Fractions

class Fraction
{
    var n : Int = 0;
    var d : Int = 1;
    
    init()
    {
        
    }
    
    init( numerator n : Int, denominator d : Int )
    {
        if ( d != 0 )
        {
            self.n = n;
            self.d = d;
        }
    }
    
    func add( other : Fraction ) -> Fraction
    {
        var f = Fraction( numerator : self.n * other.d + self.d * other.n, denominator : self.d * other.d );
        f.simplify();
        return f;
        
    }
    
    func subtract(other: Fraction) -> Fraction
    {
        var f = Fraction( numerator : (self.n * other.d) - (self.d * other.n), denominator : self.d * other.d);
        f.simplify();
        return f;
    }
    
    func multiply(other: Fraction) -> Fraction
    {
        var f = Fraction( numerator : self.n * other.n, denominator : self.d * other.d );
        f.simplify();
        return f;
    }
    
    func divide(other: Fraction) -> Fraction
    {
        var f = Fraction( numerator : self.n * other.d, denominator : self.d * other.n );
        f.simplify();
        return f;
    }
    
    func simplify()
    {
        
        let signN = self.n >= 0 ? 1 : -1
        let signD = self.d >= 0 ? 1 : -1
        let sign = signN * signD
        
        var u = self.n * sign
        var v = self.d
        var temp: Int;
        while ( v != 0 )
        {
            temp = u % v
            u = v
            v = temp
        }
        self.n /= u
        self.d /= u
    }
}