Codeigniter路由正则表达式

I have this:

$route['^[a-zA-Z]{2}$'] = "state";

$route['^[a-zA-Z]{2}$/(:any)'] = "state/city";

And these controllers

state.php

class State extends CI_Controller {

    public function index () 
    {
        echo "OK"; 
    } 
    public function city () 
    {
       echo "Not OK"; 
    } 
}

The first route works perfectly, while the second does not. She should call the city of the State class method but does not call!

url:

http://foo.bar/SP/ ---> OK
http://foo.bar/SP/SANTOS -> 404!

Remove the $ that anchors to the end of the string:

$route['^[a-zA-Z]{2}/(:any)'] = "state/city";