一元多项式相加

/*********************                                          
title: 一元多项式相加
author: jay chang
date:   2009.4.12
********************

#include<stdlib.h>
#include<iostream>

using namespace std;

typedef struct poly{
  int coef;
  int exp;
  poly * next;
}poly,* Head; int count;

//创建一个一元多项式                                              
poly * createPoly()
{
  Head head=(poly*)malloc(sizeof(poly));
  int coef,exp;
  head->coef=-1;head->exp=-1;
  poly *p=head;
  cin>>coef;cin>>exp;
  while(coef!=-1&&exp!=-1)
  {
     poly *item=(poly*)malloc(sizeof(poly));
     item->coef=coef;
     item->exp=exp;
     cin>>coef;cin>>exp;
     p->next=item;
     p=p->next;
  }
  p->next=NULL;
  return head;
}

//将两个一元多项式相加
poly * addPoly(poly * ployA,poly * polyB)
{
  count=1;
  Head head=(poly *)malloc(sizeof(poly));
  poly * pos=head,*temp;
  pos->coef=-1;pos->exp=-1;
  poly * pA= ployA->next;
  poly * pB= polyB->next;
  while(pA!=NULL&&pB!=NULL)
  {
     if(pA->exp<pB->exp){
        pos->next=pA;
        pA=pA->next;
        pos=pos->next;
     }
     else if(pA->exp>pB->exp){
        pos->next=pB;
        pB=pB->next;
        pos=pos->next;
      }
      else if(pA->exp==pB->exp){
          int sum=pA->coef+pB->coef;
          if(sum==0){
             pA=pA->next;
             pB=pB->next;
          }
          else{
             pA->coef=sum;
             pos->next=pA;
             pos=pos->next;
             pA=pA->next;
             pB=pB->next;
          }
   
       }
      count++;//一元二次方程的长度计数器
  }
  while(pA!=NULL)//如果pA多项式还有项
  {
     pos->next=pA;
     pos=pos->next;
     pA=pA->next;
     count++;
  }
  while(pB!=NULL)//如果pB 多项式还有项
  {
     pos->next=pB;
     pos=pos->next;
     pB=pB->next;
     count++;
  }
  return head;
}

//打印一元多项式
void procOutput(Head head)
{
  poly * p=head->next;
  int length=1;
  cout<<"f(x)=";
  while(p!=NULL){
     //cout<<length<<" "<<count<<"\n";
     if(length==5)
     { //如果是最后一个元素
        if(p->exp==0)
           cout<<p->coef<<"\n";
        else
           cout<<p->coef<<"*x^"<<p->exp<<"\n";
      }
      else if(length!=count)
      {               //不是最后一个元素
         if(p->coef==0)
            cout<<p->coef<<"+";
        else
            cout<<p->coef<<"*x^"<<p->exp<<"+";
       }
       p=p->next;length++;
  }  
}

int main()
{
   poly * polyA,* polyB;
   polyA=createPoly();
   polyB=createPoly();
   Head head=addPoly(polyA,polyB);
   procOutput(polyA);
   return 0;
}

/*
使用方法:
例如要输入f(x)=3*x+4*x+7*x^3+6*x^4;
    g(x)=7*x+8*x^4+9*x^6;
则只要输入
   3 0
   4 1
   7 3
   6 4
   -1 -1 （表示一个多项式输入结束）
   7 1
   8 4
   9 6
   -1 -1
*/