From 6eb34aa6152415e6db96b45456bfaefd242c1b0d Mon Sep 17 00:00:00 2001 From: Brian Chu Date: Tue, 13 Dec 2022 00:34:46 -0800 Subject: solution for day 9 --- solutions/day9.fs | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 solutions/day9.fs (limited to 'solutions') diff --git a/solutions/day9.fs b/solutions/day9.fs new file mode 100644 index 0000000..9c1407f --- /dev/null +++ b/solutions/day9.fs @@ -0,0 +1,39 @@ +namespace Solutions + +module Day9 = + open System.IO + open System.Text.RegularExpressions + open FSharpPlus.Operators + + let parseInstruction line = + let groups = Regex.Match(line, "([LRUD]) (\d+)").Groups + |> Seq.map (fun x -> x.Value) + |> Array.ofSeq + match groups[1], groups[2] with + | "L", count -> List.replicate (int count) (-1, 0) + | "R", count -> List.replicate (int count) (1, 0) + | "U", count -> List.replicate (int count) (0, 1) + | "D", count -> List.replicate (int count) (0, -1) + | _ -> failwith "invalid input" + + let headPositions steps = List.scan (fun (x1, y1) (x2, y2) -> (x1 + x2, y1 + y2)) (0, 0) steps + let instructions = File.ReadLines("inputs/day9.txt") |> Seq.map parseInstruction |> Seq.concat |> List.ofSeq |> headPositions + + let rec followPath (rope: list) (tailSet: Set) (heads: list) = + let touches pointA pointB = abs (fst pointA - fst pointB) <= 1 && abs (snd pointA - snd pointB) <= 1 + let moveTowards head tail = (fst tail + signum (fst head - fst tail), snd tail + signum (snd head - snd tail)) + + if List.length heads = 0 then Set.count tailSet + else + let newHead = List.head heads + let newRope = List.scan (fun head tail -> if touches head tail then tail else moveTowards head tail) newHead (List.tail rope) + followPath newRope (Set.add (List.last newRope) tailSet) (List.tail heads) + + let solution ropeSize = + followPath (List.replicate ropeSize (0, 0)) Set.empty + + let part1 () = instructions + |> solution 2 + + let part2 () = instructions + |> solution 10 \ No newline at end of file -- cgit 1.4.1-2-gfad0 ne.mu.html?h=main'>516read-line.mu.html
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<a href='https://github.com/akkartik/mu/blob/main/516read-line.mu'>https://github.com/akkartik/mu/blob/main/516read-line.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="muComment"># read line from keyboard into stream while also echoing to screen</span>
<span id="L2" class="LineNr"> 2 </span><span class="muComment"># abort on stream overflow</span>
<span id="L3" class="LineNr"> 3 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='516read-line.mu.html#L3'>read-line-from-keyboard</a></span> keyboard: (addr keyboard), out: (addr stream byte), <a href='500fake-screen.mu.html#L16'>screen</a>: (addr <a href='500fake-screen.mu.html#L16'>screen</a>), fg: int, bg: int <span class="Delimiter">{</span>
<span id="L4" class="LineNr"> 4 </span>  <a href='106stream.subx.html#L20'>clear-stream</a> out
<span id="L5" class="LineNr"> 5 </span>  $read-line-from-keyboard:<span class="PreProc">loop</span>: <span class="Delimiter">{</span>
<span id="L6" class="LineNr"> 6 </span>    <a href='500fake-screen.mu.html#L316'>draw-cursor</a> <a href='500fake-screen.mu.html#L16'>screen</a>, <span class="Constant">0x20</span>/space
<span id="L7" class="LineNr"> 7 </span>    <span class="PreProc">var</span> key/eax: byte <span class="Special">&lt;-</span> <a href='102keyboard.subx.html#L21'>read-key</a> keyboard
<span id="L8" class="LineNr"> 8 </span>    compare key, <span class="Constant">0xa</span>/newline
<span id="L9" class="LineNr"> 9 </span>    <span class="PreProc">break-if-=</span>
<span id="L10" class="LineNr">10 </span>    compare key, <span class="Constant">0</span>
<span id="L11" class="LineNr">11 </span>    <span class="PreProc">loop-if-=</span>
<span id="L12" class="LineNr">12 </span>    compare key, <span class="Constant">8</span>/backspace
<span id="L13" class="LineNr">13 </span>    <span class="Delimiter">{</span>
<span id="L14" class="LineNr">14 </span>      <span class="PreProc">break-if-!=</span>
<span id="L15" class="LineNr">15 </span>      <a href='115write-byte.subx.html#L79'>undo-append-byte</a> out
<span id="L16" class="LineNr">16 </span>      <a href='501draw-text.mu.html#L84'>draw-code-point-at-cursor-over-full-screen</a> <a href='500fake-screen.mu.html#L16'>screen</a>, <span class="Constant">0x20</span>/space, fg <span class="Constant">0</span>/bg  <span class="muComment"># clear cursor</span>
<span id="L17" class="LineNr">17 </span>      <a href='501draw-text.mu.html#L3'>move-cursor-left</a> <a href='500fake-screen.mu.html#L16'>screen</a>
<span id="L18" class="LineNr">18 </span>      <a href='501draw-text.mu.html#L3'>move-cursor-left</a> <a href='500fake-screen.mu.html#L16'>screen</a>
<span id="L19" class="LineNr">19 </span>      <a href='501draw-text.mu.html#L84'>draw-code-point-at-cursor-over-full-screen</a> <a href='500fake-screen.mu.html#L16'>screen</a>, <span class="Constant">0x20</span>/space, fg <span class="Constant">0</span>/bg  <span class="muComment"># clear old cursor</span>
<span id="L20" class="LineNr">20 </span>      <a href='501draw-text.mu.html#L3'>move-cursor-left</a> <a href='500fake-screen.mu.html#L16'>screen</a>
<span id="L21" class="LineNr">21 </span>      <span class="PreProc">loop</span> $read-line-from-keyboard:<span class="PreProc">loop</span>
<span id="L22" class="LineNr">22 </span>    <span class="Delimiter">}</span>
<span id="L23" class="LineNr">23 </span>    <span class="PreProc">var</span> key2/eax: int <span class="Special">&lt;-</span> copy key
<span id="L24" class="LineNr">24 </span>    <a href='115write-byte.subx.html#L12'>append-byte</a> out, key2
<span id="L25" class="LineNr">25 </span>    <span class="PreProc">var</span> c/eax: code-point <span class="Special">&lt;-</span> copy key2
<span id="L26" class="LineNr">26 </span>    <a href='501draw-text.mu.html#L84'>draw-code-point-at-cursor-over-full-screen</a> <a href='500fake-screen.mu.html#L16'>screen</a>, c, fg bg
<span id="L27" class="LineNr">27 </span>    <span class="PreProc">loop</span>
<span id="L28" class="LineNr">28 </span>  <span class="Delimiter">}</span>
<span id="L29" class="LineNr">29 </span>  <span class="muComment"># clear cursor</span>
<span id="L30" class="LineNr">30 </span>  <a href='501draw-text.mu.html#L84'>draw-code-point-at-cursor-over-full-screen</a> <a href='500fake-screen.mu.html#L16'>screen</a>, <span class="Constant">0x20</span>/space, fg bg
<span id="L31" class="LineNr">31 </span><span class="Delimiter">}</span>
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