链表实现一元函数相加

Question

链表相加函数出什么错了，代码一执行到那就结束了，不能输出最后相加的结果；
相加函数流程图：

正确的样例：

有问题的代码

#include<stdio.h>
#include<stdlib.h>
typedef struct PNODE
{
    float coef;
    int expn;
    struct PNODE*next;
}PNODE;
PNODE *insert(PNODE *head,PNODE *s);
PNODE *creatPoly(PNODE *head);
void  shuchu(PNODE *head);
PNODE *addPoly(PNODE *headA,PNODE *headB);
int main()
{
    PNODE *headA,*headB;
    headA=creatPoly(headA);
    printf("\n输出多项式A：\n");
    shuchu(headA);
    headB=creatPoly(headB);
    printf("\n输出多项式B：\n");
    shuchu(headB);
    headA=addPoly(headA,headB);
    printf("\n输出两个多项式相加后的结果多项式：\n");
    shuchu(headA);
    return 0;
}
PNODE *creatPoly(PNODE *head)
{
    int n,i;
    head=NULL;
    PNODE *s;
    printf("输入该多项式的项数：");
    scanf("%d",&n);
    printf("\n输入多项式各项系数以及指数：");
    for(i=1;i<=n;i++)
    {
        s=(PNODE*)malloc(sizeof(PNODE));
        s->next = NULL;
        scanf("%f %d",&s->coef,&s->expn);
        if(i!=1)
        {
            head=insert(head,s);
        }
        else
        {
            head=s;
            head->next=NULL;
        }
    }
    printf("输入完成\n");
    return head;
}
PNODE *insert(PNODE *head,PNODE *s)
{
    PNODE *p,*pr;
    p=pr=head;
    while(p->next && p->next->expn < s->expn)
    {
        p=p->next;
    }
    if (p == head && p->expn > s->expn){
        s->next = head;
        head = s;
    }
    else{
        s->next = p->next;
        p->next = s;
    }
    return head;
}
void shuchu(PNODE *head)
{
    PNODE *p;
    p=head;
    while(p!=NULL)
    {
        printf("\t%f %d,",p->coef,p->expn);
        p=p->next;
    }
    printf("\n");
}
PNODE *addPoly(PNODE *headA,PNODE *headB)
{
    PNODE *p1,*p2,*p3,*r; float sum=0;
    p1=headA,p2=headB;
    headA=NULL,p3=NULL;
    if(p1&&p2)
    {
        if(p1->expn==p2->expn)
        {
            sum=p1->coef+p2->coef;
            if(sum==0)
            {
               r=p1;
               p1=p1->next;
               free(r);
               r=p2;
               p2=p2->next;
               free(r);
            }
            else{
                p1->coef=sum;
                p3->next=p1;
                p3=p1;
                p1=p1=p1->next;
                r=p2;
                p2=p2->next;
                free(r);
            }
        }
        else{
           if(p1->expn<p2->expn){
               if(p3!=NULL){
                   p3->next=p1;
                   p3=p1;
                   p1=p1->next;
               }
               else{
                   p3=p1;
                   p1=p1->next;
                   p3->next=NULL;
               }
           }
           else{
               if(p3!=NULL){
                   p3->next=p2;
                   p3=p2;
                   p2=p2->next;
            }
            else{
                p3=p2;
                p2=p2->next;
                p3->next=NULL;
            }
           }

        }
    }
    else{
        if(p1!=NULL){
            p3->next=p1;
        }
        else{
            p3->next=p2;
        }
    }
    return p3;
}

Answer 1

修改如下，改动处见注释，供参考：

#include<stdio.h>
#include<stdlib.h>
typedef struct PNODE
{
    float coef;
    int expn;
    struct PNODE*next;
}PNODE;
PNODE *insert(PNODE *head,PNODE *s);
PNODE *creatPoly(PNODE *head);
void  shuchu(PNODE *head);
PNODE *addPoly(PNODE *headA,PNODE *headB);
int main()
{
    PNODE *headA,*headB;
    headA=creatPoly(headA);
    printf("\n输出多项式A：\n");
    shuchu(headA);
    headB=creatPoly(headB);
    printf("\n输出多项式B：\n");
    shuchu(headB);
    headA=addPoly(headA,headB);
    printf("\n输出两个多项式相加后的结果多项式：\n");
    shuchu(headA);
    
    return 0;
}
PNODE *creatPoly(PNODE *head)
{
    int n,i;
    head=NULL;
    PNODE *s;
    printf("输入该多项式的项数：");
    scanf("%d",&n);
    printf("\n输入多项式各项系数以及指数：");
    for(i=1;i<=n;i++)
    {
        s=(PNODE*)malloc(sizeof(PNODE));
        s->next = NULL;
        scanf("%f %d",&s->coef,&s->expn);
        if(i!=1)
        {
            head=insert(head,s);
        }
        else
        {
            head=s;
            head->next=NULL;
        }
    }
    printf("输入完成\n");
    return head;
}
PNODE *insert(PNODE *head,PNODE *s)
{
    PNODE *p,*pr;
    p=pr=head;
    while(p->next && p->next->expn < s->expn)
    {
        p=p->next;
    }
    if (p == head && p->expn > s->expn){
        s->next = head;
        head = s;
    }
    else{
        s->next = p->next;
        p->next = s;
    }
    return head;
}
void shuchu(PNODE *head)
{
    PNODE *p;
    p=head;
    while(p!=NULL)
    {
        printf("\t%f %d,",p->coef,p->expn);
        p=p->next;
    }
    printf("\n");
}
PNODE *addPoly(PNODE *headA,PNODE *headB)
{
    float sum=0;
    PNODE *p1,*p2,*p3,*r = NULL;  //修改
    p1=headA,p2=headB;
    headA=NULL,p3=NULL;
    while (p1 && p2)   //if(p1&&p2) 修改
    {
        if(p1->expn==p2->expn)
        {
            sum=p1->coef+p2->coef;
            if(sum==0)
            {
               r=p1;
               p1=p1->next;
               free(r);
               r=p2;
               p2=p2->next;
               free(r);
            }
            else{
                p1->coef=sum;
                if (!headA)  //修改
                    headA=p1;//修改
                else         //修改
                    p3->next=p1;
                p3 = p1;
                p1=p1->next;//p1=p1=p1->next;
                r=p2;
                p2=p2->next;
                free(r);
            }
        }
        else{
           if(p1->expn<p2->expn){
               if (!headA)      //修改
                   headA = p1;
               else             //修改
                   p3->next = p1;
               p3 = p1;
               p1=p1->next;
               p3->next=NULL;
               //if(p3!=NULL){ //修改
               //    p3->next=p1;
               //    p3=p1;
               //    p1=p1->next;
               //}
               //else{
               //    p3=p1;
               //    p1=p1->next;
               //    p3->next=NULL;
               //}
           }
           else{
               if (!headA)     //修改
                   headA = p2;
               else           //修改
                   p3->next = p2;
               p3 = p2;
               p2=p2->next;
               p3->next=NULL;
               //if(p3!=NULL){ //修改
               //    p3->next=p2;
               //    p3=p2;
               //    p2=p2->next;
               //}
               //else{
               //    p3=p2;
               //    p2=p2->next;
               //    p3->next=NULL;
               //}
           }

        }
    }
    p3->next = p1 ? p1 : p2; //修改
    return headA;            //修改
    //else{                 //修改
    //    if(p1!=NULL){
    //        p3->next=p1;
    //    }
    //    else{
    //        p3->next=p2;
    //    }
    //}
    //return p3;
}