STL中的rotate算法！！牛逼

rotate.cpp

    template <class ForwardIterator>
    void rotateSTL(ForwardIterator first, ForwardIterator middle, 
                   ForwardIterator last)
    {
        using std::swap;
        ForwardIterator next = middle;
        while(first != next)
        {
            swap(*first++, *next++);
            if(next == last){ next = middle;}
            else if(first == middle){ middle = next; }
        }
    }