幾何

code:cpp

struct Point {

int x, y;

explicit Point(const int x = 0, const int y = 0): x(x), y(y) {}

bool operator < (const Point& other) const {

return x < other.x or (x == other.x and y < other.y);

}

Point operator - (const Point& other) const {

return Point(x - other.x, y - other.y);

}

};

int cross(const Point& p, const Point& q) {

return p.x * q.y - p.y * q.x;

}