Java
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public boolean hasCycle(ListNode head) {
if(head==null) return false;
ListNode fast=head;
ListNode slow=head;
while(fast!=null&&fast.next!=null)
{
if(fast.next.next==null) return false;
fast=fast.next.next;
slow=slow.next;
if(fast==slow)
return true;
}
return false;
}
}
