/* public class ListNode {    int val;    ListNode next = null;    ListNode(int val) {        this.val = val;    }}*/public class Solution {    public static ListNode EntryNodeOfLoop(ListNode pHead)    {        ListNode meet = meetNode(pHead);                if(meet == null){            return null;        }                int repeatNode = 1;        ListNode node = meet;        while(node.next != meet){            ++repeatNode;            node = node.next;        }        node = pHead;        //将快节点放在比头结点多环数个节点的位置        for(int i = 0; i < repeatNode; i++){            node = node.next;        }        ListNode node2 = pHead;        while(node != node2){            node = node.next;            node2 = node2.next;        }        return node;            }    public static ListNode meetNode(ListNode pHead){                 if(pHead == null || pHead.next == null){            return null;        }        ListNode pSlow = pHead.next;        ListNode pFast = pSlow.next;                while(pSlow != null && pFast !=null){            if(pSlow == pFast){                return pFast;            }            pSlow = pSlow.next;            pFast = pFast.next;            if(pFast != null){                pFast = pFast.next;            }        }        return null;    }}