2016 Update

Task/Best-shuffle/PowerShell/best-shuffle-1.psh

@@ -0,0 +1,52 @@
+#  Calculate best possible shuffle score for a given string
+#  (Split out into separate function so we can use it separately in our output)
+function Get-BestScore ( [string]$String )
+    {
+    #  Convert to array of characters, group identical characters,
+    #  sort by frequecy, get size of first group
+    $MostRepeats = $String.ToCharArray() |
+                    Group |
+                    Sort Count -Descending |
+                    Select -First 1 -ExpandProperty Count
+
+    #  Return count of most repeated character minus all other characters (math simplified)
+    return [math]::Max( 0, 2 * $MostRepeats - $String.Length )
+    }
+
+function Get-BestShuffle ( [string]$String )
+    {
+    #  Convert to arrays of characters, one for comparison, one for manipulation
+    $S1 = $String.ToCharArray()
+    $S2 = $String.ToCharArray()
+
+    #  Calculate best possible score as our goal
+    $BestScore = Get-BestScore $String
+
+    #  Unshuffled string has score equal to number of characters
+    $Length = $String.Length
+    $Score = $Length
+
+    #  While still striving for perfection...
+    While ( $Score -gt $BestScore )
+        {
+        #  For each character
+        ForEach ( $i in 0..($Length-1) )
+            {
+            #  If the shuffled character still matches the original character...
+            If ( $S1[$i] -eq $S2[$i] )
+                {
+                #  Swap it with a random character
+                #  (Random character $j may be the same as or may even be
+                #   character $i. The minor impact on speed was traded for
+                #   a simple solution to guarantee randomness.)
+                $j = Get-Random -Maximum $Length
+                $S2[$i], $S2[$j] = $S2[$j], $S2[$i]
+                }
+            }
+        #  Count the number of indexes where the two arrays match
+        $Score = ( 0..($Length-1) ).Where({ $S1[$_] -eq $S2[$_] }).Count
+        }
+    #  Put it back into a string
+    $Shuffle = ( [string[]]$S2 -join '' )
+    return $Shuffle
+    }

Task/Best-shuffle/PowerShell/best-shuffle-2.psh

@@ -0,0 +1,6 @@
+ForEach ( $String in ( 'abracadabra', 'seesaw', 'elk', 'grrrrrr', 'up', 'a' ) )
+    {
+    $Shuffle = Get-BestShuffle $String
+    $Score   = Get-BestScore   $String
+    "$String, $Shuffle, ($Score)"
+    }

Task/Best-shuffle/PowerShell/best-shuffle.psh

@@ -1,10 +0,0 @@
-function Best-Shuffle($strings){
-	foreach($string in $strings){
-		$sa1 = $string.ToCharArray()
-		$sa2 = Get-Random -InputObject $sa1 -Count ([int]::MaxValue)
-		$string = [String]::Join("",$sa2)
-		echo $string
-	}
-}
-
-Best-Shuffle "abracadabra", "seesaw", "pop", "grrrrrr", "up", "a"