You can either fully-qualify the class name
Route::get('/posts/{post}', \App\Http\Livewire\Post\Show::class);
Route::get('/categories/{categories}', \App\Http\Livewire\Category\Show::class);
or, alias a different name
use App\Http\Livewire\Post\Show as PostShow;
use App\Http\Livewire\Category\Show as CategoryShow;
// ...
Route::get('/posts/{post}', PostShow::class);
Route::get('/categories/{categories}', CategoryShow::class);