求解单项式和多项式Python类

class Monomial:
    def __init__(self, coefficient, exponent):
        self.coefficient = coefficient
        self.exponent = exponent

    def __str__(self):
        if self.exponent == 0:
            return str(self.coefficient)
        elif self.exponent == 1:
            return f"{self.coefficient}x"
        else:
            return f"{self.coefficient}x^{self.exponent}"

    def evaluate(self, x):
        return self.coefficient * (x ** self.exponent)

    def derivative(self):
        if self.exponent == 0:
            return Monomial(0, 0)
        else:
            return Monomial(self.coefficient * self.exponent, self.exponent - 1)

class Polynomial:
    def __init__(self, terms):
        self.terms = terms

    def __str__(self):
        result = ""
        for i, term in enumerate(self.terms):
            if i > 0 and term.coefficient >= 0:
                result += "+ "
            result += str(term)
            result += " "
        return result

    def evaluate(self, x):
        result = 0
        for term in self.terms:
            result += term.evaluate(x)
        return result

    def derivative(self):
        derivative_terms = []
        for term in self.terms:
            derivative_terms.append(term.derivative())
        return Polynomial(derivative_terms)

# 创建单项式
m1 = Monomial(3, 2)
m2 = Monomial(-2.5, 3)

# 创建多项式
p = Polynomial([m1, m2, Monomial(4, 0)])

# 打印多项式
print(p)  # 输出：3x^2 - 2.5x^3 + 4

# 求多项式在x=2处的值
print(p.evaluate(2))  # 输出：-19.5

# 求多项式的导数
derivative_p = p.derivative()
print(derivative_p)  # 输出：6x - 7.5x^2