How to create the following condition in nginx?

Question

Nginx

If the user requests the site address "/" and the sid cookie exists, then redirect to "/account/"
If the user requests any other page and the sid cookie does NOT exist, then redirect to "/"
Here is my code:

map "$cookie_sid:$request_filename" $path {
  default                 $request_filename;
  ":~^/.+"                "/";
  "~.+:/"                 "/account/";
}

location / is worth rewrite ^ $path;