题解 | #链表中环的入口结点#

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

        return null;
        
    }
}