用链表编写算法实现一元多项式相加及所写代码

可以参考以下代码实现：

class Node:
    def __init__(self, coefficient, exponent):
        self.coefficient = coefficient
        self.exponent = exponent
        self.next = None

class Polynomial:
    def __init__(self):
        self.head = None

    def add_node(self, coefficient, exponent):
        new_node = Node(coefficient, exponent)
        if not self.head:
            self.head = new_node
            return

        curr = self.head
        prev = None
        while curr and curr.exponent > exponent:
            prev = curr
            curr = curr.next

        if curr and curr.exponent == exponent:
            curr.coefficient += coefficient
            if curr.coefficient == 0:
                self.remove_node(curr, prev)
        else:
            new_node.next = curr
            if prev:
                prev.next = new_node
            else:
                self.head = new_node

    def remove_node(self, curr, prev):
        if prev:
            prev.next = curr.next
        else:
            self.head = curr.next

    def __str__(self):
        if not self.head:
            return "0"

        res = []
        curr = self.head
        while curr:
            if curr.coefficient != 0:
                res.append("{}x^{}".format(curr.coefficient, curr.exponent))
            curr = curr.next

        return " + ".join(res)

    def __add__(self, other):
        res = Polynomial()
        curr = self.head
        while curr:
            res.add_node(curr.coefficient, curr.exponent)
            curr = curr.next

        curr = other.head
        while curr:
            res.add_node(curr.coefficient, curr.exponent)
            curr = curr.next

        return res

实现了一个 `Node` 类和 `Polynomial` 类，其中 `Node` 存储了一项多项式的系数和指数，`Polynomial` 存储了多项式的链表，支持添加节点、移除节点、多项式的字符串表示和相加操作。