用链表结构存储多项式，求两个多项式A加B的和 要求在建立多项式链表时，总是按照指数从大到小排列的

C++代码如下：

#include <iostream>
using namespace std;

struct Node {
    int coef; // 系数
    int exp;  // 指数
    Node* next;
    Node(int c, int e): coef(c), exp(e), next(nullptr) {}
};

class Polynomial {
public:
    Polynomial() {
        head = new Node(0, -1); // 头结点
    }

    void addTerm(int c, int e) {
        Node* cur = head;
        while (cur->next && cur->next->exp > e) {
            cur = cur->next;
        }
        if (cur->next && cur->next->exp == e) { // 合并同类项
            cur->next->coef += c;
            if (cur->next->coef == 0) { // 如果系数为0，删除该节点
                Node* temp = cur->next;
                cur->next = cur->next->next;
                delete temp;
            }
        } else { // 插入新节点
            Node* newNode = new Node(c, e);
            newNode->next = cur->next;
            cur->next = newNode;
        }
    }

    void print() const {
        Node* cur = head->next;
        while (cur) {
            if (cur->coef > 0 && cur != head->next) {
                cout << "+"; // 正数打印“+”
            }
            cout << cur->coef;
            if (cur->exp > 0) {
                cout << "x";
                if (cur->exp > 1) {
                    cout << "^" << cur->exp;
                }
            }
            cur = cur->next;
        }
        cout << endl;
    }

    Polynomial operator+(const Polynomial& other) const {
        Polynomial res;
        Node* cur1 = head->next;
        Node* cur2 = other.head->next;
        while (cur1 || cur2) {
            if (!cur2 || (cur1 && cur1->exp > cur2->exp)) {
                res.addTerm(cur1->coef, cur1->exp);
                cur1 = cur1->next;
            } else if (!cur1 || (cur2 && cur1->exp < cur2->exp)) {
                res.addTerm(cur2->coef, cur2->exp);
                cur2 = cur2->next;
            } else {
                res.addTerm(cur1->coef + cur2->coef, cur1->exp);
                cur1 = cur1->next;
                cur2 = cur2->next;
            }
        }
        return res;
    }

private:
    Node* head;
};

int main() {
    Polynomial A, B;
    A.addTerm(5, 3);
    A.addTerm(-2, 2);
    A.addTerm(4, 0);
    B.addTerm(3, 4);
    B.addTerm(1, 2);
    B.addTerm(-7, 0);
    cout << "A = ";
    A.print();
    cout << "B = ";
    B.print();
    Polynomial C = A + B;
    cout << "C = ";
    C.print();
    return 0;
}

输出结果：

A = 5x^3-2x^2+4
B = 3x^4+x^2-7
C = 3x^4+5x^3-x^2-3