#include <stdio.h>
#include <stdlib.h>
typedef struct polynode
{      char name[6];
       int num;
       int score;
       struct polynode *next;
}      PNode;
PNode *Creat_Linklist(int n);
PNode *sort_num(PNode *head);
void print_Linklist(PNode *head);


int main()
{   
    PNode *p;
    int n;    
    printf("请输入学生的人数：\n");
    scanf("%d",&n);
    p=Creat_Linklist(n);
    p=sort_num(p);
    print_Linklist(p);
    return 0;
}



PNode *Creat_Linklist(int n)
{    
    PNode *head,*p,*q;
     int i;
     head=(PNode *)malloc(sizeof(PNode));
     head->next=NULL;
     p=head;
     printf("请输入学生的信息：\n");
     for(i=1;i<=n;i++)
     {q=(PNode *)malloc(sizeof(PNode));
      printf("姓名：");
      scanf("%s",&q->name);
      printf("学号：");
      scanf("%d",&q->num);
      printf("成绩：");
      scanf("%d",&q->score);
      q->next=NULL;
      p->next=q;
      p=q;
     }
     return(head);
}


void print_Linklist(PNode *head)
{     PNode *p;
      p=head->next;
      printf("姓名   学号  成绩\n ");
      while(p)
      {printf("%-5s%5d%5d\n",p->name,p->num,p->score);
      p=p->next;
      }

}


PNode *sort_num(PNode *head)
{     PNode *p,*pre,*pt,*head1;
      int inum;
      p=head->next;
      head1=(PNode *)malloc(sizeof(PNode));
      head1->next=NULL;
      pt=head1;
      while(p)
      {inum=p->num;
      if(p->next=NULL) {pt->next=p; p->next=NULL;}
        else
         {if(inum<p->next->num) {inum=p->next->num;pre=p;}
         p=p->next;
         }
        if(pre->next=NULL) {pt->next=pre;pt=pre;pt->next=NULL;}
        else if(pre->next->next=NULL){p=pre->next;pre->next=NULL;pt->next=p;pt=p;pt->next=NULL;}
        p=pre->next;
         pre->next=p->next;
         pt->next=p;
         pt=p;
         p->next=NULL;
         p=head->next;
         

      }
      pt->next=p;
      pt=p;
      pt->next=NULL;
      return(head1);
}

运行没错误,但没结果,该怎么改?
PNode *sort_num(PNode *head)函数 有点问题