From 6772580e75da036cad5f3b9ea592017c74669a1e Mon Sep 17 00:00:00 2001
From: lub <git@lubiland.de>
Date: Tue, 3 Dec 2019 22:00:04 +0100
Subject: [PATCH] added day 3

---
 03/day03.ps1 | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 03/day03.ps1

diff --git a/03/day03.ps1 b/03/day03.ps1
new file mode 100644
index 0000000..718ed57
--- /dev/null
+++ b/03/day03.ps1
@@ -0,0 +1,103 @@
+param (
+    [Parameter(position = 0)]
+    [array]
+    $Wires = @('R8,U5,L5,D3','U7,R6,D4,L4')
+)
+
+function Trace-Wire {
+    param (
+        [Parameter(Mandatory,
+                   position = 0)]
+        [array]
+        $Steps
+    )
+
+    $path = New-Object -TypeName System.Collections.ArrayList
+
+    #start position is 0,0
+    $position = @{
+        x = 0
+        y = 0
+        distance = $null
+    }
+
+    foreach($step in $Steps) {
+        $direction = $step.Substring(0, 1)
+        $count = $step.Substring(1)
+
+        for($i = 1; $i -le $count; $i++) {
+            switch($direction) {
+                'U' {$position.y += 1}
+                'D' {$position.y -= 1}
+                'R' {$position.x += 1}
+                'L' {$position.x -= 1}
+                Default {Write-Error ('Unkown $direction: {0}' -f $direction)}
+            }
+            $path.Add($position) | Out-Null
+
+            #copy position to prevent adjustment of objects already added to $path
+            $position = $position.Clone()
+        }
+    }
+
+    return $path
+}
+function Compare-Paths {
+    param (
+        [Parameter(Mandatory,
+                   position = 0)]
+        [System.Collections.ArrayList]
+        $PathOne,
+
+        [Parameter(Mandatory,
+                   position = 1)]
+        [System.Collections.ArrayList]
+        $PathTwo
+    )
+
+    $intersections = New-Object -TypeName System.Collections.ArrayList
+
+    foreach($position_one in $path_one) {
+        foreach($position_two in $path_two) {
+            if($position_one.x -eq $position_two.x -and $position_one.y -eq $position_two.y) {
+                $intersections.Add($position_one) | Out-Null
+            }
+        }
+    }
+
+    return $intersections
+}
+function Get-ManhattenDistance {
+    param (
+        [Parameter(Mandatory = $false)]
+        [hashtable]
+        $Source = @{x = 0; y = 0},
+
+        [Parameter(Mandatory,
+                   position = 0)]
+        [hashtable]
+        $Destination
+    )
+
+    $distance  = [math]::Abs($Source.x) + [math]::Abs($Destination.x)
+    $distance += [math]::Abs($Source.y) + [math]::Abs($Destination.y)
+
+    return $distance
+}
+
+# use jobs to trace both wires in parallel
+# (,$arr) prevents ArgumentList from splitting $arr
+$path_one_job = Start-Job ${function:Trace-Wire} -ArgumentList (,$Wires[0].Split(','))
+$path_two_job = Start-Job ${function:Trace-Wire} -ArgumentList (,$Wires[1].Split(','))
+
+# wait for jobs to finish
+$path_one = $path_one_job | Receive-Job -Wait -AutoRemoveJob
+$path_two = $path_two_job | Receive-Job -Wait -AutoRemoveJob
+
+$intersections = Compare-Paths $path_one $path_two
+for($i = 0; $i -lt $intersections.Count; $i++) {
+    $distance = Get-ManhattenDistance -Destination $intersections[$i]
+    $intersections[$i].distance = $distance
+}
+
+($intersections | Sort-Object -Property distance | Select-Object -First 1).distance
\ No newline at end of file