[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;
}
}