advent-of-code-11.html

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  15 Oh, hello!  Funny seeing you here.
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  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.  You do risk spoiling a few
  19 surprises for yourself, though.  Best to play the normal way and discover
  20 everything as it was intended, I think.  The best surprises don't even appear
  21 in the source until you unlock them for real.
  22
  23 Please be careful with automated requests; I'm not Google, and I can only take
  24 so much traffic.  Please be considerate so that everyone gets to play.
  25
  26 If you're curious about how Advent of Code works, it's running on some custom
  27 Perl code. Other than a few integrations (auth, analytics, ads, social media),
  28 I built the whole thing myself, including the design, animations, prose, and
  29 all of the puzzles.
  30
  31 The puzzles probably took the longest; the easiest ones were around 45 minutes
  32 each, but the harder ones took 2-3 hours, some even longer than that. A lot of
  33 effort went into building this thing - I hope you're enjoying playing it as
  34 much as I enjoyed making it for you!
  35
  36 If you'd like to hang out, I'm @ericwastl on Twitter.
  37
  38 - Eric Wastl
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  89 -->
  90 <body>
  91 <header><h1><a href="/">Advent of Code</a></h1><div class="user">Neil Smith <span class="star-count">26*</span></div><nav><ul><li><a href="/about">[About]</a></li><li><a href="/stats">[Stats]</a></li><li><a href="/leaderboard">[Leaderboard]</a></li><li><a href="/settings">[Settings]</a></li><li><a href="/auth/logout">[Log out]</a></li></ul></nav></header>
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 106 <article class="day-desc"><h2>--- Day 11: Corporate Policy ---</h2><p>Santa's previous password expired, and he needs help choosing a new one.</p>
 107 <p>To help him remember his new password after the old one expires, Santa has devised a method of coming up with a password based on the previous one.  Corporate policy dictates that passwords must be exactly eight lowercase letters (for security reasons), so he finds his new password by <em>incrementing</em> his old password string repeatedly until it is valid.</p>
 108 <p>Incrementing is just like counting with numbers: <code>xx</code>, <code>xy</code>, <code>xz</code>, <code>ya</code>, <code>yb</code>, and so on. Increase the rightmost letter one step; if it was <code>z</code>, it wraps around to <code>a</code>, and repeat with the next letter to the left until one doesn't wrap around.</p>
 109 <p>Unfortunately for Santa, a new Security-Elf recently started, and he has imposed some additional password requirements:</p>
 110 <ul>
 111 <li>Passwords must include one increasing straight of at least three letters, like <code>abc</code>, <code>bcd</code>, <code>cde</code>, and so on, up to <code>xyz</code>. They cannot skip letters; <code>abd</code> doesn't count.</li>
 112 <li>Passwords may not contain the letters <code>i</code>, <code>o</code>, or <code>l</code>, as these letters can be mistaken for other characters and are therefore confusing.</li>
 113 <li>Passwords must contain at least two different, non-overlapping pairs of letters, like <code>aa</code>, <code>bb</code>, or <code>zz</code>.</li>
 114 </ul>
 115 <p>For example:</p>
 116 <ul>
 117 <li><code>hijklmmn</code> meets the first requirement (because it contains the straight <code>hij</code>) but fails the second requirement requirement (because it contains <code>i</code> and <code>l</code>).</li>
 118 <li><code>abbceffg</code> meets the third requirement (because it repeats <code>bb</code> and <code>ff</code>) but fails the first requirement.</li>
 119 <li><code>abbcegjk</code> fails the third requirement, because it only has one double letter (<code>bb</code>).</li>
 120 <li>The next password after <code>abcdefgh</code> is <code>abcdffaa</code>.</li>
 121 <li>The next password after <code>ghijklmn</code> is <code>ghjaabcc</code>, because you eventually skip all the passwords that start with <code>ghi...</code>, since <code>i</code> is not allowed.</li>
 122 </ul>
 123 <p>Given Santa's current password (your puzzle input), what should his <em>next password</em> be?</p>
 124 </article>
 125 <p>Your puzzle answer was <code>hxbxxyzz</code>.</p><article class="day-desc"><h2>--- Part Two ---</h2><p>Santa's password <span title="The corporate policy says your password expires after 12 seconds.  For security.">expired again</span>.  What's the next one?</p>
 126 </article>
 127 <p>Your puzzle answer was <code>hxcaabcc</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
 128 <p>At this point, you should <a href="/">return to your advent calendar</a> and try another puzzle.</p>
 129 <p>Your puzzle input was <code class="puzzle-input">hxbxwxba</code>.</p>
 130 <p>You can also <span class="share">[Share<span class="share-content">on
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 132   <a href="https://plus.google.com/share?url=http%3A%2F%2Fadventofcode%2Ecom%2Fday%2F11" target="_blank">Google+</a>
 133   <a href="http://www.reddit.com/submit?url=http%3A%2F%2Fadventofcode%2Ecom%2Fday%2F11&amp;title=I%27ve+completed+%22Corporate+Policy%22+%2D+Day+11+%2D+Advent+of+Code" target="_blank">Reddit</a
 134 ></span>]</span>
 135  this puzzle.</p>
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