pattern regex for apache rewrite rule

I have the following pattern on a few thousand lines I will like to use regex to convert to what I want

RewriteRule ^/omg/deadly-venom/?$ http://www.example.com/omg/deadly-venom [L,NC,R=301]
RewriteRule ^/buzz/get-on-it/?$ http://www.example.com/buzz/get-on-it/ [L,NC,R=301]

and others like this for a few thousand lines

So basically I want to have this

RewriteRule ^/omg/(deadly-venom)/?$ http://www.example.com/omg/$1 [L,NC,R=301]
RewriteRule ^/buzz/(get-on-it)/?$ http://www.example.com/buzz/$1 [L,NC,R=301]

How do I achieve this? I use the sublime text editor but can also use sed or awk in terminal.

UPDATED: the last / should not result in double slash before the $1 like this //$1 instead it should still be /$1 just look at the before and after from above and see lines with ending / and the one without