[数据结构与算法]Leetcode-206.反转链表（JAVA）

给你单链表的头节点?head?，请你反转链表，并返回反转后的链表。

输入：head = [1,2,3,4,5]
输出：[5,4,3,2,1]

输入：head = []
输出：[]

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/reverse-linked-list/

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */

class Solution 
{
    public ListNode reverseList(ListNode head) 
    {
        ListNode prior = null; 
        ListNode cur = head; 

        while (cur != null)             //同时解决链表为空的情况
        {
            ListNode temp = cur.next;   //暂存下个结点的值为之后cur指针赋值
            cur.next = prior;           //next指向之前的节点，即反转
            prior = cur;                //先前指针后移
            cur = temp;                 //当前指针后移
        }
        return prior;
    }
}