Leetcode 206: Reverse Linked List

问题描述

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL
Follow up:

A linked list can be reversed either iteratively or recursively. Could you implement both?

思路与实现

way1 迭代

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

来源：CSDN

作者：ying______

链接：https://blog.csdn.net/weixin_44135282/article/details/104186150