剑指 Offer - 15：反转链表

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题目描述

输入一个链表，反转链表后，输出新链表的表头

题目链接：https://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca

解题思路

思路1：借助栈

思路2：递归

思路3：链表原地反转

public class Solution {
    public ListNode ReverseList(ListNode head) {
        if (head == null || head.next == null) return head;
        ListNode pre = null;
        ListNode next = null;
        while (head != null) {
            next = head.next;
            head.next = pre;
            pre = head;
            head = next;
        }
        return pre;
    }
}