JAVA-Linked List Cycle I&&Linked List Cycle II

public class Solution {
    public ListNode detectCycle(ListNode head) {
        if(head==null||head.next==null) return null;
        ListNode slow=head;
        ListNode fast=head;
        int count=0;
        while(fast.next!=null&&fast.next.next!=null){
            slow=slow.next;
            fast=fast.next.next;
            count++;
            if(slow==fast)  break;
        }
        if(slow==fast&&count!=0){
            ListNode res=head;
            while(res!=slow){
                res=res.next;
                slow=slow.next;
            }
            return res;
        }else{
            return null;
        }
    }
}