【模板】极角排序.cpp

using Point = pair<int,int>;
ll cross(const Point& a, const Point& b) {
    return 1ll * a.first * b.second - 1ll * a.second * b.first;
}
// 逆时针
// 参考 mnbvmar 的写法：https://codeforces.com/contest/1284/submission/68178688
bool cmp_polar(const Point& a, const Point& b) {
    bool aorig = a.second > 0;
    bool borig = b.second > 0;
    if (aorig != borig) {
        return aorig > borig;
    }
    return cross(a, b) > 0;
}