2016 Update

Task/Inverted-index/PowerShell/inverted-index-1.psh

@@ -0,0 +1,43 @@
+function Index-File ( [string[]]$FileList )
+    {
+    #  Create index hashtable, as needed
+    If ( -not $Script:WordIndex ) { $Script:WordIndex = @{} }
+
+    #  For each file to be indexed...
+    ForEach ( $File in $FileList )
+        {
+        #  Find any previously existing entries for this file
+        $ExistingEntries = $Script:WordIndex.Keys | Where { $Script:WordIndex[$_] -contains $File }
+
+        #  For any previously existing entries
+        #    Delete them (prior to reindexing the file)
+        ForEach ( $Key in $ExistingEntries )
+            {
+            $Script:WordIndex[$Key] = @( $Script:WordIndex[$Key] | Where { $_ -ne $File } )
+            }
+
+        #  Get the contents of the file, split on non-alphanumeric characters, and remove duplicates
+        $Words = ( Get-Content $File ) -split '[^a-zA-Z\d]' | Sort -Unique
+
+        #  For each word in the file...
+        ForEach ( $Word in $Words )
+            {
+            #  If the entry for the word already exists...
+            If ( $Script:WordIndex[$Word] )
+                {
+                #  Add the file name to the entry
+                $Script:WordIndex[$Word] += $File
+                }
+            Else
+                {
+                #  Create a new entry
+                $Script:WordIndex[$Word] = @( $File )
+                }
+            }
+        }
+    }
+
+function Find-Word ( [string]$Word )
+    {
+    return $WordIndex[$Word]
+    }