Redirect main domain to subdirectory

Following the following code sample I managed to redirect it, however the site URL on the browser show as domain.com/subdirectory and not domain.com.

RewriteEngine on RewriteCond %{HTTP_HOST} ^(www.)?example.com$   RewriteCond %{REQUEST_URI} !^/subdirectory/ RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$   /subdirectory/$  1 RewriteCond %{HTTP_HOST} ^(www.)?example.com$   RewriteRule ^(/)?$   subdirectory/index.html [L]