设计一个一元稀疏多项式的简单计算器

设计一个一元稀疏多项式计算器，我们可以将其视为由一组系数和对应的变量指数构成的数据结构，例如`SparsePolynomial`。这种数据结构只存储非零项，可以提高空间效率。以下是一个简单的Python类实现：

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

class SparsePolynomial:
    def __init__(self):
        self.terms = []

    def add_term(self, coefficient, exponent):
        if coefficient != 0:
            term = Term(coefficient, exponent)
            self.terms.append(term)

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

    def degree(self):
        return max([term.exponent for term in self.terms if term.coefficient != 0])

# 示例用法
polynomial = SparsePolynomial()
polynomial.add_term(3, 2)  # 3x^2
polynomial.add_term(5, 1)  # 5x
polynomial.evaluate(2)  # 返回 34 (因为 3*2^2 + 5*2 = 34)

#