多项式加法的链表实现

/*
 encoding:GBK
 time:
 environment:Dev-C++ 5.11 
*/
#include<iostream>
#include<math.h>
using namespace std;

#define maxn 200
bool sgn(float a){return fabs(a)<1e-8;}
typedef struct{//存放多项式的二元组,将二元组数组起别名 
    float coef;
    int exp;
}PolyArray[maxn];

struct PolyNode{//结点的定义 
    float coef;
    int exp ;
    PolyNode* next;
};

class Poly{//多项式类 
    private:
        PolyNode* Head;
    public:
        Poly();//构造函数
        ~Poly();//析构函数，释放多项式 
        void PolyDisplay();//显示多项式 
        void CreatePoly(PolyArray a,int n);//创建多项式链表
        void PolySort();//有序表排序
        void PolyAdd(Poly LB);//多项式相加 
};


void Poly::CreatePoly(PolyArray a,int n)//二元表以及二元表的大小 
{
    PolyNode *s,*r;
    int i;
    r = Head;
    for(int i = 0; i < n; i ++)    
    {
        s = new PolyNode;
        s->coef = a[i].coef;
        s->exp = a[i].exp;
        s->next = NULL;
        r->next = s;
        r = s;
    }
}
void Poly::PolySort()//表的排序 
{
    PolyNode *p,*q,*r;
    p = Head->next; 
    if(p!=NULL)
    {
        r = p->next;
        p->next = NULL;
        p = r;
        while(p!=NULL)
        {
            r = p->next;
            q = Head;
            while((q->next!=NULL) && (q->next->exp < p->exp))
                q = q->next;
                
                p->next = q->next;
                q->next = p;
                p = r;
        }
    }
}
//errors exist 
void Poly::PolyAdd(Poly LB)
{
    float sum;
    PolyNode *pa,*pb,*qa,*qb;
    pa = Head;//pa pb 指向两条链的头结点。qa qb 指向了两条链的首元 
    qa = pa->next;
    pb = LB.Head;
    qb = pb->next;
    while(qa!=NULL && qb!=NULL)//分成三种情况操作 
    {
        if(qa->exp < qb->exp)
        {
            pa = qa;
            qa = qa->next;
        }
        else if(qa->exp >qb->exp)
        {
            pb->next = qb->next;
            qb->next = qa;
            pa->next = qb;
            pa = qb;
            qb = pb->next;
        }
        else
        {
            sum = qa->coef+qb->coef;
            if(sum == 0)//系数为0的时候删除结点 ,浮点数不会严格等于零，所以需要判断 
            {
                pa->next = qa->next;
                delete qa;
                qa = qa->next;
                pb->next = qb->next;
                delete qb;
                qb = pb->next;
            }
            else
            {
                qa->coef = sum;
                pa = qa; qa = qa->next;
                pb->next = qb->next;
                delete qb;
                qb = pb->next;
            }
        }
    }
    if(qb!=NULL)
    {
        pa->next = qb;
    }
}
void Poly::PolyDisplay()
{
    PolyNode* q = Head;
    q = q->next;
    while(q!=NULL)
    {
        if(q->coef!=0)
        {
            cout<<"("<<q->coef<<","<<q->exp<<") "; 
        }
        q=q->next;    
    }
    cout<<endl; 
}
Poly::Poly(){Head = new PolyNode;}
Poly::~Poly(){Head = NULL;}
int main()
{
    Poly LA,LB;
    PolyArray a = {{7.0,0},{3.0,1},{9.0,8},{5.0,16}};
    PolyArray b = {{8.0,1},{22,7},{-9.0,8}};
    
//    PolyArray a1 = {{3.0,1},{7.0,0},{5.0,16},{9.0,8}};
    LA.CreatePoly(a,4);
    LB.CreatePoly(b,3);
    LA.PolyDisplay();
    LB.PolyDisplay();
    LA.PolySort();
    LB.PolySort();
    //展示合并之前的多项式 
    LA.PolyDisplay();
    LB.PolyDisplay();
    
    //多项式加法 
    LA.PolyAdd(LB);
    //展示合并后的多项式 
    LA.PolyDisplay(); 
}