CINXE.COM

<!DOCTYPE html> <html lang="en-us"> <head> <meta charset="utf-8"/> <title>Day 7 - Advent of Code 2022</title> <link rel="stylesheet" type="text/css" href="/static/style.css?31"/> <link rel="stylesheet alternate" type="text/css" href="/static/highcontrast.css?1" title="High Contrast"/> <link rel="shortcut icon" href="/favicon.png"/> <script>window.addEventListener('click', function(e,s,r){if(e.target.nodeName==='CODE'&&e.detail===3){s=window.getSelection();s.removeAllRanges();r=document.createRange();r.selectNodeContents(e.target);s.addRange(r);}});</script> </head> <body> <header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2022/about">[About]</a></li><li><a href="/2022/events">[Events]</a></li><li><a href="https://cottonbureau.com/people/advent-of-code" target="_blank">[Shop]</a></li><li><a href="/2022/auth/login">[Log In]</a></li></ul></nav></div><div><h1 class="title-event"> <span class="title-event-wrap">{'year':</span><a href="/2022">2022</a><span class="title-event-wrap">}</span></h1><nav><ul><li><a href="/2022">[Calendar]</a></li><li><a href="/2022/support">[AoC++]</a></li><li><a href="/2022/sponsors">[Sponsors]</a></li><li><a href="/2022/leaderboard">[Leaderboard]</a></li><li><a href="/2022/stats">[Stats]</a></li></ul></nav></div></header> <div id="sidebar"> <div id="sponsor"><div class="quiet">Our <a href="/2022/sponsors">sponsors</a> help make Advent of Code possible:</div><div class="sponsor"><a href="/2022/sponsors/redirect?url=https%3A%2F%2Fahrefs%2Ecom%2Fabout" target="_blank" onclick="if(ga)ga('send','event','sponsor','sidebar',this.href);" rel="noopener">Ahrefs</a> - Work on the next general purpose search engine, a world-class crawler, and real big data. Leveraging bleeding-edge hardware and advanced programming technologies. From anywhere in the world. OCaml, ReasonML, Dlang, C++</div></div> </div> <main> <article class="day-desc"><h2>--- Day 7: No Space Left On Device ---</h2><p>You can hear birds chirping and raindrops hitting leaves as the expedition proceeds. Occasionally, you can even hear much louder sounds in the distance; how big do the animals get out here, anyway?</p> <p>The device the Elves gave you has problems with more than just its communication system. You try to run a system update:</p> <pre><code>$ system-update --please --pretty-please-with-sugar-on-top <span title="E099 PROGRAMMER IS OVERLY POLITE">Error</span>: No space left on device </code></pre> <p>Perhaps you can delete some files to make space for the update?</p> <p>You browse around the filesystem to assess the situation and save the resulting terminal output (your puzzle input). For example:</p> <pre><code>$ 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 </code></pre> <p>The filesystem consists of a tree of files (plain data) and directories (which can contain other directories or files). The outermost directory is called <code>/</code>. You can navigate around the filesystem, moving into or out of directories and listing the contents of the directory you're currently in.</p> <p>Within the terminal output, lines that begin with <code>$</code> are <em>commands you executed</em>, very much like some modern computers:</p> <ul> <li><code>cd</code> means <em>change directory</em>. This changes which directory is the current directory, but the specific result depends on the argument: <ul> <li><code>cd x</code> moves <em>in</em> one level: it looks in the current directory for the directory named <code>x</code> and makes it the current directory.</li> <li><code>cd ..</code> moves <em>out</em> one level: it finds the directory that contains the current directory, then makes that directory the current directory.</li> <li><code>cd /</code> switches the current directory to the outermost directory, <code>/</code>.</li> </ul> </li> <li><code>ls</code> means <em>list</em>. It prints out all of the files and directories immediately contained by the current directory: <ul> <li><code>123 abc</code> means that the current directory contains a file named <code>abc</code> with size <code>123</code>.</li> <li><code>dir xyz</code> means that the current directory contains a directory named <code>xyz</code>.</li> </ul> </li> </ul> <p>Given the commands and output in the example above, you can determine that the filesystem looks visually like this:</p> <pre><code>- / (dir) - a (dir) - e (dir) - i (file, size=584) - f (file, size=29116) - g (file, size=2557) - h.lst (file, size=62596) - b.txt (file, size=14848514) - c.dat (file, size=8504156) - d (dir) - j (file, size=4060174) - d.log (file, size=8033020) - d.ext (file, size=5626152) - k (file, size=7214296) </code></pre> <p>Here, there are four directories: <code>/</code> (the outermost directory), <code>a</code> and <code>d</code> (which are in <code>/</code>), and <code>e</code> (which is in <code>a</code>). These directories also contain files of various sizes.</p> <p>Since the disk is full, your first step should probably be to find directories that are good candidates for deletion. To do this, you need to determine the <em>total size</em> of each directory. The total size of a directory is the sum of the sizes of the files it contains, directly or indirectly. (Directories themselves do not count as having any intrinsic size.)</p> <p>The total sizes of the directories above can be found as follows:</p> <ul> <li>The total size of directory <code>e</code> is <em>584</em> because it contains a single file <code>i</code> of size 584 and no other directories.</li> <li>The directory <code>a</code> has total size <em>94853</em> because it contains files <code>f</code> (size 29116), <code>g</code> (size 2557), and <code>h.lst</code> (size 62596), plus file <code>i</code> indirectly (<code>a</code> contains <code>e</code> which contains <code>i</code>).</li> <li>Directory <code>d</code> has total size <em>24933642</em>.</li> <li>As the outermost directory, <code>/</code> contains every file. Its total size is <em>48381165</em>, the sum of the size of every file.</li> </ul> <p>To begin, find all of the directories with a total size of <em>at most 100000</em>, then calculate the sum of their total sizes. In the example above, these directories are <code>a</code> and <code>e</code>; the sum of their total sizes is <code><em>95437</em></code> (94853 + 584). (As in this example, this process can count files more than once!)</p> <p>Find all of the directories with a total size of at most 100000. <em>What is the sum of the total sizes of those directories?</em></p> </article> <p>To play, please identify yourself via one of these services:</p> <p><a href="/auth/github">[GitHub]</a> <a href="/auth/google">[Google]</a> <a href="/auth/twitter">[Twitter]</a> <a href="/auth/reddit">[Reddit]</a> <span class="quiet">- <a href="/about#faq_auth">[How Does Auth Work?]</a></span></p> </main>  <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-69522494-1', 'auto'); ga('set', 'anonymizeIp', true); ga('send', 'pageview'); </script>  </body> </html>