两个一元多项式相加

#include <stdio.h>
#include <stdlib.h>

struct PolyNode {
    int coefficient;        //系数
    int  exponent;            //指数
    struct PolyNode* next;
};

typedef struct PolyNode *Polynomial;
Polynomial p1, p2;

//初始化一元多项式链表
void InitPolynomial(Polynomial *p);
// 将比较之后的项插入到新链的尾部
void Attach(int c, int e, Polynomial* pRear);
//比较两项指数的大小
int Compare(int exponent1, int exponent2);
//比较两个多项式的各项，依次插入到新项
Polynomial PolyAdd(Polynomial P1, Polynomial P2);
//打印链表的值
void printPolynomial(Polynomial P);

int main()
{
    InitPolynomial(&p1);
    InitPolynomial(&p2);
    Polynomial p3 = PolyAdd(p1, p2);
    printPolynomial(p1);
    printPolynomial(p2);
    printPolynomial(p3);

    return 0;
}


//初始化一元多项式链表
void InitPolynomial(Polynomial *p)        //二级指针
{
    
    (*p) = (Polynomial)malloc(sizeof(struct PolyNode));
    Polynomial head = *p;
    int coef, expon;
    scanf_s("%d %d", &coef, &expon);
    while (coef!=0 && expon != 0)
    {
        struct PolyNode* node = (struct PolyNode*)malloc(sizeof(struct PolyNode));
        node -> coefficient = coef;
        node -> exponent = expon;
        node->next = NULL;
        (*p) ->next = node;
        (*p) = node;
        scanf_s("%d %d", &coef, &expon);
    }
    (*p) = head;
    (*p) = (*p) -> next;
}

//将比较之后的项插入到新链的尾部
void Attach(int c, int e, Polynomial *pRear)
{
    Polynomial P = (Polynomial)malloc(sizeof(struct PolyNode));
    P -> coefficient = c;
    P ->exponent = e;
    (*pRear)->next = P;
    P->next = NULL;
    (*pRear) = P;        //因为这里改变了形参pRear的指向，所以参数列表必须传二级指针
}

int Compare(int exponent1, int exponent2)
{
    if (exponent1 == exponent2)
        return 0;
    else
    if (exponent1 > exponent2)
        return 1;
    return -1;
}

//比较两个多项式的各项，依次插入到新项
Polynomial PolyAdd(Polynomial P1, Polynomial P2)
{
    Polynomial front, rear, temp;
    int sum;
    rear = front = (Polynomial)malloc(sizeof(struct PolyNode));
    while (P1 && P2)
    {
        switch (Compare(P1->exponent, P2->exponent))
        {
        case 1:
            Attach(P1->coefficient, P1->exponent, &rear);
            P1 = P1->next;
            break;

        case -1:
            Attach(P2->coefficient, P2->exponent, &rear);
            P2 = P2->next;
            break;

        case 0:
            sum = P1->coefficient + P2->coefficient;
            if (sum)
            Attach(sum, P1->exponent, &rear);
            P1 = P1->next;
            P2 = P2->next;
            break;
        }
    }
    for (; P1; P1 = P1->next)
        Attach(P1->coefficient, P1->exponent, &rear);
    for (; P2; P2 = P2->next)
        Attach(P2->coefficient, P2->exponent, &rear);

    temp = front;
    front = front->next;
    free(temp);
    return front;
}

void printPolynomial(Polynomial P)
{
    Polynomial node = P;
    if (P)
    {
        for (; node ; node = node->next)
            printf("%dX^%d ", node->coefficient, node->exponent);
        printf("
");
    }
    return;
}

 初始化的函数也可是这样：

//初始化一元多项式链表
void InitPolynomial(Polynomial *p)        //二级指针
{

    (*p) = (Polynomial)malloc(sizeof(struct PolyNode));
    Polynomial rear = *p;
    int coef, expon;
    int cnt;
    scanf_s("%d", &cnt);
    while (cnt--)　　　　　　//多项式的项数
    {    
        scanf_s("%d %d", &coef, &expon);
        Attach(coef, expon, &rear);
    }
    Polynomial temp = (*p);
    (*p) = (*p) -> next; 
    free(temp);
}