题目链接

206. 反转链表

思路

先添加一个头结点real_head。再设置real_head.next = null，通过不断运用头插法将p所指的结点插入到real_head.next，完成反转操作。

代码

class Solution {
    public ListNode reverseList(ListNode head) {

        ListNode real_head = new ListNode(0, head);
        ListNode p = real_head.next;
        real_head.next = null;

        while (p != null){
            ListNode q = p.next;
            p.next = real_head.next;
            real_head.next = p;
            p = q;
        }

        return real_head.next;
    }
}