150 lines
6.7 KiB
HTML
150 lines
6.7 KiB
HTML
<!DOCTYPE html>
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<html lang="en-us">
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<head>
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<meta charset="utf-8"/>
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<title>Day 4 - Advent of Code 2025</title>
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<link rel="stylesheet" type="text/css" href="/static/style.css?32"/>
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<link rel="stylesheet alternate" type="text/css" href="/static/highcontrast.css?2" title="High Contrast"/>
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<link rel="shortcut icon" href="/favicon.png"/>
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<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>
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</head><!--
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Oh, hello! Funny seeing you here.
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I appreciate your enthusiasm, but you aren't going to find much down here.
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There certainly aren't clues to any of the puzzles. The best surprises don't
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even appear in the source until you unlock them for real.
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Please be careful with automated requests; I'm not a massive company, and I can
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only take so much traffic. Please be considerate so that everyone gets to play.
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If you're curious about how Advent of Code works, it's running on some custom
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Perl code. Other than a few integrations (auth, analytics, social media), I
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built the whole thing myself, including the design, animations, prose, and all
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of the puzzles.
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The puzzles are most of the work; preparing a new calendar and a new set of
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puzzles takes all of my free time for months every year. A lot of effort went
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into building this thing - I hope you're enjoying playing it as much as I
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enjoyed making it for you!
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If you'd like to hang out, I'm @was.tl on Bluesky and @ericwastl@hachyderm.io
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on Mastodon.
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- Eric Wastl
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-->
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<body>
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<header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2025/about">[About]</a></li><li><a href="/2025/events">[Events]</a></li><li><a href="/2025/shop">[Shop]</a></li><li><a href="/2025/settings">[Settings]</a></li><li><a href="/2025/auth/logout">[Log Out]</a></li></ul></nav><div class="user">buhman</div></div><div><h1 class="title-event"> <span class="title-event-wrap">/^</span><a href="/2025">2025</a><span class="title-event-wrap">$/</span></h1><nav><ul><li><a href="/2025">[Calendar]</a></li><li><a href="/2025/support">[AoC++]</a></li><li><a href="/2025/sponsors">[Sponsors]</a></li><li><a href="/2025/leaderboard/private">[Leaderboards]</a></li><li><a href="/2025/stats">[Stats]</a></li></ul></nav></div></header>
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<div id="sidebar">
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<div id="sponsor"><div class="quiet">Our <a href="/2025/sponsors">sponsors</a> help make Advent of Code possible:</div><div class="sponsor"><a href="/2025/sponsors/redirect?url=https%3A%2F%2Feu1%2Ehubs%2Ely%2FH0q0W730" target="_blank" onclick="if(ga)ga('send','event','sponsor','sidebar',this.href);" rel="noopener">CGI</a> - Join our Software Development Revolution. Discover how AI is transforming the way we build software and how we're building what's next.</div></div>
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</div><!--/sidebar-->
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<main>
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<article class="day-desc"><h2>--- Day 4: Printing Department ---</h2><p>You ride the escalator down to the printing department. They're clearly getting ready for Christmas; they have lots of large rolls of paper everywhere, and there's even a massive printer in the corner (to handle the really <span title="This joke is stupid and I love it.">big</span> print jobs).</p>
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<p>Decorating here will be easy: they can make their own decorations. What you really need is a way to get further into the North Pole base while the elevators are offline.</p>
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<p>"Actually, maybe we can help with that," one of the Elves replies when you ask for help. "We're pretty sure there's a cafeteria on the other side of the back wall. If we could break through the wall, you'd be able to keep moving. It's too bad all of our forklifts are so busy moving those big rolls of paper around."</p>
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<p>If you can optimize the work the forklifts are doing, maybe they would have time to spare to break through the wall.</p>
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<p>The rolls of paper (<code>@</code>) are arranged on a large grid; the Elves even have a helpful diagram (your puzzle input) indicating where everything is located.</p>
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<p>For example:</p>
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<pre><code>..@@.@@@@.
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@@@.@.@.@@
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@@@@@.@.@@
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@.@@@@..@.
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@@.@@@@.@@
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.@@@@@@@.@
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.@.@.@.@@@
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@.@@@.@@@@
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.@@@@@@@@.
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@.@.@@@.@.
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</code></pre>
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<p>The forklifts can only access a roll of paper if there are <em>fewer than four rolls of paper</em> in the eight adjacent positions. If you can figure out which rolls of paper the forklifts can access, they'll spend less time looking and more time breaking down the wall to the cafeteria.</p>
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<p>In this example, there are <code><em>13</em></code> rolls of paper that can be accessed by a forklift (marked with <code>x</code>):</p>
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<pre><code>..xx.xx@x.
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x@@.@.@.@@
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@@@@@.x.@@
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@.@@@@..@.
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x@.@@@@.@x
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.@@@@@@@.@
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.@.@.@.@@@
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x.@@@.@@@@
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.@@@@@@@@.
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x.x.@@@.x.
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</code></pre>
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<p>Consider your complete diagram of the paper roll locations. <em>How many rolls of paper can be accessed by a forklift?</em></p>
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</article>
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<p>To begin, <a href="4/input" target="_blank">get your puzzle input</a>.</p>
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<form method="post" action="4/answer"><input type="hidden" name="level" value="1"/><p>Answer: <input type="text" name="answer" autocomplete="off"/> <input type="submit" value="[Submit]"/></p></form>
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<p>You can also <span class="share">[Share<span class="share-content">on
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<a href="https://bsky.app/intent/compose?text=%22Printing+Department%22+%2D+Day+4+%2D+Advent+of+Code+2025+%23AdventOfCode+https%3A%2F%2Fadventofcode%2Ecom%2F2025%2Fday%2F4" target="_blank">Bluesky</a>
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<a href="https://twitter.com/intent/tweet?text=%22Printing+Department%22+%2D+Day+4+%2D+Advent+of+Code+2025&url=https%3A%2F%2Fadventofcode%2Ecom%2F2025%2Fday%2F4&related=ericwastl&hashtags=AdventOfCode" target="_blank">Twitter</a>
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<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=%22Printing+Department%22+%2D+Day+4+%2D+Advent+of+Code+2025+%23AdventOfCode+https%3A%2F%2Fadventofcode%2Ecom%2F2025%2Fday%2F4';try{localStorage.setItem('mastodon.server',ms);}finally{}}else{return false;}" target="_blank">Mastodon</a
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></span>]</span> this puzzle.</p>
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