反转链表

题目描述

实现

public class reverseLinkedList {

    public ListNode ReverseList(ListNode head) {
        if (head == null) {
            return null;
        }
        ListNode pre = null;
        ListNode now = head;
        while (now!= null) {
            //等号  左边指针，右边框
            //暂存
            ListNode nextNode = now.next;
            now.next = pre;
            //为下一次做准备
            pre = now;
            now = nextNode;
        }
        return pre;
    }
}