输入链表数据（以数字-1作为输入结束的标志），例如建立链表1 2 3 则需输入1 2 3 -1;

好的，我可以回答这个问题。以下是一个示例代码，可以输入链表数据并创建链表：

#include <stdio.h>
#include <stdlib.h>

struct ListNode {
    int val;
    struct ListNode *next;
};

struct ListNode* createList() {
    struct ListNode *head = NULL;
    struct ListNode *tail = NULL;
    int num;
    while (1) {
        scanf("%d", &num);
        if (num == -1) {
            break;
        }
        struct ListNode *node = (struct ListNode*)malloc(sizeof(struct ListNode));
        node->val = num;
        node->next = NULL;
        if (head == NULL) {
            head = node;
            tail = node;
        } else {
            tail->next = node;
            tail = node;
        }
    }
    return head;
}

int main() {
    struct ListNode *head = createList();
    struct ListNode *p = head;
    while (p != NULL) {
        printf("%d ", p->val);
        p = p->next;
    }
    return 0;
}