/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
/*
  - 将链表中的值放进数组，然后使用双指针
  - 都是基础操作，没什么好说的
*/
bool isPalindrome(struct ListNode* head) {
    int vals[100001], vals_num = 0;
    while (head != NULL) {
        vals[vals_num++] = head->val;
        head = head->next;
    }
    for (int i = 0, j = vals_num - 1; i < j; ++i, --j) {
        if (vals[i] != vals[j]) {
            return false;
        }
    }
    return true;
}