怎么修改这个链表的插入 使输出可以从小到大输出

Question

怎么修改这个链表的插入 使输出可以从小到大输出
错误的

#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);
    shuchu(headA);
    headB=creatPoly(headB);
    shuchu(headB);
}
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));
        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->expn<s->expn&&p->next!=NULL)
    {
        pr=p;
        p=p->next;
    }
    if(p->expn>=s->expn&&p->next!=NULL)
    {
        if(p==head)
        {
            head=s;
            s->next=p;
        }
        else
        {
            pr->next=s;
            s->next=p;
        }
    }
    else
    {
        p->next=s;
        s->next=NULL;
    }
    return head;
}
void shuchu(PNODE *head)
{
    PNODE *p;
    p=head;
    printf("\n输出多项式：\n");
    while(p!=NULL)
    {
        printf("\t%f %d,",p->coef,p->expn);
        p=p->next;
    }
}

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);
    shuchu(headA);
    headB=creatPoly(headB);
    shuchu(headB);
    
    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;                 //修改
        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->expn<s->expn&&p->next!=NULL)  //修改
    {
        //pr=p; //修改
        p=p->next;
    }
    if (p == head && p->expn > s->expn){//修改
        s->next = head;
        head = s;
    }
    else{                               //修改
        s->next = p->next;
        p->next = s;
    }
    //if(p->expn>=s->expn&&p->next!=NULL)//修改 以下删除
    //{
    //    if(p==head)
    //   {
    //        head=s;
    //        s->next=p;
    //    }
    //    else
    //    {
    //        pr->next=s;
    //        s->next=p;
    //    }
    //}
    //else
    //{
    //    p->next=s;
    //    s->next=NULL;
    //}
    return head;
}
void shuchu(PNODE *head)
{
    PNODE *p;
    p=head;
    printf("\n输出多项式：\n");
    while(p!=NULL)
    {
        printf("\t%f %d,",p->coef,p->expn);
        p=p->next;
    }
    printf("\n");    //修改
}