//單鏈表的使用：快慢指標,如何判斷是否有環，環在哪個節點
    public static void main(String[] args) {
        Node<Integer> node1 = new Node(1,null);
        Node<Integer> node2 = new Node(2,null);
        Node<Integer> node3 = new Node(3,null);
        Node<Integer> node4 = new Node(4,null);
        Node
 
<Integer> node5 = new Node(5,null);
        Node<Integer> node6 = new Node(6,null);
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;
        node5.next = node6;
        node6.next = node4; //產生環

        Node quick = node1.next.next;
        Node low 
 
= node1.next;
        while (!quick.equals(low)){
            quick = quick.next.next;
            low = low.next;
        }
        System.out.println("有環,繼續找環");
        Node low2 = node1;
        while (!low2.equals(low)){
            low = low.next;
            low2 = low2.next;
        }
        System.out.println(
 
"環的節點值是：" + low2.t);
    }

    private static class Node<T>{
        private T t;
        private Node next;

        public Node(T t, Node next) {
            this.t = t;
            this.next = next;
        }
    }