2022 day 7 part 1

Author: Robb Kidd

2022/ruby/Gemfile

@@ -4,6 +4,7 @@ source "https://rubygems.org"
 
 git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
+gem "rake"
 gem "pry"
 gem "yard-doctest"
 gem "priority_queue_cxx"

2022/ruby/Gemfile.lock

@@ -8,6 +8,7 @@ GEM
     pry (0.14.1)
       coderay (~> 1.1)
       method_source (~> 1.0)
+    rake (13.0.6)
     webrick (1.7.0)
     yard (0.9.28)
       webrick (~> 1.7.0)
@@ -17,11 +18,13 @@ GEM
 
 PLATFORMS
   arm64-darwin-22
+  ruby
 
 DEPENDENCIES
   priority_queue_cxx
   pry
+  rake
   yard-doctest
 
 BUNDLED WITH
-   2.3.7
+   2.3.26

2022/ruby/day07.rb

@@ -0,0 +1,86 @@
+class Day07
+  def self.go
+    day = new
+    puts "Part 1: #{day.part1}"
+    puts "Part 2: #{day.part2}"
+  end
+
+  def initialize(input=nil)
+    @input = input || real_input
+    @dirs = parse_input
+  end
+
+  # @example
+  #   day.part1 #=> 95_437
+  def part1
+    @dirs
+      .map { |dir_name, _|
+        dirs
+          .select{ |subdir, _| subdir.start_with?(dir_name) }
+          .map{|dir, files| files.empty? ? 0 : files.map{|name,size| size}.reduce(&:+)}
+          .reduce(&:+)
+      }
+      .select{ |dir_size| dir_size < 100_000 }
+      .reduce(&:+)
+  end
+
+  def part2
+  end
+
+  def parse_input
+    cwd = "root"
+    @input
+      .split("$ ")
+      .each_with_object({}) { |cmd_and_output, dirs|
+        lines = cmd_and_output.split("\n")
+        cmd = lines.shift
+        case cmd 
+        when "cd /"
+          cwd = "root"
+        when "cd .."
+          cwd = cwd.split("/")[0..-2].join("/")
+          cwd = "root" if cwd == ""
+        when /cd (\w*)/
+          cwd += "/#{$1}"
+        when "ls"
+          dirs[cwd] ||= { }
+          lines
+            .reject { |line| line.start_with?("dir")}
+            .map { |line| line.split(" ") }
+            .each { |size, filename| dirs[cwd][filename] = size.to_i }
+        else
+          :do_nothing
+        end
+      }
+  end
+
+  def real_input
+    File.read('../inputs/day07-input.txt')
+  end
+
+  EXAMPLE_INPUT = <<~INPUT
+    $ cd /
+    $ ls
+    dir a
+    14848514 b.txt
+    8504156 c.dat
+    dir d
+    $ cd a
+    $ ls
+    dir e
+    29116 f
+    2557 g
+    62596 h.lst
+    $ cd e
+    $ ls
+    584 i
+    $ cd ..
+    $ cd ..
+    $ cd d
+    $ ls
+    4060174 j
+    8033020 d.log
+    5626152 d.ext
+    7214296 k
+  INPUT
+end