advent-of-code-06.html

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   5 <title>Day 6 - Advent of Code</title>
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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.
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  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.
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  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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 105 <main>
 106 <article class="day-desc"><h2>--- Day 6: Probably a Fire Hazard ---</h2><p>Because your neighbors keep defeating you in the holiday house decorating contest year after year, you've decided to deploy one million lights in a <span title="Hey, be glad I'm not asking for the resistance between two points!">1000x1000 grid</span>.</p>
 107 <p>Furthermore, because you've been especially nice this year, Santa has mailed you instructions on how to display the ideal lighting configuration.</p>
 108 <p>Lights in your grid are numbered from 0 to 999 in each direction; the lights at each corner are at <code>0,0</code>, <code>0,999</code>, <code>999,999</code>, and <code>999,0</code>. The instructions include whether to <code>turn on</code>, <code>turn off</code>, or <code>toggle</code> various inclusive ranges given as coordinate pairs.  Each coordinate pair represents opposite corners of a rectangle, inclusive; a coordinate pair like <code>0,0 through 2,2</code> therefore refers to 9 lights in a 3x3 square.  The lights all start turned off.</code>
 109 <p>To defeat your neighbors this year, all you have to do is set up your lights by doing the instructions Santa sent you in order.</p>
 110 <p>For example:</p>
 111 <ul>
 112 <li><code>turn on 0,0 through 999,999</code> would turn on (or leave on) every light.</li>
 113 <li><code>toggle 0,0 through 999,0</code> would toggle the first line of 1000 lights, turning off the ones that were on, and turning on the ones that were off.</li>
 114 <li><code>turn off 499,499 through 500,500</code> would turn off (or leave off) the middle four lights.</li>
 115 </ul>
 116 <p>After following the instructions, <em>how many lights are lit</em>?</p>
 117 </article>
 118 <p>Your puzzle answer was <code>569999</code>.</p><article class="day-desc"><h2>--- Part Two ---</h2><p>You just finish implementing your winning light pattern when you realize you mistranslated Santa's message from Ancient Nordic Elvish.</p>
 119 <p>The light grid you bought actually has individual brightness controls; each light can have a brightness of zero or more.  The lights all start at zero.</p>
 120 <p>The phrase <code>turn on</code> actually means that you should increase the brightness of those lights by <code>1</code>.</p>
 121 <p>The phrase <code>turn off</code> actually means that you should decrease the brightness of those lights by <code>1</code>, to a minimum of zero.</p>
 122 <p>The phrase <code>toggle</code> actually means that you should increase the brightness of those lights by <code>2</code>.</p>
 123 <p>What is the <em>total brightness</em> of all lights combined after following Santa's instructions?</p>
 124 <p>For example:</p>
 125 <ul>
 126 <li><code>turn on 0,0 through 0,0</code> would increase the total brightness by <code>1</code>.</li>
 127 <li><code>toggle 0,0 through 999,999</code> would increase the total brightness by <code>2000000</code>.</li>
 128 </ul>
 129 </article>
 130 <p>Your puzzle answer was <code>17836115</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
 131 <p>At this point, you should <a href="/">return to your advent calendar</a> and try another puzzle.</p>
 132 <p>If you still want to see it, you can <a href="/day/6/input" target="_blank">get your puzzle input</a>.</p>
 133 <p>You can also <span class="share">[Share<span class="share-content">on
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 137 ></span>]</span>
 138  this puzzle.</p>
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