题解 | #链表中环的入口结点#set集合和逐个删除都可以

import java.util.*;
/*
 public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}
*/
public class Solution {

    public ListNode EntryNodeOfLoop(ListNode pHead) {
        Set<ListNode> sl = new HashSet<>();
        while (pHead != null) {
            if(sl.contains(pHead)){
                return pHead;
            }
            sl.add(pHead);
            pHead = pHead.next;
        }
        return null;
    }
}