qswl不能用友元

rt 求助神犇 在写伪pair时

AC code:

struct Node
{
    int w, pos;
    bool operator < (const Node &x)const
    {
        return w > x.w;
    }
};

16pts code:

struct Node
{
    int w, pos;
    friend bool operator < (const Node &x, const Node &y) //友元是写在里面的... 
    {
        return y.w > x.w;
    }
};

???求助