数据结构一元多项式相加问题

#include <iostream>
using namespace std;
typedef struct node
{
    float coef;//系数域
    int exp;//指数域
    struct node *next;
}polynode;
//创建
polynode *init_polynode()
{
    int c = 0, e = 0;
    polynode *p = NULL, *q = NULL, *r = NULL;
    p = new polynode;
    r = p;
    r->next = NULL;                              //注意楼主没加(当只有一项时会出错)
    cout << "请按指数的升降次序输入系数和指数：" <<endl;
    cin >> c >> e;
    if(c == 0)
    {
        return NULL;
    }
    while (c != 0)
    {
        q = new polynode;
        q->coef = c;
        q->exp = e;
        q->next = NULL;
        r->next = q;
        r = q;
        cin >> c >> e;
    }
    if (r != NULL)
        r->next = NULL;
    return p;
}
void sort(polynode *L, int n)
{       //冒泡排序
    polynode *p, *q;
    if( L==NULL)               //当为空的时候,应该直接结束....
    {
        return;
    }
    p = L->next;
    q = p->next;
    int i, j, t, k;
    for (j = 0; i < n - 1; j++)
    {
        for (i = 0; i < n - j - 1; i++)
        {
            if (p->exp>q->exp)
            {
                t = p->exp;
                p->exp = q->exp;
                q->exp = t;
                k = p->coef;
                p->coef = q->coef;
                q->coef = k;
            }// if
            p = p->next;
            q = q->next;
        }// for
    }// for
}// PaixuF

//相加

///////////////////////////////////////////////////////////////////////
//
// 函数名       : *add_polynode
// 功能描述     : 多项式相加
// 参数         : polynode *pa
// 参数         : polynode *pb
// 返回值       : polynode
//
///////////////////////////////////////////////////////////////////////
polynode *add_polynode(polynode *pa, polynode *pb)
{
    polynode *head, *t, *s, *p1, *p2;
    int v;
   if( pa == NULL && pb == NULL)//  楼主应当加个判断，楼主多个地方忘了指针有空的时候。
       return NULL;
   else
       if(pa == NULL && pb != NULL)
           return pb;
       else
           if(pa != NULL && pb == NULL)
               return pa;

    p1 = pa->next;
    p2 = pb->next;
    t = pa;
    head = t;
    while (p1 && p2)
    {
        if (p1->exp == p2->exp)
        {
            v = p1->coef + p2->coef;
            if (v != 0)
            {
                p1->coef = v;
                t->next = p1;
                t = t->next;
                p1 = p1->next;
                s = p2;
                p2 = p2->next;
                delete s;
            }
            else
            {
                s = p1->next;
                delete p1;
                p1 = s;
                s = p2->next;
                delete p2;
                p2 = s;
            }
        }
        else if (p1->exp < p2->exp)
        {
            t->next = p1;
            t = t->next;
            p1 = p1->next;
        }
        else
        {
            t->next = p2;
            t = t->next;
            p2 = p2->next;
        }
    }
    if (p1)
        t->next = p1;
    else
        t->next = p2;
   
    return head;
}
void print_polynode(polynode *head)
{
    polynode *p = NULL;
    if( head == NULL)
        return ;
    p = head->next;
    if (p == NULL)
        cout << "多项式为NULL;"<<endl;
    else
    {
        while (p != NULL)
        {
            if (p->coef >= 0)
                cout <<p->coef << "X^ " <<p->exp << "+";
            else
                cout << p->coef << "X^" <<p->exp;
            p = p->next;
        }
        cout << endl;
    }
}

int main()
{
    polynode *heada = NULL, *headb = NULL, *headsum = NULL;
    int m, n;
    cout << "建立第一个函数：" <<endl;
    cout << "请输入多项式项数：";
    cin >> m;
    heada = init_polynode();
    cout << "第一个函数：" <<endl;
    sort(heada, m);
    print_polynode(heada);
    cout << "建立第二个函数：" <<endl;
    cout << "请输入多项式项数：";
    cin >> n;
    headb = init_polynode();
    cout << "第二个函数：" <<endl;
    sort(headb, n);
    print_polynode(headb);
    headsum = add_polynode(heada, headb);
    cout << "函数和为：" <<endl;
    print_polynode(headsum);
    return 0;
}
/*还有很多不完美的地方，比如明明已经输入了多项式几项却还要输入0 +其他任一整数，才能结束 。我没看全，楼主指的错误改了，0项也可以运行，望楼主其他地方应该加以改进，加油*/