problems/day21.html

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  17 Oh, hello!  Funny seeing you here.
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  19 I appreciate your enthusiasm, but you aren't going to find much down here.
  20 There certainly aren't clues to any of the puzzles.  The best surprises don't
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  23 Please be careful with automated requests; I'm not a massive company, and I can
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  26 If you're curious about how Advent of Code works, it's running on some custom
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  31 The puzzles are most of the work; preparing a new calendar and a new set of
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  38 - Eric Wastl
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  91 <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://teespring.com/stores/advent-of-code" target="_blank">[Shop]</a></li><li><a href="/2022/settings">[Settings]</a></li><li><a href="/2022/auth/logout">[Log Out]</a></li></ul></nav><div class="user">Neil Smith <a href="/2022/support" class="supporter-badge" title="Advent of Code Supporter">(AoC++)</a> <span class="star-count">42*</span></div></div><div><h1 class="title-event">&nbsp;&nbsp;&nbsp;<span class="title-event-wrap">int y=</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>
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  98 <article class="day-desc"><h2>--- Day 21: Monkey Math ---</h2><p>The <a href="11">monkeys</a> are back! You're worried they're going to try to steal your stuff again, but it seems like they're just holding their ground and making various monkey noises at you.</p>
  99 <p>Eventually, one of the elephants realizes you don't speak monkey and comes over to interpret. As it turns out, they overheard you talking about trying to find the grove; they can show you a shortcut if you answer their <em>riddle</em>.</p>
 100 <p>Each monkey is given a <em>job</em>: either to <em>yell a specific number</em> or to <em>yell the result of a math operation</em>. All of the number-yelling monkeys know their number from the start; however, the math operation monkeys need to wait for two other monkeys to yell a number, and those two other monkeys might <em>also</em> be waiting on other monkeys.</p>
 101 <p>Your job is to <em>work out the number the monkey named <code>root</code> will yell</em> before the monkeys figure it out themselves.</p>
 102 <p>For example:</p>
 103 <pre><code>root: pppw + sjmn
 104 dbpl: 5
 105 cczh: sllz + lgvd
 106 zczc: 2
 107 ptdq: humn - dvpt
 108 dvpt: 3
 109 lfqf: 4
 110 humn: 5
 111 ljgn: 2
 112 sjmn: drzm * dbpl
 113 sllz: 4
 114 pppw: cczh / lfqf
 115 lgvd: ljgn * ptdq
 116 drzm: hmdt - zczc
 117 hmdt: 32
 118 </code></pre>
 119 <p>Each line contains the name of a monkey, a colon, and then the job of that monkey:</p>
 120 <ul>
 121 <li>A lone number means the monkey's job is simply to yell that number.</li>
 122 <li>A job like <code>aaaa + bbbb</code> means the monkey waits for monkeys <code>aaaa</code> and <code>bbbb</code> to yell each of their numbers; the monkey then yells the sum of those two numbers.</li>
 123 <li><code>aaaa - bbbb</code> means the monkey yells <code>aaaa</code>'s number minus <code>bbbb</code>'s number.</li>
 124 <li>Job <code>aaaa * bbbb</code> will yell <code>aaaa</code>'s number multiplied by <code>bbbb</code>'s number.</li>
 125 <li>Job <code>aaaa / bbbb</code> will yell <code>aaaa</code>'s number divided by <code>bbbb</code>'s number.</li>
 126 </ul>
 127 <p>So, in the above example, monkey <code>drzm</code> has to wait for monkeys <code>hmdt</code> and <code>zczc</code> to yell their numbers. Fortunately, both <code>hmdt</code> and <code>zczc</code> have jobs that involve simply yelling a single number, so they do this immediately: <code>32</code> and <code>2</code>. Monkey <code>drzm</code> can then yell its number by finding <code>32</code> minus <code>2</code>: <code><em>30</em></code>.</p>
 128 <p>Then, monkey <code>sjmn</code> has one of its numbers (<code>30</code>, from monkey <code>drzm</code>), and already has its other number, <code>5</code>, from <code>dbpl</code>. This allows it to yell its own number by finding <code>30</code> multiplied by <code>5</code>: <code><em>150</em></code>.</p>
 129 <p>This process continues until <code>root</code> yells a number: <code><em>152</em></code>.</p>
 130 <p>However, your actual situation involves <span title="Advent of Code 2022: Now With Considerably More Monkeys">considerably more monkeys</span>. <em>What number will the monkey named <code>root</code> yell?</em></p>
 131 </article>
 132 <p>Your puzzle answer was <code>21120928600114</code>.</p><article class="day-desc"><h2 id="part2">--- Part Two ---</h2><p>Due to some kind of monkey-elephant-human mistranslation, you seem to have misunderstood a few key details about the riddle.</p>
 133 <p>First, you got the wrong job for the monkey named <code>root</code>; specifically, you got the wrong math operation. The correct operation for monkey <code>root</code> should be <code>=</code>, which means that it still listens for two numbers (from the same two monkeys as before), but now checks that the two numbers <em>match</em>.</p>
 134 <p>Second, you got the wrong monkey for the job starting with <code>humn:</code>. It isn't a monkey - it's <em>you</em>. Actually, you got the job wrong, too: you need to figure out <em>what number you need to yell</em> so that <code>root</code>'s equality check passes. (The number that appears after <code>humn:</code> in your input is now irrelevant.)</p>
 135 <p>In the above example, the number you need to yell to pass <code>root</code>'s equality test is <code><em>301</em></code>. (This causes <code>root</code> to get the same number, <code>150</code>, from both of its monkeys.)</p>
 136 <p><em>What number do you yell to pass <code>root</code>'s equality test?</em></p>
 137 </article>
 138 <p>Your puzzle answer was <code>3453748220116</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
 139 <p>At this point, you should <a href="/2022">return to your Advent calendar</a> and try another puzzle.</p>
 140 <p>If you still want to see it, you can <a href="21/input" target="_blank">get your puzzle input</a>.</p>
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