cme193 demo: Rational class

rational.py

class Rational:
    def __init__(self, p, q=1):
        g = gcd(p, q)
        self.p = p / g
        self.q = q / g
        
    def __add__(self, other):
        p = self.p * other.q + other.p * self.q
        q = self.q * other.q
        return Rational(p, q)
    
    def __sub__(self, other):
        p = self.p * other.q - other.p * self.q
        q = self.q * other.q
        return Rational(p, q)
    
    def __mul__(self, other):
        p = self.p * other.p
        q = self.q * other.q
        return Rational(p, q)
    
    def __div__(self, other):
        p = self.p * other.q
        q = self.q * other.p
        return Rational(p, q)
        
    def __repr__(self):
        if self.q == 1:
            return '{}'.format(self.p)
        return '{}/{}'.format(self.p, self.q)

def gcd(a, b):
    if b == 0:
        return a
    else:
        return gcd(b, a%b)