day_03.html

<!DOCTYPE html>
<html lang="en-us">
<head>
<meta charset="utf-8"/>
<title>Day 3 - Advent of Code 2024</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><!--




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 a massive company, 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, 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; preparing a new calendar and a new set of
puzzles each year takes all of my free time for 4-5 months. 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 @was.tl on Bluesky, @ericwastl@hachyderm.io on
Mastodon, and @ericwastl on Twitter.

- Eric Wastl


















































-->
<body>
<header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2024/about">[About]</a></li><li><a href="/2024/events">[Events]</a></li><li><a href="https://cottonbureau.com/people/advent-of-code" target="_blank">[Shop]</a></li><li><a href="/2024/settings">[Settings]</a></li><li><a href="/2024/auth/logout">[Log Out]</a></li></ul></nav><div class="user">ggplijter <span class="star-count">5*</span></div></div><div><h1 class="title-event">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="title-event-wrap">λy.</span><a href="/2024">2024</a><span class="title-event-wrap"></span></h1><nav><ul><li><a href="/2024">[Calendar]</a></li><li><a href="/2024/support">[AoC++]</a></li><li><a href="/2024/sponsors">[Sponsors]</a></li><li><a href="/2024/leaderboard">[Leaderboard]</a></li><li><a href="/2024/stats">[Stats]</a></li></ul></nav></div></header>

<div id="sidebar">
<div id="sponsor"><div class="quiet">Our <a href="/2024/sponsors">sponsors</a> help make Advent of Code possible:</div><div class="sponsor"><a href="/2024/sponsors/redirect?url=https%3A%2F%2Fwww%2Erewe%2Ddigital%2Ecom%2Fen" target="_blank" onclick="if(ga)ga('send','event','sponsor','sidebar',this.href);" rel="noopener">REWE digital</a> - Ho Ho Home of IT: Give yourself a gift and reimagine the digital future of retail in Germany, Austria, Bulgaria or Spain with us!</div></div>
</div><!--/sidebar-->

<main>
<article class="day-desc"><h2>--- Day 3: Mull It Over ---</h2><p>"Our computers are having issues, so I have no idea if we have any Chief Historians <span title="There's a spot reserved for Chief Historians between the green toboggans and the red toboggans. They've never actually had any Chief Historians in stock, but it's best to be prepared.">in stock</span>! You're welcome to check the warehouse, though," says the mildly flustered shopkeeper at the <a href="/2020/day/2">North Pole Toboggan Rental Shop</a>. The Historians head out to take a look.</p>
<p>The shopkeeper turns to you. "Any chance you can see why our computers are having issues again?"</p>
<p>The computer appears to be trying to run a program, but its memory (your puzzle input) is <em>corrupted</em>. All of the instructions have been jumbled up!</p>
<p>It seems like the goal of the program is just to <em>multiply some numbers</em>. It does that with instructions like <code>mul(X,Y)</code>, where <code>X</code> and <code>Y</code> are each 1-3 digit numbers. For instance, <code>mul(44,46)</code> multiplies <code>44</code> by <code>46</code> to get a result of <code>2024</code>. Similarly, <code>mul(123,4)</code> would multiply <code>123</code> by <code>4</code>.</p>
<p>However, because the program's memory has been corrupted, there are also many invalid characters that should be <em>ignored</em>, even if they look like part of a <code>mul</code> instruction. Sequences like <code>mul(4*</code>, <code>mul(6,9!</code>, <code>?(12,34)</code>, or <code>mul ( 2 , 4 )</code> do <em>nothing</em>.</p>
<p>For example, consider the following section of corrupted memory:</p>
<pre><code>x<em>mul(2,4)</em>%&mul[3,7]!@^do_not_<em>mul(5,5)</em>+mul(32,64]then(<em>mul(11,8)mul(8,5)</em>)</code></pre>
<p>Only the four highlighted sections are real <code>mul</code> instructions. Adding up the result of each instruction produces <code><em>161</em></code> (<code>2*4 + 5*5 + 11*8 + 8*5</code>).</p>
<p>Scan the corrupted memory for uncorrupted <code>mul</code> instructions. <em>What do you get if you add up all of the results of the multiplications?</em></p>
</article>
<p>Your puzzle answer was <code>164730528</code>.</p><p class="day-success">The first half of this puzzle is complete! It provides one gold star: *</p>
<article class="day-desc"><h2 id="part2">--- Part Two ---</h2><p>As you scan through the corrupted memory, you notice that some of the conditional statements are also still intact. If you handle some of the uncorrupted conditional statements in the program, you might be able to get an even more accurate result.</p>
<p>There are two new instructions you'll need to handle:</p>
<ul>
<li>The <code>do()</code> instruction <em>enables</em> future <code>mul</code> instructions.</li>
<li>The <code>don't()</code> instruction <em>disables</em> future <code>mul</code> instructions.</li>
</ul>
<p>Only the <em>most recent</em> <code>do()</code> or <code>don't()</code> instruction applies. At the beginning of the program, <code>mul</code> instructions are <em>enabled</em>.</p>
<p>For example:</p>
<pre><code>x<em>mul(2,4)</em>&mul[3,7]!^<em>don't()</em>_mul(5,5)+mul(32,64](mul(11,8)un<em>do()</em>?<em>mul(8,5)</em>)</code></pre>
<p>This corrupted memory is similar to the example from before, but this time the <code>mul(5,5)</code> and <code>mul(11,8)</code> instructions are <em>disabled</em> because there is a <code>don't()</code> instruction before them. The other <code>mul</code> instructions function normally, including the one at the end that gets re-<em>enabled</em> by a <code>do()</code> instruction.</p>
<p>This time, the sum of the results is <code><em>48</em></code> (<code>2*4 + 8*5</code>).</p>
<p>Handle the new instructions; <em>what do you get if you add up all of the results of just the enabled multiplications?</em></p>
</article>
<form method="post" action="3/answer"><input type="hidden" name="level" value="2"/><p>Answer: <input type="text" name="answer" autocomplete="off"/> <input type="submit" value="[Submit]"/></p></form>
<p>Although it hasn't changed, you can still <a href="3/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://bsky.app/intent/compose?text=I%27ve+completed+Part+One+of+%22Mull+It+Over%22+%2D+Day+3+%2D+Advent+of+Code+2024+%23AdventOfCode+https%3A%2F%2Fadventofcode%2Ecom%2F2024%2Fday%2F3" target="_blank">Bluesky</a>
  <a href="https://twitter.com/intent/tweet?text=I%27ve+completed+Part+One+of+%22Mull+It+Over%22+%2D+Day+3+%2D+Advent+of+Code+2024&amp;url=https%3A%2F%2Fadventofcode%2Ecom%2F2024%2Fday%2F3&amp;related=ericwastl&amp;hashtags=AdventOfCode" target="_blank">Twitter</a>
  <a href="javascript:void(0);" onclick="var ms; try{ms=localStorage.getItem('mastodon.server')}finally{} if(typeof ms!=='string')ms=''; ms=prompt('Mastodon Server?',ms); if(typeof ms==='string' && ms.length){this.href='https://'+ms+'/share?text=I%27ve+completed+Part+One+of+%22Mull+It+Over%22+%2D+Day+3+%2D+Advent+of+Code+2024+%23AdventOfCode+https%3A%2F%2Fadventofcode%2Ecom%2F2024%2Fday%2F3';try{localStorage.setItem('mastodon.server',ms);}finally{}}else{return false;}" target="_blank">Mastodon</a
></span>]</span> this puzzle.</p>
</main>

<!-- ga -->
<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>
<!-- /ga -->
</body>
</html>