JAVA单链表反转

非递归的方法，直接代码：

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

public class ReverseLinkedNode {
    public static void main(String[] args) {
        Node node1 = new Node(1);
        Node node2 = new Node(4);
        Node node3 = new Node(2);
        Node node4 = new Node(0);
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        printAllNode(node1);
        Node newHead = reverseLinkedNode(node1);
        printAllNode(newHead);
    }
    public static void printAllNode(Node node){
        while(null != node){
            System.out.println(node.value);
            node = node.next;
        }
    }
    
    public static Node reverseLinkedNode(Node node){
        if(null == node || null == node.next){
            return node;
        }
        Node curNode = node.next;
        //注意头结点要更新为空
        node.next = null;
        Node nextNode = null;

        while(null != curNode){
            //暂存当前待处理节点的下一个，防止链条断了
            nextNode = curNode.next;
            //当前待处理节点指向当前的头结点
            curNode.next = node;
            //当前的头结点更新为上面的当前待处理节点
            node = curNode;
            //上面的当前待处理节点更新为上面暂存的下一个，如此循环到终点
            curNode = nextNode;
        }
        return node;
    }

}

递归时，遍历到最后一个节点，往前逐个更新链条即可

//递归方式
    public static Node reverseLinkedNodeOne(Node node) {
        if (null == node || null == node.next) {
            return node;
        } else {
            Node curNext = reverseLinkedNodeOne(node.next);
            node.next.next = node;
            node.next = null;
            return curNext;
        }

    }