Descripción del Título
https://leetcode-cn.com/problems/linked-list-cycle/
Solución de dos puntas
/**
* 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) return false;
ListNode slow = head,fast = head;
while(fast!=null && fast.next!=null){
//一定要双指针,因为形成环不一定在head
slow = slow.next;
fast = fast.next.next;
if(slow == fast) return true;
}
return false;//没有回环
}
}