采用链式存储结构，将两个线性链表表示的一元多项式相加减，求导并输出。

#include<stdio.h>

 #include<stdlib.h>
 typedef struct lnode
 {
  int coef;  //系数 
  int index; //指数
struct lnode *next; 
 }node;
 node *Create()      //头插法建立一元多项式
 {
  node *p1,*p2,*head;
  int x,y,i = 1;
  head = (node *)malloc(sizeof(node));
  head->next = NULL;
  p1 = head;
  p2 = head;
  for(i=1; ; i++)
  {
  p2 = (node *)malloc(sizeof(node));
  printf("输入第%d项的系数，指数:",i);
  scanf("%d%d",&x,&y);
  if(x==0 && y==0)            //输入0 0时表示输入完成 
  {
  break; 
}
if(x == 0)
{
continue;
}
  p2->coef = x;
  p2->index = y;
  p2->next = p1->next;
  p1->next = p2;


}
return head;
 }
 void Sort (node *head)             //将多项式中相同指数的项合并 
 {
  node *p,*q,*p1;
  for(p = head->next;p->next!=NULL;p = p->next)
  {
  for(q = p;q->next!=NULL;q=q->next)
  {
  if(p->index == q->next->index)
  {
  p->coef = p->coef + q->next->coef;    //相同指数的项合并 
  q->next->coef = 0;
  q->next->index = 0;
}
}
}
p = head;
q = p;
while(q->next!=NULL)
{
p1 = q;
q = q->next;
if(q->coef==0 && q->index==0)
{
p1->next = q->next;
free(q);
q = p1;
}
}
 }
 int Print(node *head)          //打印函数 
 {
  node *p;
  int x,y;
  if(head->next == NULL)
  return 0;
else
  p = head->next;
  while(p->next != NULL)
  {
if(p->index == 0)
{
printf("%d+",p->coef);
}
else if(p->next->coef<0)
{
printf("%dx^%d",p->coef,p->index);
}
else
{
  printf("%dx^%d+",p->coef,p->index);
  }
p = p->next;
}
if(p->index == 0)
{
printf("%d\n",p->coef);
}
else
{
  printf("%dx^%d\n",p->coef,p->index);
  }
return 1;
 }
 void Plus(node *head1,node *head2)          //多项式相加 
 {
  node *p,*q,*p1;
  p = head1;
  q = head2;
  for(p = head1->next;p!=NULL;p = p->next)
  {
  for(q = head2->next;q!=NULL;q = q->next)
  {
  if(p->index == q->index)       // //相同指数的项合并 
  {
  p->coef = p->coef + q->coef;
  q->coef = 0;
  q->index = 0;
}
}
}
for(q = head2->next;q!=NULL;q = q->next)
{
if(q->coef!=0 && q->index!=0)         //将第二个多项式中与第一个多项式指数不同的项 添加入第一个多项式 
{
p1 = (node *)malloc(sizeof(node));
p1->coef = q->coef;
p1->index = q->index;
p1->next = head1->next;
head1->next = p1;
}
}
Print(head1);
 }
 void Minus(node *head1,node *head2)         // 多项式相加（同相减） 
 {
  node *p,*q,*p1;
  p = head1;
  q = head2;
  for(p = head1->next;p!=NULL;p = p->next)
  {
  for(q = head2->next;q!=NULL;q = q->next)
  {
  if(p->index == q->index)
  {
  p->coef = p->coef - q->coef;
  q->coef = 0;
  q->index = 0;
}
}
}
for(q = head2->next;q!=NULL;q = q->next)
{
if(q->coef!=0 && q->index!=0)
{
p1 = (node *)malloc(sizeof(node));
p1->coef = 0-q->coef;
p1->index = q->index;
p1->next = head1->next;
head1->next = p1;
}
}
Print(head1);
 }
 void derivative(node *head)    //求多项式的导数 
 {
  node *p;
  p = head->next;
  while(p!=NULL)
  {
  p->coef = p->coef*p->index;
  p->index = p->index-1;
  p = p->next;
}
printf("多项式的导数为:");
Print(head);
 }
 int main()
 {
  node *head1,*head2,*head;
  int x;
  printf("输入第一个多项式的系数，指数（输入0 0时结束输入）:\n");
  head1 = Create();
  Sort(head1);
Print(head1);
printf("输入第二个多项式的系数，指数（输入0 0时结束输入）:\n");
  head2 = Create();
  Sort(head2);
Print(head2);
printf("选择运算:");
scanf("%d",&x);
switch(x)
{
case 1:derivative(head1);break;
case 2:derivative(head2);break;
case 3:Plus(head1,head2);break;
case 4: Minus(head1,head2);break;
}
 }