题解 | #判断链表中是否有环#

import java.util.*;
/**
 * 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) {
        List<ListNode> list = new ArrayList<>();
        ListNode pNode = new ListNode(0);
        pNode.next = head;
        while(pNode.next != null) {
            pNode = pNode.next;
            if(list.contains(pNode)) {
                return true;
            }
            list.add(pNode);
        }
        return false;
    }
}