/
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode next;
* };
/

struct ListNode reverseList(struct ListNode head)
{
struct ListNode prev = NULL;
struct ListNode curr = head;
struct ListNode *next = NULL;

while (curr != NULL) {
    next = curr->next; // 先保存下一个节点
    curr->next = prev; // 将当前节点的next指向prev
    prev = curr;       // 移动prev和curr
    curr = next;
}

return prev; // 返回新的头结点

}