Routing to specific controller in case controller/method is not found.

Try something like this:

PHP Code:

$route['controller-1/method-1/(:any)'] = 'controller-1/method-1/$1';
$route['controller-2/(:any)'] = 'controller-2/method-2/$1';
$route['(:any)'] = 'controller-3/method-3/$1'; 


You can also use:

PHP Code:

$route['something-1/controller-1/method-1/(:any)'] = 'controller-1/method-1/$1';
$route['something-2/controller-2/(:any)'] = 'controller-2/method-2/$1';
$route['something-3/(:any)'] = 'controller-3/method-3/$1'; 


If you did not, read the URI Routing in the documentation, where you can find more tips.