3.9_fraction_addtion_分数加法

class Fraction(object):

    def __init__(self, a, b):
        x = self.gcd(a, b)
        self.a = a // x
        self.b = b // x

    @staticmethod
    def gcd(a, b):
        """最大公约数"""

        while b > 0:
            r = a % b
            a, b = b, r
        return a

    @staticmethod
    def lcm(a, b):
        """最小公倍数"""

        return a * b // Fraction.gcd(a, b)

    def __str__(self):
        return f'{self.a} / {self.b}'

    def __add__(self, other):
        a = self.a
        b = self.b
        c = other.a
        d = other.b
        # 通分
        denominator = self.lcm(b, d)
        # 通分后，算出分子
        numerator = a * denominator // b + c * denominator // d
        return Fraction(numerator, denominator)

a = Fraction(1, 3)
b = Fraction(1, 2)

print(a + b)