LeetCode 206 Reverse Linked List 反转链表 Java

举例1：

输入： [1,2,3,4,5]，

输出： [5,4,3,2,1].

举例2：

输入： []

输出：[]

思路：方法有三种，分别是递归，栈，双指针，本篇使用栈，原理为利用栈的后进先出特性，将链表节点依次压入栈中，紧接着将其依次弹出栈，以用来构建新的反转链表

/*** Definition for singly-linked list.* public class ListNode {* int val;* ListNode next;* ListNode() {}* ListNode(int val) { this.val = val; }* ListNode(int val, ListNode next) { this.val = val; this.next = next; }* }*/
class Solution {public ListNode reverseList(ListNode head) {if (head == null) {return null;}//将链表节点依次压入栈中Stack<ListNode> nodeStack = new Stack<>();while (head != null) {nodeStack.push(head);head = head.next;}//依次弹出栈，构建新的反转链表ListNode reverseList = nodeStack.pop();ListNode currect = reverseList;while (!nodeStack.isEmpty()) {currect.next = nodeStack.pop();currect = currect.next;}currect.next = null;return reverseList;}
}