编译成功了，但是输出有问题，为什么啊

Question

#include <stdio.h>
#include <stdlib.h>
struct ListNode {
int data;
struct ListNode *next;
};
void printlist( struct ListNode *L ){
struct ListNode *p = L;
while (p) {
printf("%d ", p->data);
p = p->next;
}
printf("\n");
}
struct ListNode *readlist(int n){
struct ListNode *head,*p,*last;
int i;
head=(struct ListNode *)malloc(sizeof(struct ListNode));
head->next=NULL;
last=head;
for(i=1;i<=n;i++){
p=(struct ListNode *)malloc(sizeof(struct ListNode));
scanf("%d",&p->data);
p->next=NULL;
last->next=p;
last=p; }
return head;
}
struct ListNode *deletem( struct ListNode *L, int k ){
struct ListNode *p,*pre;
p=L;
pre=NULL;
while(p) {
if(p->data==k) {
if(pre)
pre->next=p->next;
else
L=p->next; }
else pre=p;
p=p->next; }
free(p);
return L;}
int main(){
int n;
int k;
scanf("%d", &n);
scanf("%d", &k);
struct ListNode *head;
head=readlist(n);
struct ListNode *L;
L= deletem(L, k);
printlist(L);
return 0;}

Answer 1

链表有头节点, 第一个数据节点是L->next

p = L;
改成
p = L->next;

L = deletem(L, k); //deletem 中 L 改成 head
L = deletem(head, k);

你题目的解答代码如下：

#include <stdio.h>
#include <stdlib.h>
struct ListNode
{
    int data;
    struct ListNode *next;
};
void printlist(struct ListNode *L)
{
    struct ListNode *p = L->next;  //链表有头节点, 第一个数据节点是L->next
    while (p)
    {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("\n");
}
struct ListNode *readlist(int n)
{
    struct ListNode *head, *p, *last;
    int i;
    head = (struct ListNode *)malloc(sizeof(struct ListNode));
    head->next = NULL;
    last = head;
    for (i = 1; i <= n; i++)
    {
        p = (struct ListNode *)malloc(sizeof(struct ListNode));
        scanf("%d", &p->data);
        p->next = NULL;
        last->next = p;
        last = p;
    }
    return head;
}
struct ListNode *deletem(struct ListNode *L, int k)
{
    struct ListNode *p, *pre;
    p = L->next;  //链表有头节点, 第一个数据节点是L->next
    pre = L;
    while (p)
    {
        if (p->data == k)
        {
            pre->next = p->next;
            break;
        }
        else
            pre = p;
        p = p->next;
    }
    free(p);
    return L;
}
int main()
{
    int n;
    int k;
    scanf("%d", &n);
    scanf("%d", &k);
    struct ListNode *head;
    head = readlist(n);
    struct ListNode *L;
    L = deletem(head, k); //deletem 中 L 改成 head
    printlist(L);
    return 0;
}

如果要链表无头节点, 改成

#include <stdio.h>
#include <stdlib.h>
struct ListNode
{
    int data;
    struct ListNode *next;
};
void printlist(struct ListNode *L)
{
    struct ListNode *p = L;
    while (p)
    {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("\n");
}
struct ListNode *readlist(int n)
{
    //如果要链表无头节点, 改成
    struct ListNode *head, *p, *last;
    int i;
    last = NULL;
    for (i = 1; i <= n; i++)
    {
        p = (struct ListNode *)malloc(sizeof(struct ListNode));
        scanf("%d", &p->data);
        p->next = NULL;
        if (last)
            last->next = p;
        else
            head = p;
        last = p;
    }
    return head;
}
struct ListNode *deletem(struct ListNode *L, int k)
{
    struct ListNode *p, *pre;
    p = L;
    pre = NULL;
    while (p)
    {
        if (p->data == k)
        {
            if (pre)
                pre->next = p->next;
            else
                L = p->next;
            break;
        }
        else
            pre = p;
        p = p->next;
    }
    free(p);
    return L;
}
int main()
{
    int n;
    int k;
    scanf("%d", &n);
    scanf("%d", &k);
    struct ListNode *head;
    head = readlist(n);
    struct ListNode *L;
    L = deletem(head, k); //deletem 中 L 改成 head
    printlist(L);
    return 0;
}

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