Given a node from a cyclic linked list which has been sorted, write a function to insert a value into the list such that it remains a cyclic sorted list. The given node can be any single node in the list. Return the inserted new node.

public class Solution {
    /** * @param node a list node in the list * @param x an integer * @return the inserted new list node */
    public ListNode insert(ListNode node, int x) {
        if (node == null) {
            node = new ListNode(x);
            node.next = node;
            return node;
        }
        ListNode point = node;
        ListNode prev = null;
        //循环一个周期
        do {
            prev = point;
            point = point.next;
            if (prev.val <= x && point.val >= x) {
                break;
            }
            if ((prev.val > point.val) && (x > prev.val || x < point.val)) {
                break;
            }
        } while (point != node);
        ListNode newNode = new ListNode(x);
        newNode.next = point;
        prev.next = newNode;
        return newNode;
    }
}