Re: All Permutations of 10 Things Taken 7 at a Time?

On Jan 10, 11:55 pm, sherman wrote:


Consider an algorithm like this for the first part:

template <class T>
void nChooseK(std::vector<T> const & items, int const k, std::vector<
std::vector<T> > & results)
{
    assert( k >= 0 );

    if(k == 0) // if we are choosing zero items
    { // there is only one way to choose zero items, and that is an
empty set
        results.push_back( std::vector<T>() );
    }
    else if(k <= items.size())
    {
        for(std::vector<T>::const_iterator iter = items.begin();
iter != items.end(); ++iter)
        {
            std::vector<T> stripped_items(iter+1, items.end());
            std::vector< std::vector<T> > stripped_results;
            nChooseK(stripped_items, k-1, stripped_results);
            for(std::vector< std::vector<T> >::iterator inner_iter =
stripped_results.begin(); inner_iter != stripped_results.end(); +
+inner_iter)
            {
                inner_iter->push_back(*iter);
                results.push_back(*inner_iter);
            }
        }
    }
    // else we are being asked to select more than the number of items
we
    // have, and there is no way to do that so don't add anything to
the
    // result
}

And std::next_permutation for the next part.