链表逆序，java实现

package com.cskaoyan.linkedlist;
//反转数组
public class LinkedListDemo2 {
    public static Node reverse(Node head){
        //若输入head是null 或者这个链表只有一个元素,不需要反转
        //null -->null
        //a,null-->a,null
        if(head==null||head.next==null) return head ;
        Node prev=null;
        Node curr=head;
        while(curr!=null){
            Node nextNode=curr.next;
            curr.next=prev;
            prev=curr;
            curr=nextNode;
        }
        return prev;
    }
    //使用递归使链表逆序
    public static Node reverse1(Node head){
        if (head == null || head.next == null) return head;
        Node node=reverse1(head.next);
        head.next.next=head;
        head.next = null;
        return node;
    }
    public static void main(String[] args) {
        Node node = new Node(3);
        node = new Node(2, node);
        node = new Node(1, node);
        Node head = reverse(node);
        System.out.print(head.val + " ");
    }
}

package com.cskaoyan.linkedlist;

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