operator overloading 重载运算符

struct point {
    int x, y;
    point() {} // default constructor
    point (int _x, int _y) {
        x = _x; y = _y;
    }
};

struct point {
    int x, y;
    point() {} // default constructor
    point (int x, int y): x(x), y(y) {}
};

struct point {
    int x, y;
    // overloading of < operator
    bool operator<(const point &rhs) const{
        // your main logic for the comparator goes here
        return make_pair(x,y) < make_pair(rhs.x, rhs.y);
    }
};

struct node {
    int x,y;
    friend ostream & operator << (ostream &out,node &T);
};
ostream & operator << (ostream &out,node &T){
    out<<T.x<<" "<<T.y;
    return out;
}

struct node {
    int x,y;
    node operator ()(const node &T){return T;}
};

struct node {
    int x,y;
    node ():x(0),y(0){}
    node (int x,int y):x(x),y(y){}
    int len(){return x*x+y*y;}
    node operator - (const node &T){return node(x-T.x,y-T.y);}
    node operator + (const node &T){return node(x+T.x,y+T.y);}
    int operator * (const node &T){return x*T.x+y*T.y;}
    int operator / (const node &T){return x*T.y-y*T.x;}//叉积
};