链表实现多项式的加法

poly.h

#ifndef POLYNOMIALCOMPUTE_POLY_H
#define POLYNOMIALCOMPUTE_POLY_H

struct PolyNode;
typedef struct PolyNode *Polynomial;

void Attach(int c, int e, Polynomial *pRear);
Polynomial PolyAdd(Polynomial P1, Polynomial P2);
void PrintPoly(Polynomial P);
void TestPoly();

#endif //POLYNOMIALCOMPUTE_POLY_H

poly.c

#include "poly.h"
#include <malloc.h>
#include <stdlib.h>
#include <stdio.h>

struct PolyNode {
    Polynomial link; // 指向下一个节点的位置
    int expon; // 指数，英文是 exponent
    int coef; // 系数，英文是 coefficient
};

// 新增一个节点
void Attach(int c, int e, Polynomial *pRear)
{
    Polynomial P;

    P = (Polynomial)malloc(sizeof(struct PolyNode)); // 分配空间
    P->coef = c; // 对新节点赋值
    P->expon = e;
    P->link = NULL;
    (*pRear)->link = P; // 尾节点指向P
    *pRear = P; // 修改 pRear 值
}

int Compare(int Lhs, int Rhs)
{
    return Lhs - Rhs;
}

Polynomial PolyAdd(Polynomial P1, Polynomial P2)
{
    Polynomial front, rear, temp;
    int sum;
    rear = (Polynomial)malloc(sizeof(struct PolyNode));
    front = rear; // 由 front 记录结果多项式链表头节点
    while (P1 && P2)
    { // 当两个多项式都有非零项待处理时
        switch (Compare(P1->expon, P2->expon))
        {
            case 1:
                Attach(P1->coef, P1->expon, &rear);
                P1 = P1->link;
                break;
            case -1:
                Attach(P2->coef, P2->expon, &rear);
                P2 = P2->link;
                break;
            case 0:
                sum = P1->coef + P2->coef;
                if (sum) Attach(sum, P1->expon, &rear);
                P1 = P1->link;
                P2 = P2->link;
                break;
        }
    }
    // 将未处理完的另一个多项式的所有节点依次复制到结果多项式中去
    for(; P1; P1 = P1->link) Attach(P1->coef, P1->expon, &rear);
    for(; P2; P2 = P2->link) Attach(P2->coef, P2->expon, &rear);
    rear->link = NULL;
    temp = front;
    front = front->link; // 令 front 指向结果多项式的第一个非零项
    free(temp); // 释放临时空表头节点
    return front;
}

void PrintPoly(Polynomial P)
{
    Polynomial tmp = P;
    for(; tmp; tmp = tmp->link)
    {
        printf("%d %d   ", tmp->coef, tmp->expon);
    }
}

void TestPoly()
{
    int P1Coef[5] = {3, 4, -1, 2, -1};
    int P1expon[5] = {5, 4, 3, 1, 0};
    int P2Coef[4] = {2, 1, -7, 1};;
    int P2expon[4] = {4, 3, 2, 1};

    Polynomial P1, P2;
    P1 = (Polynomial)malloc(sizeof(struct PolyNode));
    P2 = (Polynomial)malloc(sizeof(struct PolyNode));
    
    Polynomial P1Rear;
    P1Rear = P1;

    Polynomial P2Rear;
    P2Rear = P2;

    for (int i = 0; i < 5; ++i)
    {
        Attach(P1Coef[i], P1expon[i], &P1Rear); // 注意这里传的是地址！！！
    }
    P1 = P1->link; // 因为第一个节点没有存储数据，所以 P1 要往后挪一位

    for (int i = 0; i < 4; ++i)
    {
        Attach(P2Coef[i], P2expon[i], &P2Rear);
    }
    P2 = P2->link;

    Polynomial res = PolyAdd(P1, P2);

    PrintPoly(P1);
    printf("\n");
    PrintPoly(P2);
    printf("\n");
    PrintPoly(res);

}

main.c(测试函数)

#include "poly.h"

// 测试函数
int main()
{
    TestPoly();

    return 0;
}

测试：

测试样例：

测试结果：