day23.html

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   5 <title>Day 23 - Advent of Code 2016</title>
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  15 Oh, hello!  Funny seeing you here.
  16
  17 I appreciate your enthusiasm, but you aren't going to find much down here.
  18 There certainly aren't clues to any of the puzzles.  The best surprises don't
  19 even appear in the source until you unlock them for real.
  20
  21 Please be careful with automated requests; I'm not Google, and I can only take
  22 so much traffic.  Please be considerate so that everyone gets to play.
  23
  24 If you're curious about how Advent of Code works, it's running on some custom
  25 Perl code. Other than a few integrations (auth, analytics, ads, social media),
  26 I built the whole thing myself, including the design, animations, prose, and
  27 all of the puzzles.
  28
  29 The puzzles probably took the longest; the easiest ones were around 45 minutes
  30 each, but the harder ones took 2-3 hours, and a few even longer than that. A
  31 lot of effort went into building this thing - I hope you're enjoying playing it
  32 as much as I enjoyed making it for you!
  33
  34 If you'd like to hang out, I'm @ericwastl on Twitter.
  35
  36 - Eric Wastl
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  88 <body>
  89 <header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2016/about">[About]</a></li><li><a href="/2016/support">[AoC++]</a></li><li><a href="/2016/events">[Events]</a></li><li><a href="/2016/settings">[Settings]</a></li><li><a href="/2016/auth/logout">[Log Out]</a></li></ul></nav><div class="user">Neil Smith <span class="supporter">(AoC++)</span> <span class="star-count">46*</span></div></div><div><h1 class="title-event">&nbsp;&nbsp;&nbsp;<span class="title-event-wrap">0xffff&amp;</span><a href="/2016">2016</a><span class="title-event-wrap"></span></h1><nav><ul><li><a href="/2016">[Calendar]</a></li><li><a href="/2016/leaderboard">[Leaderboard]</a></li><li><a href="/2016/stats">[Stats]</a></li><li><a href="/2016/sponsors">[Sponsors]</a></li></ul></nav></div></header>
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  92 <div id="sponsor"><div class="quiet">Our <a href="/2016/sponsors">sponsors</a> help make AoC possible:</div><p><a href="https://info.esparklearning.com/join-our-team-full-stack-engineer" target="_blank" onclick="if(ga)ga('send','event','sponsor','click',this.href);">eSpark Learning</a> - Solve the greatest puzzle of our day - transform education</p></div>
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 107 <article class="day-desc"><h2>--- Day 23: Safe Cracking ---</h2><p>This is one of the top floors of the nicest tower in EBHQ. The Easter Bunny's private office is here, complete with a safe hidden behind a painting, and who <em>wouldn't</em> hide a star in a safe behind a painting?</p>
 108 <p>The safe has a digital screen and keypad for code entry. A sticky note attached to the safe has a password hint on it: "eggs". The painting is of a large rabbit coloring some eggs. You see <code>7</code>.</p>
 109 <p>When you go to type the code, though, nothing appears on the display; instead, the keypad comes apart in your hands, apparently having been smashed. Behind it is some kind of socket - one that matches a connector in your <a href="11">prototype computer</a>! You pull apart the smashed keypad and extract the logic circuit, plug it into your computer, and plug your computer into the safe.</p>
 110 </p>Now, you just need to figure out what output the keypad would have sent to the safe. You extract the <a href="12">assembunny code</a> from the logic chip (your puzzle input).</p>
 111 <p>The code looks like it uses <em>almost</em> the same architecture and instruction set that the <a href="12">monorail computer</a> used! You should be able to <em>use the same assembunny interpreter</em> for this as you did there, but with one new instruction:</p>
 112 <p><code>tgl x</code> <em>toggles</em> the instruction <code>x</code> away (pointing at instructions like <code>jnz</code> does: positive means forward; negative means backward):</p>
 113 <ul>
 114 <li>For <em>one-argument</em> instructions, <code>inc</code> becomes <code>dec</code>, and all other one-argument instructions become <code>inc</code>.</li>
 115 <li>For <em>two-argument</em> instructions, <code>jnz</code> becomes <code>cpy</code>, and all other two-instructions become <code>jnz</code>.</li>
 116 <li>The arguments of a toggled instruction are <em>not affected</em>.</li>
 117 <li>If an attempt is made to toggle an instruction outside the program, <em>nothing happens</em>.</li>
 118 <li>If toggling produces an <em>invalid instruction</em> (like <code>cpy 1 2</code>) and an attempt is later made to execute that instruction, <em>skip it instead</em>.</li>
 119 <li>If <code>tgl</code> toggles <em>itself</em> (for example, if <code>a</code> is <code>0</code>, <code>tgl a</code> would target itself and become <code>inc a</code>), the resulting instruction is not executed until the next time it is reached.</li>
 120 </ul>
 121 <p>For example, given this program:</p>
 122 <pre><code>cpy 2 a
 123 tgl a
 124 tgl a
 125 tgl a
 126 cpy 1 a
 127 dec a
 128 dec a
 129 </code></pre>
 130 <ul>
 131 <li><code>cpy 2 a</code> initializes register <code>a</code> to <code>2</code>.</li>
 132 <li>The first <code>tgl a</code> toggles an instruction <code>a</code> (<code>2</code>) away from it, which changes the third <code>tgl a</code> into <code>inc a</code>.</li>
 133 <li>The second <code>tgl a</code> also modifies an instruction <code>2</code> away from it, which changes the <code>cpy 1 a</code> into <code>jnz 1 a</code>.</li>
 134 <li>The fourth line, which is now <code>inc a</code>, increments <code>a</code> to <code>3</code>.</li>
 135 <li>Finally, the fifth line, which is now <code>jnz 1 a</code>, jumps <code>a</code> (<code>3</code>) instructions ahead, skipping the <code>dec a</code> instructions.</li>
 136 </ul>
 137 <p>In this example, the final value in register <code>a</code> is <code>3</code>.</p>
 138 <p>The rest of the electronics seem to place the keypad entry (the number of eggs, <code>7</code>) in register <code>a</code>, run the code, and then send the value left in register <code>a</code> to the safe.</p>
 139 <p><em>What value</em> should be sent to the safe?</p>
 140 </article>
 141 <p>Your puzzle answer was <code>14346</code>.</p><article class="day-desc"><h2>--- Part Two ---</h2><p>The safe doesn't open, but it <em>does</em> make several <span title="SUCH INCORRECT! VERY LOCK! WOW!">angry noises</span> to express its frustration.</p>
 142 <p>You're quite sure your logic is working correctly, so the only other thing is... you check the painting again. As it turns out, colored eggs are still eggs. Now you count <code>12</code>.</p>
 143 <p>As you run the program with this new input, the prototype computer begins to <em>overheat</em>. You wonder what's taking so long, and whether the lack of any instruction more powerful than "add one" has anything to do with it. Don't bunnies usually <em>multiply</em>?</p>
 144 <p>Anyway, <em>what value</em> should actually be sent to the safe?</p>
 145 </article>
 146 <p>Your puzzle answer was <code>479010906</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
 147 <p>At this point, you should <a href="/2016">return to your advent calendar</a> and try another puzzle.</p>
 148 <p>If you still want to see it, you can <a href="23/input" target="_blank">get your puzzle input</a>.</p>
 149 <p>You can also <span class="share">[Share<span class="share-content">on
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