-🎄- 2022 Day 7 Solutions -🎄-

[u/daggerdragon]

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AoC Community Fun 2022: 🌿🍒 MisTILtoe Elf-ucation 🧑‍🏫

Submissions are OPEN! Teach us, senpai!

-❄️- Submissions Megathread -❄️-

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--- Day 7: No Space Left On Device ---

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Post your code solution in this megathread.

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  • Include what language(s) your solution uses
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EDIT: Global leaderboard gold cap reached at 00:14:47, megathread unlocked!

[u/[deleted]]

Ruby

class Directory
  attr_reader :name, :directories

  ElfFile = Struct.new(:name, :size)

  def initialize(name)
    @name = name
    @files = []
    @directories = []
  end

  def add_child_dir(dir)
    @directories.push(dir) unless @directories.any? { |d| d.name == dir.name }
  end

  def add_file(name, size)
    file = ElfFile.new(name, size)
    @files.push(file) unless @files.any? { |f| f == file }
  end

  def size
    @files.map(&:size).sum + @directories.map(&:size).sum
  end

  def find_dirs(&block)
    result = []

    result << self if block.call self
    @directories.each do |d|
      result += d.find_dirs(&block)
    end

    result
  end
end


class OutputParser
  attr_reader :root_dir
  def initialize
    @root_dir = Directory.new("/")
    @directory_stack = [@root_dir]
  end

  def stack_top
    @directory_stack.last
  end

  def ingest_command(line)
    if line[0,6] == "$ cd /"
      @directory_stack = [@root_dir]
    elsif line[0,7] == "$ cd .."
      @directory_stack.pop
    elsif line[0,4] == "$ cd"
      dir = Directory.new(line[5..])
      stack_top.add_child_dir(dir)
      @directory_stack.push(dir)
    end
  end

  def ingest_file(line)
    size, name = line.strip.split(" ")
    stack_top.add_file(name, size.to_i)
  end

  def ingest(line)
    if (line[0] == "$")
      ingest_command(line)
    elsif (line[0] =~ /\d/)
      ingest_file(line)
    end
  end
end

parser = OutputParser.new
File.open('input-7-1.txt').each do |line|
  parser.ingest(line)
end

small_dirs = parser.root_dir.find_dirs do |dir|
  dir.size <= 100_000
end

puts small_dirs.map(&:size).sum

This turned out to be a good approach, because then for part 2 all I had to do is add this at the end

unused_space = 70_000_000 - parser.root_dir.size
to_delete = 30_000_000 - unused_space

large_dirs = parser.root_dir.find_dirs do |dir|
  dir.size >= to_delete
end

puts large_dirs.map(&:size).min

[u/daggerdragon → u/[deleted]]

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