分数类.cpp

struct frac{
    using ll = long long;
    ll fz, fm;
    frac() = default;

    frac(ll fz, ll fm) { // 构造函数变量名最好不要跟类成员名一样！
        assert(fm != 0);
        if (fm < 0) fm *= -1, fz *= -1;
        ll g = __gcd(abs(fz), fm);
        fz /= g, fm /= g;
        this->fz = fz, this->fm = fm;
    }

    frac(ll x):fz(x),fm(1){} // implicit conversion

    frac operator*(const frac &other)const{
        return {fz * other.fz, fm * other.fm};
    }

    frac operator-()const{
        return {-fz, fm};
    }
    frac operator-(const frac &other)const{
        return *this + (-other);
    }
    frac operator+(const frac &other)const{
        ll _fz = fz * other.fm + fm * other.fz;
        ll _fm = fm * other.fm;
        return {_fz, _fm};
    }
    bool operator==(const frac &other)const{
        return other.fz == fz && other.fm == fm;
    }
    bool operator<(const frac &other)const{
        return fz * other.fm < other.fz * fm;
    }
    bool operator>(const frac &other)const{
        return fz * other.fm > other.fz * fm;
    }
    bool operator>=(const frac &other)const{
        return !(*this < other);
    }
    bool operator<=(const frac &other)const{
        return !(*this > other);
    }
    frac operator/(const int &x)const{
        return {fz, fm * x};
    }
    double to_double() const {
        return fz / (double)fm;
    }

};