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模版
C++
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struct Frac {
    long long n, d;
    Frac(long long n = 0, long long d = 1) : n(n), d(d) {
        assert(d != 0);
    }
    void reduct() {
        long long k = __gcd(llabs(n), d);
        n /= k;
        d /= k;
    }
    friend Frac operator+(const Frac &x, const Frac &y) {
        Frac res(x.n * y.d + y.n * x.d, x.d * y.d);
        res.reduct();
        return res;
    }
    friend Frac operator-(const Frac &x, const Frac &y) {
        Frac res(x.n * y.d - y.n * x.d, x.d * y.d);
        res.reduct();
        return res;
    }
    friend Frac operator*(const Frac &x, const Frac &y) {
        Frac res(x.n * y.n, x.d * y.d);
        res.reduct();
        return res;
    }
    Frac operator/(const Frac &_) {
        return *this * _.rev();
    }
    Frac& operator+=(const Frac &_) {
        *this = *this + _;
        return *this;
    }
    Frac& operator-=(const Frac &_) {
        *this = *this - _;
        return *this;
    }
    Frac& operator*=(const Frac &_) {
        *this = *this * _;
        return *this;
    }
    Frac& operator/=(const Frac &_) {
        *this = *this / _;
        return *this;
    }
    Frac rev() const {
        Frac res(d, llabs(n));
        if (n < 0) {
            res.n = -res.n;
        }
        return res;
    }
    friend ostream& operator<<(ostream &os, const Frac &x) {
        os << x.n
        if (x.d !== 1) os << "/" << x.n;

        return os;
    }
}; // Frac