题解 | #判断链表中是否有环#
判断链表中是否有环
http://www.nowcoder.com/practice/650474f313294468a4ded3ce0f7898b9
/**
* 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||head.next==null||head.next.next==null)
{
return false;
}
ListNode head1 = head.next;
ListNode head2 = head.next.next;
while(true){
if(head2.next==null||head2.next.next==null)
{
return false;
}
if(head2==head1)
{
return true;
}
head1 = head1.next;
head2 = head2.next.next;
}
}
} 
