链表-向有序环形单链表中插入节点

//向有序环形单链表中插入节点
public class Node{
    public int value;
    public Node next;
    public Node(int data){
        this.data=data;
    }
}
public Node insertNum(Node head,int num){
    Node node=new Node(num);
    if(head==null){
        node.next=node;
        return node
    }
    Node pre=head;
    Node cur=head;
    while(cur!=null){
        if(pre.value<=num&&cur.value>=num){
            break;
        }
        pre=cur;
        cur=cur.next;
    }
    pre.next=node;
    node.next=cur;
    return head.value<num?head:node;
}