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+<title>Day 8 - Advent of Code 2018</title>
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+Oh, hello! Funny seeing you here.
+
+I appreciate your enthusiasm, but you aren't going to find much down here.
+There certainly aren't clues to any of the puzzles. The best surprises don't
+even appear in the source until you unlock them for real.
+
+Please be careful with automated requests; I'm not Google, and I can only take
+so much traffic. Please be considerate so that everyone gets to play.
+
+If you're curious about how Advent of Code works, it's running on some custom
+Perl code. Other than a few integrations (auth, analytics, ads, social media),
+I built the whole thing myself, including the design, animations, prose, and
+all of the puzzles.
+
+The puzzles are most of the work; the easiest ones take 3-4 hours each, but the
+harder ones take 6-8 hours, and a few even longer than that. A lot of effort
+went into building this thing - I hope you're enjoying playing it as much as I
+enjoyed making it for you!
+
+If you'd like to hang out, I'm @ericwastl on Twitter.
+
+- Eric Wastl
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+-->
+<body>
+<header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2018/about">[About]</a></li><li><a href="/2018/events">[Events]</a></li><li><a href="https://teespring.com/adventofcode" target="_blank">[Shop]</a></li><li><a href="/2018/settings">[Settings]</a></li><li><a href="/2018/auth/logout">[Log Out]</a></li></ul></nav><div class="user">Neil Smith <a href="/2018/support" class="supporter-badge" title="Advent of Code Supporter">(AoC++)</a> <span class="star-count">16*</span></div></div><div><h1 class="title-event"> <span class="title-event-wrap">var y=</span><a href="/2018">2018</a><span class="title-event-wrap">;</span></h1><nav><ul><li><a href="/2018">[Calendar]</a></li><li><a href="/2018/support">[AoC++]</a></li><li><a href="/2018/sponsors">[Sponsors]</a></li><li><a href="/2018/leaderboard">[Leaderboard]</a></li><li><a href="/2018/stats">[Stats]</a></li></ul></nav></div></header>
+
+<div id="sidebar">
+<div id="sponsor"><div class="quiet">Our <a href="/2018/sponsors">sponsors</a> help make Advent of Code possible:</div><div class="sponsor"><a href="https://rainway.io/" target="_blank" onclick="if(ga)ga('send','event','sponsor','click',this.href);" rel="noopener">Rainway</a> - Play all your favorite PC games anytime, anywhere, across a variety of different devices.</div></div>
+</div><!--/sidebar-->
+
+<main>
+<article class="day-desc"><h2>--- Day 8: Memory Maneuver ---</h2><p>The sleigh is much easier to pull than you'd expect for something its weight. Unfortunately, neither you nor the Elves know <span title="It's North. Obviously.">which way</span> the North Pole is from here.</p>
+<p>You check your wrist device for anything that might help. It seems to have some kind of navigation system! Activating the navigation system produces more bad news: "Failed to start navigation system. Could not read software license file."</p>
+<p>The navigation system's license file consists of a list of numbers (your puzzle input). The numbers define a data structure which, when processed, produces some kind of <a href="https://en.wikipedia.org/wiki/Tree_(data_structure)">tree</a> that can be used to calculate the license number.</p>
+<p>The <em>tree</em> is made up of <em>nodes</em>; a single, outermost node forms the tree's <em>root</em>, and it contains all other nodes in the tree (or contains nodes that contain nodes, and so on).</p>
+<p>Specifically, a node consists of:</p>
+<ul>
+<li>A <em>header</em>, which is always exactly two numbers:
+<ul>
+<li>The quantity of child nodes.</li>
+<li>The quantity of metadata entries.</li>
+</ul>
+<li>Zero or more <em>child nodes</em> (as specified in the header).</li>
+<li>One or more <em>metadata entries</em> (as specified in the header).</li>
+</ul>
+<p>Each child node is itself a node that has its own header, child nodes, and metadata. For example:</p>
+<pre><code>2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2
+A----------------------------------
+ B----------- C-----------
+ D-----
+</code></pre>
+<p>In this example, each node of the tree is also marked with an underline starting with a letter for easier identification. In it, there are four nodes:</p>
+<ul>
+<li><code>A</code>, which has <code>2</code> child nodes (<code>B</code>, <code>C</code>) and <code>3</code> metadata entries (<code>1</code>, <code>1</code>, <code>2</code>).</li>
+<li><code>B</code>, which has <code>0</code> child nodes and <code>3</code> metadata entries (<code>10</code>, <code>11</code>, <code>12</code>).</li>
+<li><code>C</code>, which has <code>1</code> child node (<code>D</code>) and <code>1</code> metadata entry (<code>2</code>).</li>
+<li><code>D</code>, which has <code>0</code> child nodes and <code>1</code> metadata entry (<code>99</code>).</li>
+</ul>
+<p>The first check done on the license file is to simply add up all of the metadata entries. In this example, that sum is <code>1+1+2+10+11+12+2+99=<em>138</em></code>.</p>
+<p><em>What is the sum of all metadata entries?</em></p>
+</article>
+<p>Your puzzle answer was <code>46962</code>.</p><article class="day-desc"><h2 id="part2">--- Part Two ---</h2><p>The second check is slightly more complicated: you need to find the value of the root node (<code>A</code> in the example above).</p>
+<p>The <em>value of a node</em> depends on whether it has child nodes.</p>
+<p>If a node has <em>no child nodes</em>, its value is the sum of its metadata entries. So, the value of node <code>B</code> is <code>10+11+12=33</code>, and the value of node <code>D</code> is <code>99</code>.</p>
+<p>However, if a node <em>does have child nodes</em>, the metadata entries become indexes which refer to those child nodes. A metadata entry of <code>1</code> refers to the first child node, <code>2</code> to the second, <code>3</code> to the third, and so on. The value of this node is the sum of the values of the child nodes referenced by the metadata entries. If a referenced child node does not exist, that reference is skipped. A child node can be referenced multiple time and counts each time it is referenced. A metadata entry of <code>0</code> does not refer to any child node.</p>
+<p>For example, again using the above nodes:</p>
+<ul>
+<li>Node <code>C</code> has one metadata entry, <code>2</code>. Because node <code>C</code> has only one child node, <code>2</code> references a child node which does not exist, and so the value of node <code>C</code> is <code>0</code>.</li>
+<li>Node <code>A</code> has three metadata entries: <code>1</code>, <code>1</code>, and <code>2</code>. The <code>1</code> references node <code>A</code>'s first child node, <code>B</code>, and the <code>2</code> references node <code>A</code>'s second child node, <code>C</code>. Because node B has a value of <code>33</code> and node <code>C</code> has a value of <code>0</code>, the value of node <code>A</code> is <code>33+33+0=<em>66</em></code>.</li>
+</ul>
+<p>So, in this example, the value of the root node is <code>66</code>.</p>
+<p><em>What is the value of the root node?</em></p>
+</article>
+<p>Your puzzle answer was <code>22633</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
+<p>At this point, you should <a href="/2018">return to your advent calendar</a> and try another puzzle.</p>
+<p>If you still want to see it, you can <a href="8/input" target="_blank">get your puzzle input</a>.</p>
+<p>You can also <span class="share">[Share<span class="share-content">on
+ <a href="https://twitter.com/intent/tweet?text=I%27ve+completed+%22Memory+Maneuver%22+%2D+Day+8+%2D+Advent+of+Code+2018&url=https%3A%2F%2Fadventofcode%2Ecom%2F2018%2Fday%2F8&related=ericwastl&hashtags=AdventOfCode" target="_blank">Twitter</a>
+ <a href="http://www.reddit.com/submit?url=https%3A%2F%2Fadventofcode%2Ecom%2F2018%2Fday%2F8&title=I%27ve+completed+%22Memory+Maneuver%22+%2D+Day+8+%2D+Advent+of+Code+2018" target="_blank">Reddit</a
+></span>]</span> this puzzle.</p>
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