From 1d69a977ff3fab545b88add198f637ac2d0c9bd9 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gr=C3=A9gory=20Burri?= <gregory.burri@matisa.ch>
Date: Fri, 7 Dec 2018 09:42:05 +0100
Subject: [PATCH] Day 6.

---
 AdventOfCode2018.fsproj |  4 +++
 Day06.fs                | 65 +++++++++++++++++++++++++++++++++++++++++
 Program.fs              |  5 ++++
 Tests/Day06 tests.fs    | 29 ++++++++++++++++++
 Tests/Tests.fsproj      |  1 +
 5 files changed, 104 insertions(+)
 create mode 100644 Day06.fs
 create mode 100644 Tests/Day06 tests.fs

diff --git a/AdventOfCode2018.fsproj b/AdventOfCode2018.fsproj
index 4a31bd3..7026dc3 100644
--- a/AdventOfCode2018.fsproj
+++ b/AdventOfCode2018.fsproj
@@ -4,12 +4,16 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="Day06.fs" />
     <Compile Include="Day05.fs" />
     <Compile Include="Day04.fs" />
     <Compile Include="Day03.fs" />
     <Compile Include="Day02.fs" />
     <Compile Include="Day01.fs" />
     <Compile Include="Program.fs" />
+    <Content Include="Data/day06.input">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="Data/day05.input">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
diff --git a/Day06.fs b/Day06.fs
new file mode 100644
index 0000000..683f373
--- /dev/null
+++ b/Day06.fs
@@ -0,0 +1,65 @@
+module AdventOfCode2018.Day06
+
+open System
+
+type Coords = { X : int; Y : int }
+    with
+        member this.Distance (coords : Coords) : int =
+            abs (coords.X - this.X) + abs (coords.Y - this.Y)
+
+        static member Parse (str : string) =
+            let coords = str.Split ','
+            { X = int coords.[0]; Y = int coords.[1] }
+
+let parseInput (str : string) : Coords array =
+    str.Split ([| '\r'; '\n'; |], StringSplitOptions.RemoveEmptyEntries)
+    |> Array.map Coords.Parse
+
+let getLargestArea (coords : Coords array) : int =
+    let coordsX = coords |> Array.map (fun coords -> coords.X)
+    let coordsY = coords |> Array.map (fun coords -> coords.Y)
+    let minX, minY, maxX, maxY = coordsX |> Array.min, coordsY |> Array.min, coordsX |> Array.max, coordsY |> Array.max
+
+    let areas = Array.zeroCreate coords.Length
+
+    for x = minX to maxX do
+        for y = minY to maxY do
+            let pos = { X = x; Y = y }
+            let mutable nearest = -1
+            let mutable distance = Int32.MaxValue
+            let mutable equalDistance = false
+
+            for i = 0 to coords.Length - 1 do
+                let distance' = pos.Distance coords.[i]
+                if distance' = distance then
+                    equalDistance <- true
+                if distance' < distance then
+                    nearest <- i
+                    distance <- distance'
+                    equalDistance <- false
+
+            if not equalDistance then
+                if x = minX || y = minY || x = maxX || y = maxY then
+                    areas.[nearest] <- -1
+                elif areas.[nearest] <> -1 then
+                    areas.[nearest] <- areas.[nearest] + 1
+
+    areas |> Array.max
+
+let getAreaWithTotalDistanceLessThan (total : int) (coords : Coords array) : int =
+    let coordsX = coords |> Array.map (fun coords -> coords.X)
+    let coordsY = coords |> Array.map (fun coords -> coords.Y)
+    let minX, minY, maxX, maxY = coordsX |> Array.min, coordsY |> Array.min, coordsX |> Array.max, coordsY |> Array.max
+
+    let mutable area = 0
+
+    for x = minX to maxX do
+        for y = minY to maxY do
+            let pos = { X = x; Y = y }
+            let mutable totalDistance = 0
+            for i = 0 to coords.Length - 1 do
+                totalDistance <- totalDistance + pos.Distance coords.[i]
+            if totalDistance < total then
+                area <- area + 1
+
+    area
\ No newline at end of file
diff --git a/Program.fs b/Program.fs
index fb433b7..fcb5fc1 100644
--- a/Program.fs
+++ b/Program.fs
@@ -25,6 +25,10 @@ let day05 () =
     let reduced = (File.ReadAllText "Data/day05.input").Trim () |> List.ofSeq |> Day05.reduce
     sprintf "part1 = %A, part2 = %A" reduced.Length (Day05.findShortestPolymer reduced).Length
 
+let day06 () =
+    let coords = File.ReadAllText "Data/day06.input" |> Day06.parseInput
+    sprintf "part1 = %A, part2 = %A" (Day06.getLargestArea coords) (Day06.getAreaWithTotalDistanceLessThan 10000 coords)
+
 let days : Map<int, unit -> string> =
     [
         1, day01
@@ -32,6 +36,7 @@ let days : Map<int, unit -> string> =
         3, day03
         4, day04
         5, day05
+        6, day06
     ] |> Map.ofList
 
 let doDay (n : int) =
diff --git a/Tests/Day06 tests.fs b/Tests/Day06 tests.fs
new file mode 100644
index 0000000..38e1df5
--- /dev/null
+++ b/Tests/Day06 tests.fs	
@@ -0,0 +1,29 @@
+namespace AdventOfCode2018.Tests
+
+open System
+
+open Xunit
+open Xunit.Abstractions
+open Swensen.Unquote
+
+open AdventOfCode2018
+
+type ``Day06 tests`` (output : ITestOutputHelper) =
+    let input =
+        """1, 1
+           1, 6
+           8, 3
+           3, 4
+           5, 5
+           8, 9"""
+
+    [<Fact>]
+    let ``(Part1) From web page`` () =
+        let coords = Day06.parseInput input
+        Day06.getLargestArea coords =! 17
+
+    [<Fact>]
+    let ``(Part2) From web page`` () =
+        let coords = Day06.parseInput input
+        Day06.getAreaWithTotalDistanceLessThan 32 coords =! 16
+
diff --git a/Tests/Tests.fsproj b/Tests/Tests.fsproj
index a7712db..0042788 100644
--- a/Tests/Tests.fsproj
+++ b/Tests/Tests.fsproj
@@ -6,6 +6,7 @@
     <ProjectReference Include="..\AdventOfCode2018.fsproj" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Day06 tests.fs" />
     <Compile Include="Day05 tests.fs" />
     <Compile Include="Day04 tests.fs" />
     <Compile Include="Day03 tests.fs" />
-- 
2.45.2