--- /dev/null
+# Extensionless files
+*
+!/**/
+!*.*
+
+# Haskell bits
+dist
+dist-*
+cabal-dev
+*.o
+*.hi
+*.chi
+*.chs.h
+*.dyn_o
+*.dyn_hi
+.hpc
+.hsenv
+.cabal-sandbox/
+cabal.sandbox.config
+*.prof
+*.aux
+*.hp
+*.eventlog
+.stack-work/
+cabal.project.local
+.HTF/
+
+# A semelance of purity!
+# IPython
+.ipynb*
+*.ipynb
+
+# Sublime text
+*.sublime-workspace
+
+# Logs
+*.log
+
--- /dev/null
+<p><link rel="stylesheet" href="modest.css"></link></p>
+<h1 id="advent-of-code-2016">Advent of Code 2016</h1>
+<p>Code to solve the <a href="http://adventofcode.com/2016/">Advent of Code</a> puzzles. This year, I'm trying to use the puzzles as a prompt to learn <a href="https://wiki.haskell.org/Haskell">Haskell</a>.</p>
+<p><a href="http://learnyouahaskell.com/chapters">Learn you a Haskell</a>, <a href="https://www.haskell.org/tutorial/index.html">Introduction to Haskell 98</a>, and <a href="https://hackage.haskell.org/">Hackage</a> are good resources.</p>
+<p>I'm using the basic Haskell Platform installation (install with</p>
+<pre><code>$ sudo aptitude install haskell-platform</code></pre>
+<p>).</p>
+<p>Compile the code with</p>
+<pre><code>ghc -o advent01 advent01.hs</code></pre>
+<p>then run it as</p>
+<pre><code>advent01</code></pre>
+<p>(Using the <a href="https://github.com/markdowncss/modest">Modest styles</a>.)</p>
--- /dev/null
+---
+title: "Advent of Code 2016"
+output:
+ html_document:
+ css: modest.css
+---
+<link rel="stylesheet" href="modest.css"></link>
+
+# Advent of Code 2016
+
+Code to solve the [Advent of Code](http://adventofcode.com/2016/) puzzles. This year, I'm trying to use the puzzles as a prompt to learn [Haskell](https://wiki.haskell.org/Haskell).
+
+[Learn you a Haskell](http://learnyouahaskell.com/chapters), [Introduction to Haskell 98](https://www.haskell.org/tutorial/index.html), and [Hackage](https://hackage.haskell.org/) are good resources.
+
+I'm using the basic Haskell Platform installation (install with
+```
+$ sudo aptitude install haskell-platform
+```
+).
+
+Compile the code with
+```
+ghc -o advent01 advent01.hs
+```
+
+then run it as
+```
+advent01
+```
+
+(Using the [Modest styles](https://github.com/markdowncss/modest).)
\ No newline at end of file
--- /dev/null
+import Data.List (sort)
+import Data.List.Split (splitOn)
+
+-- turn direction, number of steps
+data Step = Step Char Int deriving (Show)
+
+data Direction = North | East | South | West
+ deriving (Enum, Show, Bounded, Eq)
+
+-- direction, easting, northing
+data Position = Position Direction Int Int deriving (Show)
+-- Two positions are the same if they're in the same place,
+-- regardless of facing
+instance Eq Position where
+ Position _ e n == Position _ e' n' = e == e' && n == n'
+
+main :: IO ()
+main = do
+ instructions <- readFile "advent01.txt"
+ part1 instructions
+ part2 instructions
+
+part1 :: String -> IO ()
+part1 instructions = do
+ let answer = finalDistance $ last $ stepsFromStart $ steps instructions
+ print answer
+
+part2 :: String -> IO ()
+part2 instructions = do
+ let visited = finalDistance $ firstRepeat $ stepsFromStart $ expandSteps $ steps instructions
+ print visited
+
+
+-- Extract the steps from the input string.
+steps :: String -> [Step]
+steps s = map readStep $ splitOn ", " s
+ where readStep (d:l) = Step d (read l)
+
+-- Take steps from the starting position
+stepsFromStart :: [Step] -> [Position]
+stepsFromStart = takeSteps (Position North 0 0)
+
+-- Calculate manhattan distance from start to this state
+finalDistance :: Position -> Int
+finalDistance (Position _ e n) = (abs e) + (abs n)
+
+-- For part 2: convert one step of many spaces to many steps of one space each
+expandSteps :: [Step] -> [Step]
+expandSteps =
+ concatMap expandStep
+ where expandStep (Step dir d) = (Step dir 1) : replicate (d - 1) (Step 'S' 1)
+
+-- Execute a series of steps, keeping track of the positions after each step
+takeSteps :: Position -> [Step] -> [Position]
+takeSteps pos steps = scanl move pos steps
+
+-- Make one move, by updating direction then position
+move :: Position -> Step -> Position
+move (Position facing easting northing)
+ (Step turnInstr distance) =
+ Position facing' easting' northing'
+ where facing' = turn turnInstr facing
+ (easting', northing') = takeStep facing' distance easting northing
+
+-- Turn right, left, or straight
+turn :: Char -> Direction -> Direction
+turn 'R' direction = turnCW direction
+turn 'L' direction = turnACW direction
+turn 'S' direction = direction
+
+-- Move in the current direction
+takeStep :: Direction -> Int -> Int -> Int -> (Int, Int)
+takeStep North d e n = (e, n+d)
+takeStep South d e n = (e, n-d)
+takeStep West d e n = (e-d, n)
+takeStep East d e n = (e+d, n)
+
+
+-- | a `succ` that wraps
+turnCW :: (Bounded a, Enum a, Eq a) => a -> a
+turnCW dir | dir == maxBound = minBound
+ | otherwise = succ dir
+
+-- | a `pred` that wraps
+turnACW :: (Bounded a, Enum a, Eq a) => a -> a
+turnACW dir | dir == minBound = maxBound
+ | otherwise = pred dir
+
+-- All the prefixes of a list of items
+prefixes = scanl addTerm []
+ where addTerm ps t = ps ++ [t]
+
+-- The first item that exists in a prefix of the list to that point
+firstRepeat positions =
+ last $ head $ dropWhile (\p -> (last p) `notElem` (tail $ reverse p))
+ (tail $ prefixes positions)
--- /dev/null
+R2, L3, R2, R4, L2, L1, R2, R4, R1, L4, L5, R5, R5, R2, R2, R1, L2, L3, L2, L1, R3, L5, R187, R1, R4, L1, R5, L3, L4, R50, L4, R2, R70, L3, L2, R4, R3, R194, L3, L4, L4, L3, L4, R4, R5, L1, L5, L4, R1, L2, R4, L5, L3, R4, L5, L5, R5, R3, R5, L2, L4, R4, L1, R3, R1, L1, L2, R2, R2, L3, R3, R2, R5, R2, R5, L3, R2, L5, R1, R2, R2, L4, L5, L1, L4, R4, R3, R1, R2, L1, L2, R4, R5, L2, R3, L4, L5, L5, L4, R4, L2, R1, R1, L2, L3, L2, R2, L4, R3, R2, L1, L3, L2, L4, L4, R2, L3, L3, R2, L4, L3, R4, R3, L2, L1, L4, R4, R2, L4, L4, L5, L1, R2, L5, L2, L3, R2, L2
\ No newline at end of file
--- /dev/null
+<!DOCTYPE html>
+<html lang="en-us">
+<head>
+<meta charset="utf-8"/>
+<title>Day 1 - Advent of Code 2016</title>
+<!--[if lt IE 9]><script src="/static/html5.js"></script><![endif]-->
+<link href='//fonts.googleapis.com/css?family=Source+Code+Pro:300&subset=latin,latin-ext' rel='stylesheet' type='text/css'>
+<link rel="stylesheet" type="text/css" href="/static/style.css?6"/>
+<link rel="shortcut icon" href="/favicon.ico?2"/>
+</head><!--
+
+
+
+
+Oh, hello! Funny seeing you here.
+
+I appreciate your enthusiasm, but you aren't going to find much down here.
+There certainly aren't clues to any of the puzzles. The best surprises don't
+even appear in the source until you unlock them for real.
+
+Please be careful with automated requests; I'm not Google, and I can only take
+so much traffic. Please be considerate so that everyone gets to play.
+
+If you're curious about how Advent of Code works, it's running on some custom
+Perl code. Other than a few integrations (auth, analytics, ads, social media),
+I built the whole thing myself, including the design, animations, prose, and
+all of the puzzles.
+
+The puzzles probably took the longest; the easiest ones were around 45 minutes
+each, but the harder ones took 2-3 hours, and a few even longer than that. A
+lot of effort went into building this thing - I hope you're enjoying playing it
+as much as I enjoyed making it for you!
+
+If you'd like to hang out, I'm @ericwastl on Twitter.
+
+- Eric Wastl
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+-->
+<body>
+<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="star-count">2*</span></div></div><div><h1 class="title-event"> <span class="title-event-wrap">y(</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>
+
+<div id="sidebar">
+<div id="sponsor"><div class="quiet">Our <a href="/2016/sponsors">sponsors</a> help make AoC possible:</div><p><a href="https://www.detroitlabs.com/careers" target="_blank" onclick="if(ga)ga('send','event','sponsor','click',this.href);">Detroit Labs</a> - Build beautiful mobile apps.</p></div>
+<div id="ad">
+<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
+<!-- Advent of Code Wide Skyscraper -->
+<ins class="adsbygoogle"
+ style="display:inline-block;width:160px;height:600px"
+ data-ad-client="ca-pub-9420604735624631"
+ data-ad-slot="8014013294"></ins>
+<script>
+(adsbygoogle = window.adsbygoogle || []).push({});
+</script>
+</div><!--/ad-->
+</div><!--/sidebar-->
+
+<main>
+<article class="day-desc"><h2>--- Day 1: No Time for a Taxicab ---</h2><p>Santa's sleigh uses a <span title="An atomic clock is too inaccurate; he might end up in a wall!">very high-precision clock</span> to guide its movements, and the clock's oscillator is regulated by stars. Unfortunately, the stars have been stolen... by the Easter Bunny. To save Christmas, Santa needs you to retrieve all <em class="star">fifty stars</em> by December 25th.</p>
+<p>Collect stars by solving puzzles. Two puzzles will be made available on each day in the advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants <em class="star">one star</em>. Good luck!</p>
+<p>You're airdropped near <em>Easter Bunny Headquarters</em> in a city somewhere. "Near", unfortunately, is as close as you can get - the instructions on the Easter Bunny Recruiting Document the Elves intercepted start here, and nobody had time to work them out further.</p>
+<p>The Document indicates that you should start at the given coordinates (where you just landed) and face North. Then, follow the provided sequence: either turn left (<code>L</code>) or right (<code>R</code>) 90 degrees, then walk forward the given number of blocks, ending at a new intersection.</p>
+<p>There's no time to follow such ridiculous instructions on foot, though, so you take a moment and work out the destination. Given that you can only walk on the <a href="https://en.wikipedia.org/wiki/Taxicab_geometry">street grid of the city</a>, how far is the shortest path to the destination?</p>
+<p>For example:</p>
+<ul>
+<li>Following <code>R2, L3</code> leaves you <code>2</code> blocks East and <code>3</code> blocks North, or <code>5</code> blocks away.</li>
+<li><code>R2, R2, R2</code> leaves you <code>2</code> blocks due South of your starting position, which is <code>2</code> blocks away.</li>
+<li><code>R5, L5, R5, R3</code> leaves you <code>12</code> blocks away.</li>
+</ul>
+<p><em>How many blocks away</em> is Easter Bunny HQ?</p>
+</article>
+<p>Your puzzle answer was <code>246</code>.</p><article class="day-desc"><h2>--- Part Two ---</h2><p>Then, you notice the instructions continue on the back of the Recruiting Document. Easter Bunny HQ is actually at the first location you visit twice.</p>
+<p>For example, if your instructions are <code>R8, R4, R4, R8</code>, the first location you visit twice is <code>4</code> blocks away, due East.</p>
+<p>How many blocks away is the <em>first location you visit twice</em>?</p>
+</article>
+<p>Your puzzle answer was <code>124</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
+<p>At this point, you should <a href="/2016">return to your advent calendar</a> and try another puzzle.</p>
+<p>If you still want to see it, you can <a href="1/input" target="_blank">get your puzzle input</a>.</p>
+<p>You can also <span class="share">[Share<span class="share-content">on
+ <a href="https://twitter.com/intent/tweet?text=I%27ve+completed+%22No+Time+for+a+Taxicab%22+%2D+Day+1+%2D+Advent+of+Code+2016&url=http%3A%2F%2Fadventofcode%2Ecom%2F2016%2Fday%2F1&related=ericwastl&hashtags=AdventOfCode" target="_blank">Twitter</a>
+ <a href="https://plus.google.com/share?url=http%3A%2F%2Fadventofcode%2Ecom%2F2016%2Fday%2F1" target="_blank">Google+</a>
+ <a href="http://www.reddit.com/submit?url=http%3A%2F%2Fadventofcode%2Ecom%2F2016%2Fday%2F1&title=I%27ve+completed+%22No+Time+for+a+Taxicab%22+%2D+Day+1+%2D+Advent+of+Code+2016" target="_blank">Reddit</a
+></span>]</span> this puzzle.</p>
+</main>
+
+<!-- ga -->
+<script>
+(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
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+ga('create', 'UA-69522494-1', 'auto');
+ga('send', 'pageview');
+</script>
+<!-- /ga -->
+</body>
+</html>
\ No newline at end of file
--- /dev/null
+@media print {
+ *,
+ *:before,
+ *:after {
+ background: transparent !important;
+ color: #000 !important;
+ box-shadow: none !important;
+ text-shadow: none !important;
+ }
+
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+ text-decoration: underline;
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+ content: " (" attr(title) ")";
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+ max-width: 100% !important;
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+
+img,
+canvas,
+iframe,
+video,
+svg,
+select,
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+ max-width: 100%;
+}
+
+@import url(http://fonts.googleapis.com/css?family=Open+Sans+Condensed:300,300italic,700);
+
+@import url(http://fonts.googleapis.com/css?family=Arimo:700,700italic);
+
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+}
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+
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+ padding: 1rem;
+}
+
+pre,
+code {
+ background-color: #fafafa;
+}
\ No newline at end of file
projects / advent-of-code-16.git / commitdiff