#include <string>
#include <iostream>
#include <vector>
#include <numeric>
#include <sstream>

using namespace std;

struct Book
{
    string name{};
    double weight{};
};

class Bookshelf
{
private:
    vector<Book> shelf;
    double max_weight;

    double current_weight() const
    {
        return std::accumulate(begin(shelf), end(shelf), 0.0, 
                               [] (double lhs, Book const& rhs) {
                                   return lhs + rhs.weight;
                               });
    }

public:
    Bookshelf(double max_weight)
	: shelf{}, max_weight{max_weight}
    {}

    void put_book(Book const& book)
    {
	if ( current_weight() + book.weight <= max_weight )
	{
	    shelf.push_back(book);
	}
    }

    string to_string() const
    {
        stringstream strs{""};
        for ( auto const& book : shelf )
        {
            strs << book.name << " ";
        }
        return strs.str();

    }
};

int main()
{
    Bookshelf bookshelf{5.0};
    bookshelf.put_book( Book{"The Hobbit", 0.4}      );
    bookshelf.put_book( Book{"Learning Python", 3.6} );
    bookshelf.put_book( Book{"C++ Primer", 2.0}      );
    bookshelf.put_book( Book{"Learning C++", 2.2}    );
    bookshelf.put_book( Book{"C++ Templates", 2.0}   );
    bookshelf.put_book( Book{"The Pickaxe", 0.9}     );
 
    cout << bookshelf.to_string() << endl;
    return 0;
}