设有a,b两个链表，每个链表中的节点包括学号·成绩。要求将两个链表合并为一个链表，按学号升序排列
struct student *insert(struct student *ah,struct student *bh)  
{struct student  *pa1 , *pa2,*pb1,*pb2;  
 pa2=pa1=ah;  
 pb2=pb1=bh;  
 do   
 {while((pb1->num>pa1->num)&&(pa1->next!=NULL))  
{pa2=pa1;  
pa1=pa1->next;  
}  
if(pb->num<=pa1->num)&nbsp;&nbsp;
{if(ah=pa1)&nbsp;&nbsp;
&nbsp;ah=pb1;&nbsp;&nbsp;
&nbsp;else&nbsp;pa2->next=pb1;&nbsp;&nbsp;
&nbsp;pb1=pb1->next;&nbsp;&nbsp;
&nbsp;pb2->next=pa1;&nbsp;&nbsp;
pa2=pb2;&nbsp;&nbsp;
pb2=pb1;&nbsp;&nbsp;
}&nbsp;&nbsp;
}&nbsp;&nbsp;

谁给我讲讲思路 万分感谢

struct student *insert(struct student *ah,struct student *bh)
{struct student *pa1,*pa2,*pb1,*pb2;
pa2=pa1=ah;
pb2=pb1=bh;
do
{while((pb1->num>pa1->num)&&(pa1->next!=NULL))
{pa2=pa1;
pa1=pa1->next;
}
if(pb1->num<=pa1->num)
{if(ah==pa1)
ah=pb1;
else pa2->next=pb1;
pb1=pb1->next;
pb2->next=pa1;
pa2=pb2;
pb2=pb1;
}
}
while((pa1->next!=NULL&&pb1!=NULL));
if(pb1!=NULL)
pa1->next=pb1;
return(ah);
}     额  不好意思  弄错了  是这个