在线等，C语言的链表答案

下面函数中链表head的节点以按num的值从小到大排序，且num没有重复值，函数功能是：在链表head中，插入stud结点，插入后新链表节点也按num的值从小到大排序，并返回新链表的表头。

struct student
{ long num;
float score;
struct student *next;
};

struct student * insert(struct student *head, struct student *stud)
{ [4] ;
struct student *p1;
struct student *p2;
p1 = head;
p0 = stud;
if(head == NULL)
{
head = p0;
p0->next = NULL;
}
else
{
while ( [5] && (p1->next != NULL))
{ p2 = p1;
p1 = p1->next;
}
if(p0->num <= p1->num)
{ if (p1 == head)
{head = p0;
p0->next = p1;
}
else {p2->next = p0;
[6] ;
}}
else
{ p1->next = p0;
p0->next = NULL;
} }
return [7] ;
}

struct student *p0;// [4] ;
(p0->num > p1->num)// [5] ;
p0->next = p1; //[6] ;
head; //[7] ;

struct student
{ long num;
float score;
struct student *next;
};

struct student * insert(struct student *head, struct student *stud)
{
struct student *p0;// [4] ;
struct student *p1;
struct student *p2;
p1 = head;
p0 = stud;
if(head == NULL)
{
head = p0;
p0->next = NULL;
}
else
{
while ( (p0->num > p1->num) && (p1->next != NULL)) //[5]
{
p2 = p1;
p1 = p1->next;
}
if(p0->num <= p1->num)
{
if (p1 == head)
{
head = p0;
p0->next = p1;
}
else