题解 | #反转链表#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
struct ListNode* ReverseList(struct ListNode* head ) {
    if(head == NULL)
    return NULL;
    if(head->next == NULL)
    return head;
    struct ListNode *pre = NULL;
    struct ListNode *nex= NULL;
    struct ListNode *H = head;
    while (H) {
        nex = H->next;
        H->next = pre;
        pre = H;
        H = nex;
    }
    return pre;
}