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) {
        HashSet<ListNode> nodes = new HashSet<>();
        int count = 0;
        ListNode pNode = pHead;
        while(pNode.next!=null){
            nodes.add(pNode);
            if (count == nodes.size()) {
                return pNode;
            }
            pNode = pNode.next;
            count++;
        }
        return null;
    }
}