[LeetCode]206. Reverse Linked List

https://leetcode.com/problems/reverse-linked-list/

反转链表

最基本的题目，要熟练，很多地方会用到。

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode reverseList(ListNode head) {        ListNode pre = null;        while (head != null) {            ListNode next = head.next;            head.next = pre;            pre = head;            head = next;        }        return pre;    }}