剑指Offer-Java-反转链表

package com.hlq.test;
/**
 * @author helongqiang
 * @date 2020/5/17 12:38
 */
/**
 * 输入一个链表，反转链表后，输出新链表的表头。
 */
public class Solution {
    public ListNode ReverseList(ListNode head){
        if(head == null){
            return null;
        }
        ListNode pre = null;
        ListNode nex = null;
        while(head.next != null){
            nex = head.next;
            head.next = pre;
            pre = head;
            head = nex;
        }
        head.next = pre;
        return head;
    }
}