cave, path)
+    if cave == 'end'
+      @paths += 1
+    else
+      @neighbours[cave].each { |n| visit(n, path + [cave]) unless path.any? n.downcase }
+    end
+  end
+
+  def count_paths
+    return @paths unless @paths.negative?
+
+    @paths = 0
+    visit('start', [])
+    @paths
+  end
+
+  def to_s
+    s = "<#{self.class} (#{@paths}):\n"
+    @neighbours.each do |cave, neighbours|
+      s += "#{cave} -> #{neighbours}\n"
+    end
+    s += '>'
+    s
+  end
+
+  def inspect
+    to_s
+  end
+end
+
+map = Map.new
+
+input = File.read('12.input').lines.map(&:strip).map { |row| (row.split '-') }
+
+input.each do |conn|
+  map.connect conn[0], conn[1]
+end
+
+print map.count_paths, "\n"

12-2.rb

@@ -0,0 +1,73 @@
+#!/usr/bin/env ruby
+
+class Map
+  attr_accessor :neighbours
+  attr_accessor :paths
+
+  def initialize
+    @neighbours = Hash.new { Array.new }
+    @paths = -1
+  end
+
+  def connect(cave1, cave2)
+    n1 = @neighbours[cave1]
+    n2 = @neighbours[cave2]
+
+    n1.append cave2 unless n1.any? cave2
+    n2.append cave1 unless n2.any? cave1
+
+    @neighbours[cave1] = n1
+    @neighbours[cave2] = n2
+  end
+
+  def visit(cave, path)
+    if cave == 'end'
+      @paths += 1
+    else
+      path += [cave]
+      @neighbours[cave].each do |n|
+        if n == 'start'
+          # Returned to start
+          next
+        elsif n == n.downcase and
+             path.count(n) >= 1 and
+             path.detect { |c| c == c.downcase and path.count(c) > 1 }
+          next
+        else
+          visit(n, path)
+        end
+      end
+    end
+  end
+
+  def count_paths
+    return @paths unless @paths.negative?
+
+    @paths = 0
+    visit('start', [])
+    @paths
+  end
+
+  def to_s
+    s = "<#{self.class} (#{@paths}):\n"
+    @neighbours.each do |cave, neighbours|
+      s += "#{cave} -> #{neighbours}\n"
+    end
+    s += '>'
+    s
+  end
+
+  def inspect
+    to_s
+  end
+end
+
+map = Map.new
+
+input = File.read('12.input').lines.map(&:strip).map { |row| (row.split '-') }
+
+input.each do |conn|
+  map.connect conn[0], conn[1]
+end
+
+print map.count_paths, "\n"