From 44656a253cb5c410b5d1aed0c84174f910e479ff Mon Sep 17 00:00:00 2001
From: PaddyKe <34421580+PaddyKe@users.noreply.github.com>
Date: Sun, 4 Oct 2020 14:46:04 +0200
Subject: [PATCH 1/2] added GrahamScan in PowerShell

---
 .../code/powershell/GrahamScan.ps1            | 48 +++++++++++++++++++
 contents/graham_scan/graham_scan.md           |  6 +++
 2 files changed, 54 insertions(+)
 create mode 100644 contents/graham_scan/code/powershell/GrahamScan.ps1

diff --git a/contents/graham_scan/code/powershell/GrahamScan.ps1 b/contents/graham_scan/code/powershell/GrahamScan.ps1
new file mode 100644
index 000000000..4ea89225c
--- /dev/null
+++ b/contents/graham_scan/code/powershell/GrahamScan.ps1
@@ -0,0 +1,48 @@
+function New-Point($x, $y) {
+    return New-Object -TypeName PSObject -Property @{X = [int]$x; Y = [int]$y}
+}
+
+function CounterClockWise($p1, $p2, $p3) {
+    return (($p3.Y - $p1.Y) * ($p2.X - $p1.X)) -ge (($p2.Y - $p1.Y) * ($p3.X - $p1.X))
+}
+
+function Graham-Scan([System.Collections.ArrayList] $gift) {
+    [System.Collections.ArrayList]$gift = $gift | Get-Unique -AsString
+    $start = $gift | Sort-Object -Property Y | Select-Object -First 1
+    $gift.Remove($start)
+
+    $s = $gift | Sort-Object -Property {[Math]::Atan2($_.Y - $start.Y, $_.X - $start.X)}
+    [System.Collections.ArrayList]$hull = @($start, $s[0], $s[1])
+
+    $s | Select-Object -Skip 2 | ForEach-Object {
+        while (-not (CounterClockWise $hull[-2] $hull[-1] $_)) {
+            $hull.RemoveAt($hull.Count - 1)
+        }
+        $hull.Add($_) | Out-Null
+    }
+
+    return $hull
+}
+
+
+$testGift = @(
+        (New-Point -5 2)
+        (New-Point 5 7)
+        (New-Point -6 -12)
+        (New-Point -14 -14)
+        (New-Point 9 9)
+        (New-Point -1 -1)
+        (New-Point -10 11)
+        (New-Point -6 15)
+        (New-Point -6 -8)
+        (New-Point 15 -9)
+        (New-Point 7 -7)
+        (New-Point -2 -9)
+        (New-Point 6 -5)
+        (New-Point 0 14)
+        (New-Point 2 8)
+)
+
+$hull = Graham-Scan $testGift
+
+Write-Host "The points in the hull are: $($hull | % {"($($_.X), $($_.Y)) "})"
\ No newline at end of file
diff --git a/contents/graham_scan/graham_scan.md b/contents/graham_scan/graham_scan.md
index 586d209db..e0c84c723 100644
--- a/contents/graham_scan/graham_scan.md
+++ b/contents/graham_scan/graham_scan.md
@@ -32,6 +32,8 @@ We can find whether a rotation is counter-clockwise with trigonometric functions
 [import:18-20, lang="cpp"](code/c++/graham_scan.cpp)
 {% sample lang="coco" %}
 [import:4-8, lang="coconut"](code/coconut/graham_scan.coco)
+{% sample lang="ps1" %}
+[import:5-7, lang="coconut"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 If the output of this function is 0, the points are collinear.
@@ -66,6 +68,8 @@ In the end, the code should look something like this:
 [import:26-62, lang="cpp"](code/c++/graham_scan.cpp)
 {% sample lang="coco" %}
 [import:17-30, lang="coconut"](code/coconut/graham_scan.coco)
+{% sample lang="ps1" %}
+[import:9-25, lang="coconut"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 ### Bibliography
@@ -95,6 +99,8 @@ In the end, the code should look something like this:
 [import, lang="cpp"](code/c++/graham_scan.cpp)
 {%sample lang="coco" %}
 [import, lang="coconut"](code/coconut/graham_scan.coco)
+{% sample lang="ps1" %}
+[import, lang="coconut"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 <script>

From ed0c78e9a363f699babe219e0c69d9960569129e Mon Sep 17 00:00:00 2001
From: Patrick Kempf <34421580+PaddyKe@users.noreply.github.com>
Date: Sun, 4 Oct 2020 15:40:20 +0200
Subject: [PATCH 2/2] corrected language name in Markdown file

---
 contents/graham_scan/graham_scan.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/contents/graham_scan/graham_scan.md b/contents/graham_scan/graham_scan.md
index e0c84c723..d6b5e7a40 100644
--- a/contents/graham_scan/graham_scan.md
+++ b/contents/graham_scan/graham_scan.md
@@ -33,7 +33,7 @@ We can find whether a rotation is counter-clockwise with trigonometric functions
 {% sample lang="coco" %}
 [import:4-8, lang="coconut"](code/coconut/graham_scan.coco)
 {% sample lang="ps1" %}
-[import:5-7, lang="coconut"](code/powershell/GrahamScan.ps1)
+[import:5-7, lang="powershell"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 If the output of this function is 0, the points are collinear.
@@ -69,7 +69,7 @@ In the end, the code should look something like this:
 {% sample lang="coco" %}
 [import:17-30, lang="coconut"](code/coconut/graham_scan.coco)
 {% sample lang="ps1" %}
-[import:9-25, lang="coconut"](code/powershell/GrahamScan.ps1)
+[import:9-25, lang="powershell"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 ### Bibliography
@@ -100,7 +100,7 @@ In the end, the code should look something like this:
 {%sample lang="coco" %}
 [import, lang="coconut"](code/coconut/graham_scan.coco)
 {% sample lang="ps1" %}
-[import, lang="coconut"](code/powershell/GrahamScan.ps1)
+[import, lang="powershell"](code/powershell/GrahamScan.ps1)
 {% endmethod %}
 
 <script>