ARTS-6-算法练习-判断链表是否成环

public class LinkedListHasCycle {
     class ListNode {
          int val;
          ListNode next;
          ListNode(int x) {
              val = x;
              next = null;
          }
      }
    public boolean hasCycle(ListNode head) {
        ListNode slow=head;
        ListNode fast=head;
        while (fast!=null && fast.next!=null){
            slow=slow.next;
            fast=fast.next.next;
            if(slow==fast){
                return true;
            }
        }
        if(fast==null || fast.next==null){
            return false;
        }
        return false;
    }
}