【一元多项式算法】设一个一元多项式采用带头结点的单链表存储，所有结点 按照升幂方式链接。设计一个算法，求两个多项式 A 和 B 的乘积，结果多项式 C 存放在新辟的空间中。

【一元多项式算法】设一个一元多项式采用带头结点的单链表存储，所有结点
按照升幂方式链接。设计一个算法，求两个多项式 A 和 B 的乘积，结果多项式 C
存放在新辟的空间中。

#include
#include

typedef struct node {
     
	int coef;
	int expn;
	struct node* next;
}node;


struct node* create(int n) {
     
	int i, num, g;
	struct node* ptr = NULL, * head = NULL, * tail = NULL;
	printf("Input %d data:\n", n);
	for (i = 0; i < n; i++)
	{
     
		scanf_s("%d %d", &num, &g);
		ptr = (struct node*)malloc(sizeof(struct node));
		ptr->coef = num;
		ptr->expn = g;
		ptr->next = NULL;
		if (head == NULL) head = ptr;
		else tail->next = ptr;
		tail = ptr;
	}
	return head;
}


struct node* Multiply(node* L1, node* L2) {
     
	int temp;
	node* ptr=NULL, * head=NULL, * tail=NULL, * ptr1=NULL, * ptr2=NULL;
	for (ptr1 = L1; ptr1 != NULL; ptr1 = ptr1->next) {
     
		for (ptr2 = L2; ptr2 != NULL; ptr2 = ptr2->next) {
     
			ptr = (node*)malloc(sizeof(node));
			ptr->coef = (ptr1->coef) * (ptr2->coef);
			ptr->expn = ptr1->expn + ptr2->expn;
			ptr->next = NULL;
			if (head == NULL)head = ptr;
			else tail->next = ptr;
			tail = ptr;
		}
	}
	for (ptr1 = head; ptr1 != NULL; ptr1 = ptr1->next) {
     
		for (ptr2 = ptr1->next, tail = ptr1; ptr2 != NULL;) {
     
			if (ptr1->expn == ptr2->expn) {
     
				ptr1->coef = ptr1->coef + ptr2->coef;
				tail->next = ptr2->next;
				free(ptr2);
				ptr2 = tail->next;
			}
			else {
     
				tail = ptr2;
				ptr2 = ptr2->next;
			}
		}
	}

	for (ptr1 = head; ptr1->next != NULL; ptr1 = ptr1->next) {
     
		for (ptr2 = ptr1->next; ptr2 != NULL; ptr2 = ptr2->next) {
     
			if (ptr1->expn < ptr2->expn) {
     
				temp = ptr1->expn;
				ptr1->expn = ptr2->expn;
				ptr2->expn = temp;
				temp = ptr1->coef;
				ptr1->coef = ptr2->coef;
				ptr2->coef = temp;
			}
		}
	}
	for (ptr = head; ptr != NULL;) {
     
		if (ptr->coef==0) {
     
			if (ptr == head) {
     
				head = head->next;
				free(ptr);
				ptr = head;
			}
			else {
     
				ptr1->next = ptr->next;
				free(ptr);
				ptr = ptr1->next;
			}
		}
		else {
     
			ptr1 = ptr;
			ptr = ptr->next;
		}
	}
	return head;
}


void print(node* L) {
     
	node* p;
	p = L;
	while (p!=NULL) {
     
		printf("%d %d\n", p->coef, p->expn);
		p= p->next;
	}
}


int main() {
     
	int n1, n2;
	node* L1, * L2, * L;
	printf("Input n1:");
	scanf_s("%d", &n1);
	L1 = create(n1);
	printf("Input n2:");
	scanf_s("%d", &n2);
	L2 = create(n2);
	L = Multiply(L1, L2);
	printf("结果为：\n");
	print(L);
}