进来看看吧，标题怎么这么难

Question

本题要求实现两个函数，一个将输入的学生成绩组织成单向链表；另一个将成绩低于某分数线的学生结点从链表中删除。

struct stud_node *createlist();
struct stud_node *deletelist( struct stud_node *head, int min_score );

函数createlist利用scanf从输入中获取学生的信息，将其组织成单向链表，并返回链表头指针。链表节点结构定义如下：

struct stud_node {
    int              num;      /*学号*/
    char             name[20]; /*姓名*/
    int              score;    /*成绩*/
    struct stud_node *next;    /*指向下个结点的指针*/
};

输入为若干个学生的信息（学号、姓名、成绩），当输入学号为0时结束。

函数deletelist从以head为头指针的链表中删除成绩低于min_score的学生，并返回结果链表的头指针。

struct stud_node *createlist()
{
    struct stud_node *pMove=NULL,*head=NULL,*tail=NULL;
    pMove=(struct stud_node*)malloc(sizeof(struct stud_node));
    scanf("%d",&pMove->num);
    while(pMove->num!=0)
    {
        scanf("%s %d",pMove->name,&pMove->score);
        if(head==NULL){
           head=pMove; 
        }
        else{
            tail->next=pMove;
        }
        tail=pMove;
        pMove=(struct stud_node*)malloc(sizeof(struct stud_node));
    }
    return head;
}
struct stud_node *deletelist( struct stud_node *head, int min_score )
{
    struct stud_node* p=head;
    if(!head)
        return NULL;
    p=(struct stud_node*)malloc(sizeof(struct stud_node));
    while(p->next)
    {
        if(p->score<min_score)
        {
            struct stud_node* temp=p;
            p=temp->next;
            free(temp);
        }
        else
        {
            p=p->next;
        }
    }
    return head;
}

为什么我这个代码是错的QAQ，有没有好心的给个意见！

Answer 1

修改如下，供参考：

#include <stdio.h>
#include <stdlib.h>
struct stud_node {
    int              num;      //学号
    char             name[20]; //姓名
    int              score;    //成绩
    struct stud_node* next;    //指向下个结点的指针
};
struct stud_node* createlist()
{
    struct stud_node* pMove = NULL, * head = NULL, * tail = NULL;
    while (1)       //while (pMove->num != 0)//修改
    {
        pMove = (struct stud_node*)malloc(sizeof(struct stud_node));
        pMove->next = NULL;                   //修改
        scanf("%d", &pMove->num);
        if (pMove->num == 0) {               //修改 
            free(pMove);
            break;                           //修改
        }
        scanf("%s %d", pMove->name, &pMove->score);
        if (head == NULL) {
            head = pMove;
        }
        else {
            tail->next = pMove;
        }
        tail = pMove;
        //pMove = (struct stud_node*)malloc(sizeof(struct stud_node)); //修改
    }
    return head;
}
struct stud_node* deletelist(struct stud_node* head, int min_score)
{
    struct stud_node* p = head, * pre = NULL;  //修改
    if (!head)
        return NULL;
    //p = (struct stud_node*)malloc(sizeof(struct stud_node)); //修改
    while (p)   //while (p->next)
    {
        if (p->score < min_score)
        {
            if (p == head) {     //修改
                head = p->next;  //修改
                free(p);        //修改
                p = head;       //修改 
            }
            else {
                pre->next = p->next; //修改
                free(p);            //修改 
                p = pre;            //修改
            }
        }
        else{
            pre = p;           //修改
            p = p->next;
        }
    }
    return head;
}
void print(stud_node* L)
{
    stud_node* p = L;
    while (p) {
        printf("%d %s %d\n", p->num, p->name, p->score);
        p = p->next;
    }
}
int main()
{
    struct stud_node* L;
    L = createlist();
    L = deletelist(L, 100);
    print(L);
    return 0;
}