根据P257页例题13-8要求，编写一个链表结构，读取任意多个用户输入。之后删除学号为2017003的节点信息，并把删除后的链表打印出来

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>

typedef struct node_s {
    long num;
    float score;
    struct node_s* next;
} node_t;

int n;

node_t* create()
{
    node_t *head, *p1, *p2;
	
	n = 0;
    p1 = p2 = (node_t*) malloc(sizeof(node_t));
	scanf("%ld %f", &p1->num, &p1->score);
    head = NULL;

    while (p1->num != 0) {
        n++;
        if (n == 1)
            head = p1;
        else
            p2->next = p1;
        p2 = p1;
        p1 = (node_t*) malloc(sizeof(node_t));
        scanf("%ld %f", &p1->num, &p1->score);
    }
    p2->next = NULL;

    return (head);
}

void print(node_t *head)
{
    node_t *p;

    if (head == NULL) {
        return;
    }

    for (p = head; p != NULL; p = p->next) {
        printf("%ld %5.1f\n", p->num, p->score);
    }
}

node_t *find(node_t *head, int num)
{
    node_t *p;

    if (head == NULL) {
        return NULL;
    }

    for (p = head; p != NULL; p = p->next) {
        if(p->num == num){
            return p;
        }
    }

    return NULL;
}

node_t *del(node_t *head, int num)
{
    node_t *p1, *p2;

    if (head == NULL) {
		printf("list is NULL\n");
        return head;
    }

    for (p1 = head; p1->next != NULL; p2=p1, p1=p1->next) {
        if(num == p1->num){
            break;
        }
    }

    if (num == p1->num) {
        if (p1 == head) {
            head = p1->next;
        } else {
            p2->next = p1->next;
        }
        
		free(p1);   //书上漏了释放内存
        p1 = NULL;
        
		n--;

        return head;
    } else {
		printf("not exist: num %d\n", num);
        return head;
    }
}

node_t *insert(node_t *head, node_t *stud)
{
    node_t *p0, *p1, *p2;

    p1 = head;
    p0 = stud;

	//创建首节点
    if (head == NULL) {
        head = p0;
        p0->next = NULL;
        n++;
        return head;
    }

	//找到插入位置
    for (p1 = head; p1->next != NULL; p2=p1, p1 = p1->next) {
        if(p0->num < p1->num) {
            break;
        }
    }

    if (p0->num <= p1->num) { 
        if (p1 == head) {	//找到插入位置，插入队首
            head = p0;
			p0->next = p1;
        } else {	//找到插入位置，插入队列中间位置
            p2->next = p0;
            p0->next = p1;
        }
    } else {//找不到插入位置，插入队尾
        p1->next = p0;
        p0->next = NULL;
    }

    n++;

    return head;
}

//输出
void test_14_1(void)
{
    node_t* head;

    head = create();
    print(head);
}

//查找
void test_14_2(void)
{
    node_t* head;
    node_t* ret;

    head = create();
    ret = find(head, 2017003);
    if (ret) {
        printf("%ld %0.1f\n", ret->num, ret->score);
    } else {
        printf("%p\n", ret);
    }
}

//插入
node_t* test_14_3(void)
{
    node_t* head;
    node_t* stud;

    head = create();

    //插入头部
    stud = (node_t*) malloc(sizeof(node_t));
    stud->num = 2017000;
    stud->score = 85.0;
    head = insert(head, stud);

    //插入中间
    stud = (node_t*) malloc(sizeof(node_t));
    stud->num = 2017006;
    stud->score = 85.0;
    head = insert(head, stud);

    //插入尾部
    stud = (node_t*) malloc(sizeof(node_t));
    stud->num = 2017013;
    stud->score = 85.0;
    head = insert(head, stud);

    print(head);

	return head;
}

//删除
void test_14_4(void)
{
    node_t* head;

    head = create();
	head = del(head, 2017001);
	printf("delete num %d\n", 2017001);
	head = del(head, 2017005);
	printf("delete num %d\n", 2017005);
	head = del(head, 2017010);
	printf("delete num %d\n", 2017010);

    print(head);
}

//删除
void test_14_5(void)
{
    node_t* head;

    head = create();
	head = del(head, 2017003);
    print(head);
}


#define T5
/*
2017001 81.0
2017002 82.0
2017003 83.0
2017004 84.0
2017005 85.0
2017010 85.0
0 0
*/

int main(void)
{
#ifdef T1
    test_14_1();
#elif defined(T2)
    test_14_2();
#elif defined(T3)
    test_14_3();
#elif defined(T4)
    test_14_4();
#elif defined(T5)
    test_14_5();
#endif
	//system("pause");
}

输入

2017001 81.0
2017002 82.0
2017003 83.0
2017004 84.0
2017005 85.0
2017010 85.0
0 0

输出

2017001  81.0
2017002  82.0
2017004  84.0
2017005  85.0
2017010  85.0