From aa62b0c47489864f3c4bee436b56617207c89f4a Mon Sep 17 00:00:00 2001
From: Greg Burri <greg.burri@gmail.com>
Date: Sat, 23 Dec 2017 22:38:23 +0100
Subject: [PATCH] Day 23

---
 AdventOfCode2017/AdventOfCode2017.fsproj |  8 ++-
 AdventOfCode2017/Day22.fs                |  4 +-
 AdventOfCode2017/Day23.fs                | 68 ++++++++++++++++++++++++
 AdventOfCode2017/Program.fs              |  5 ++
 4 files changed, 81 insertions(+), 4 deletions(-)
 create mode 100644 AdventOfCode2017/Day23.fs

diff --git a/AdventOfCode2017/AdventOfCode2017.fsproj b/AdventOfCode2017/AdventOfCode2017.fsproj
index 1e530b7..0faadbe 100644
--- a/AdventOfCode2017/AdventOfCode2017.fsproj
+++ b/AdventOfCode2017/AdventOfCode2017.fsproj
@@ -25,7 +25,7 @@
     <PlatformTarget>AnyCPU</PlatformTarget>
     <DocumentationFile>bin\$(Configuration)\$(AssemblyName).XML</DocumentationFile>
     <Prefer32Bit>true</Prefer32Bit>
-    <StartArguments>22</StartArguments>
+    <StartArguments>23</StartArguments>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
@@ -37,7 +37,7 @@
     <PlatformTarget>AnyCPU</PlatformTarget>
     <DocumentationFile>bin\$(Configuration)\$(AssemblyName).XML</DocumentationFile>
     <Prefer32Bit>true</Prefer32Bit>
-    <StartArguments>22</StartArguments>
+    <StartArguments>23</StartArguments>
   </PropertyGroup>
   <PropertyGroup>
     <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">11</MinimumVisualStudioVersion>
@@ -81,6 +81,7 @@
     <Compile Include="Day20.fs" />
     <Compile Include="Day21.fs" />
     <Compile Include="Day22.fs" />
+    <Compile Include="Day23.fs" />
     <Compile Include="Program.fs" />
     <None Include="App.config" />
     <Content Include="Data\day01.input">
@@ -149,6 +150,9 @@
     <Content Include="Data\day22.input">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Data\day23.input">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
diff --git a/AdventOfCode2017/Day22.fs b/AdventOfCode2017/Day22.fs
index 1de16e8..532c465 100644
--- a/AdventOfCode2017/Day22.fs
+++ b/AdventOfCode2017/Day22.fs
@@ -13,9 +13,9 @@ let parseInput (lines : string[]) : M =
                 m.Add ((x - lines.[y].Length / 2, -y + lines.Length / 2), Infected)
     m
 
-let reverse (dx, dy) = -dx, -dy
+let inline reverse (dx, dy) = -dx, -dy
 let turnRight = function 1, 0 -> 0, -1 | 0, 1 ->  1, 0 | -1, 0 -> 0, 1  | _ -> -1, 0
-let turnLeft  = turnRight >> reverse
+let turnLeft = turnRight >> reverse
 
 let infection (rule : CellState -> CellState * ((int * int) -> (int * int))) (nbIterations : int) (m : M) : int =
     let rec burst (x, y) d n becomeInfected =
diff --git a/AdventOfCode2017/Day23.fs b/AdventOfCode2017/Day23.fs
new file mode 100644
index 0000000..34cde9a
--- /dev/null
+++ b/AdventOfCode2017/Day23.fs
@@ -0,0 +1,68 @@
+module AdventOfCode2017.Day23
+
+open System
+
+type From =
+    | FromReg of char
+    | FromValue of int64
+
+type Instruction =
+    | Set of char * From
+    | Sub of char * From
+    | Mul of char * From
+    | Jump of From * From
+
+let parseInput (lines : string[]) : Instruction[] =
+    let readFrom (str : string) = if Char.IsLetter str.[0] then FromReg str.[0] else FromValue (int64 str)
+    lines
+    |> Array.map (
+        fun line ->
+            match line.Split ' ' with
+            | [| "set"; reg; v |] -> Set (reg.[0], readFrom v)
+            | [| "sub"; reg; v |] -> Sub (reg.[0], readFrom v)
+            | [| "mul"; reg; v |] -> Mul (reg.[0], readFrom v)
+            | [| "jnz"; v1; v2 |] -> Jump (readFrom v1, readFrom v2)
+            | _ -> failwithf "Can't parse line: %s" line
+    )
+
+type Register = Map<char, int64>
+
+let run (instructions : Instruction[]) : int =
+    let rec exec (register : Register) (cursor : int) (nbMul : int) : int  =
+        let get = function FromReg reg -> register |> Map.tryFind reg |> Option.defaultValue 0L | FromValue v -> v
+        let set (reg : char) (v : int64) = register |> Map.add reg v
+
+        if cursor < 0 || cursor >= instructions.Length then
+            nbMul
+        else
+            match instructions.[cursor] with
+            | Set (reg, from) -> exec (set reg (get from)) (cursor + 1) nbMul
+            | Sub (reg, from) -> exec (set reg (get (FromReg reg) - get from)) (cursor + 1) nbMul
+            | Mul (reg, from) -> exec (set reg (get (FromReg reg) * get from)) (cursor + 1) (nbMul + 1)
+            | Jump (from1, from2) -> exec register (cursor + if get from1 <> 0L then get from2 |> int else 1) nbMul
+    exec Map.empty 0 0
+
+let debug () =
+    let mutable b = 99 * 100 + 100000
+    let c = b + 17000
+    let mutable h = 0
+
+    let mutable ``end`` = false
+    while not ``end`` do
+        let mutable f = 1
+        let mutable d = 2
+        let mutable loop = true
+        while loop do
+            f <- if b % d = 0 then 0 else f
+            d <- d + 1
+            loop <- d <> b
+
+        if f = 0 then
+            h <- h + 1
+
+        ``end`` <- b = c
+
+        b <- b + 17
+    h
+
+
diff --git a/AdventOfCode2017/Program.fs b/AdventOfCode2017/Program.fs
index 379137e..781fb24 100644
--- a/AdventOfCode2017/Program.fs
+++ b/AdventOfCode2017/Program.fs
@@ -100,6 +100,10 @@ let day22 () =
     let input = File.ReadAllLines "Data/day22.input" |> Day22.parseInput
     sprintf "part1 = %A, part2 = %A" (Day22.infection1 input) (Day22.infection2 input)
 
+let day23 () =
+    let input = File.ReadAllLines "Data/day23.input" |> Day23.parseInput
+    sprintf "part1 = %A, part2 = %A" (Day23.run input) (Day23.debug ())
+
 let doDay (n : int) =
     let sw = Diagnostics.Stopwatch ()
     sw.Start ()
@@ -127,6 +131,7 @@ let doDay (n : int) =
         | 20 -> day20 ()
         | 21 -> day21 ()
         | 22 -> day22 ()
+        | 23 -> day23 ()
         | _ -> raise <| NotImplementedException ()
     printfn "Result of day %i: %s (time : %i ms)" n result sw.ElapsedMilliseconds
 
-- 
2.45.2