数据结构之链表创建一元多项式，求一元多项式之和

#include "stdafx.h"
#include "stdio.h"
#include "malloc.h"
#include "stdlib.h"
#define LEN sizeof(node);
typedef struct polynode
{
  int coef;//系数
  int exp;//指数
  struct polynode *next;
}node,*ListPolynode;
/*倒序创建一元多项式*/
void createPoly(ListPolynode L,int n)
{
  ListPolynode p;
  for (int i=n;i>0;i--)
  {
    p=(ListPolynode)malloc(sizeof(node));
    printf("请输入第%d项系数\n",i);
    scanf_s("%d",&p->coef);
    printf("请输入第%d项指数\n",i);
    scanf_s("%d",&p->exp);
    p->next=L->next;
    L->next=p;
  }
}
/*正序创建一元多项式*/
ListPolynode createPoly1(ListPolynode L,int n)
{
  ListPolynode p;
  ListPolynode head=L;
  for (int i=0;i<n;i++)
  {
    p=(ListPolynode)malloc(sizeof(node));
    printf("请输入第%d项系数\n",i+1);
    scanf_s("%d",&p->coef);
    printf("请输入第%d项指数\n",i+1);
    scanf_s("%d",&p->exp);
    L->next=p;
    p->next=NULL;
    L=L->next;
  }
  return head;
}
/*打印一元多项式*/
void printfPoly(ListPolynode L)
{
  ListPolynode p=L->next;
  while(p)
  {
    printf("%d*x^%d ",p->coef,p->exp);
    p=p->next;
  }
  printf("\n");
}
/*多项式相加*/
void addPoly(ListPolynode La,ListPolynode Lb)
{
  ListPolynode currenLa=La->next;//指向La的当前结点
  ListPolynode currenLb=Lb->next;//指向Lb的当前结点
  ListPolynode temp;//待释放空间的临时结点
  ListPolynode pre=La;/*位置指针，指向和多项式La,利用pre修改La*/
  int sum;//相同指数结点系数之和
  while (currenLa!=NULL&&currenLb!=NULL)
  {
    if (currenLa->exp<currenLb->exp)//La的当前结点指小于于Lb的当前结点指数
    {
      //Lb的当前位置不变,La当前位置后移
      pre->next=currenLa;
      pre=pre->next;
      currenLa=currenLa->next;
    } 
    else if (currenLa->exp==currenLb->exp)//La的当前结点指数等于Lb的当前结点指数
    {
      sum=currenLa->coef+currenLb->coef;
      if (sum!=0)
      {
        //将La当前结点的系数改为sum,并链接到pre；将La的当前结点后移，之后过河拆桥将La的当前结点释放
        currenLa->coef=sum;
        pre->next=currenLa;
        pre=pre->next;
        currenLa=currenLa->next;
        temp=currenLb;
        currenLb=currenLb->next;
        free(temp);
      } 
      else
      {
        temp=currenLa->next;
        free(currenLa);//过河拆桥干掉La当前结点
        currenLa=temp;
        temp=currenLb->next;
        free(currenLb);//策略雷同，过河拆桥
        currenLb=temp;
      }
    }
    else//La的当前结点指数大于Lb的当前结点指数
    {
      //Lb当前位置添加到La当前位置之前，同时Lb向后移动一位，La向后移动一位
      pre->next=currenLb;
      pre=pre->next;
      currenLb=currenLb->next;
    }
  }
  if (currenLa!=NULL)//La未结束，将其全部链接到pre
  {
    pre->next=currenLa;
  }
  else//若Lb未结束，将其全部链接到pre
  {
    pre->next=currenLb;
  }
}
int _tmain(int argc, _TCHAR* argv[])
{
  ListPolynode La=(ListPolynode)malloc(sizeof(node));
  La->next=NULL;
  printf("请输入创建一元多项式的项数\n");
  int n;
  scanf_s("%d",&n);
  createPoly1(La,n);
  printfPoly(La);
  ListPolynode Lb=(ListPolynode)malloc(sizeof(node));
  Lb->next=NULL;
  printf("请输入创建一元多项式的项数\n");
  scanf_s("%d",&n);
  createPoly(Lb,n);
  printfPoly(Lb);
  addPoly(La,Lb);
  printfPoly(La);
  system("pause");
  return 0;
}