编写一个程序用单链表存储多项式，并实现两个一元多项式A与B相加的函数。A，B刚开始是无序的，A与B之和按降序排列。

好的，这里给出一份Python代码实现，具体注释见代码：

class Node:
    def __init__(self, coef, exp):
        self.coef = coef  # 系数
        self.exp = exp  # 指数
        self.next = None  # 指向下一个节点的指针


class PolyList:
    def __init__(self):
        self.head = None  # 头节点

    # 向链表中插入一项
    def insert(self, coef, exp):
        if coef != 0:  # 系数为0时不插入
            node = Node(coef, exp)
            if self.head is None:  # 如果链表为空，则新节点即为头节点
                self.head = node
            else:
                cur = self.head
                while cur.next is not None and cur.next.exp > exp:
                    cur = cur.next
                if cur.exp == exp:  # 指数相同，则系数相加
                    cur.coef += coef
                    if cur.coef == 0:  # 如果系数为0，则删除该节点
                        self.delete(cur.exp)
                else:
                    node.next = cur.next
                    cur.next = node

    # 从链表中删除某一项
    def delete(self, exp):
        if self.head is None:
            return
        if self.head.exp == exp:  # 如果头节点即为要删除的节点
            self.head = self.head.next
        else:
            cur = self.head
            while cur.next is not None and cur.next.exp != exp:
                cur = cur.next
            if cur.next is not None:
                cur.next = cur.next.next

    # 对链表按降序排列
    def sort(self):
        if self.head is None or self.head.next is None:
            return
        tail = None
        while tail != self.head.next:
            cur = self.head
            while cur.next != tail:
                if cur.next.exp < cur.exp:
                    cur.coef, cur.exp, cur.next.coef, cur.next.exp = cur.next.coef, cur.next.exp, cur.coef, cur.exp
                cur = cur.next
            tail = cur

    # 输出多项式
    def output(self):
        cur = self.head
        while cur is not None:
            print("{:.1f} {}".format(cur.coef, cur.exp), end=" ")
            cur = cur.next
        print()

    # 多项式相加
    def add(self, poly):
        res = PolyList()
        p1, p2 = self.head, poly.head
        while p1 is not None and p2 is not None:
            if p1.exp > p2.exp:
                res.insert(p1.coef, p1.exp)
                p1 = p1.next
            elif p1.exp < p2.exp:
                res.insert(p2.coef, p2.exp)
                p2 = p2.next
            else:
                res.insert(p1.coef + p2.coef, p1.exp)
                p1, p2 = p1.next, p2.next
        while p1 is not None:
            res.insert(p1.coef, p1.exp)
            p1 = p1.next
        while p2 is not None:
            res.insert(p2.coef, p2.exp)
            p2 = p2.next
        res.sort()
        return res


# 输入多项式A
poly_a = PolyList()
lst = input().split()
for i in range(0, len(lst), 2):
    coef, exp = float(lst[i]), int(lst[i + 1])
    poly_a.insert(coef, exp)

# 输入多项式B
poly_b = PolyList()
lst = input().split()
for i in range(0, len(lst), 2):
    coef, exp = float(lst[i]), int(lst[i + 1])
    poly_b.insert(coef, exp)

# 多项式相加
poly_sum = poly_a.add(poly_b)

# 输出结果
poly_sum.output()

输入样例：

1.2 0 2.5 1 3.2 3 -2.5 5
-1.2 0 2.5 1 3.2 3 2.5 5 5.4 10

输出样例：

5.4 10 6.4 3 5.0 1