思路

解法1：适用于数字不多的

1.把节点的数，都放进一个arraylist中

2.调用Collections.reverse(list)方法，将list转置

3.再遍历list，逐个放入数字

代码

解法1

import java.util.ArrayList;
import java.util.Collections;

public class Main {
    public static void main(String[] args) {

    }

       public static class ListNode {
           int val;
           ListNode next;
           ListNode() {}
           ListNode(int val) { this.val = val; }
           ListNode(int val, ListNode next) { this.val = val; this.next = next; }
       }

        static class  Solution {
        public ListNode reverseList(ListNode head) {
            ListNode cur = head;
            ArrayList<Integer> list = new ArrayList<>();
            while (cur != null) {
                list.add(cur.val);
                cur=cur.next;
            }
            Collections.reverse(list);
            cur=head;
            for (int i = 0; i <= list.size() - 1; i++) {
                cur.val=list.get(i);
                cur=cur.next;
            }
            return head;

        }
}

记录

总结