C++ list shuffle

// 来源：http://www.cplusplus.com/forum/general/207328/
template < typename T > void list_shuffle( std::list& lst ) // shuffle contents of a list
{
    // create a vector of (wrapped) references to elements in the list
    // http://en.cppreference.com/w/cpp/utility/functional/reference_wrapper
    std::vector< std::reference_wrapper< const T > > vec( lst.begin(), lst.end() ) ;

    // shuffle (the references in) the vector
    std::shuffle( vec.begin(), vec.end(), std::mt19937{ std::random_device{}() } ) ;

    // copy the shuffled sequence into a new list
    std::list shuffled_list {  vec.begin(), vec.end() } ;

    // swap the old list with the shuffled list
    lst.swap(shuffled_list) ;
}