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) {
        if(pHead.next==null) return null;
        Map<Integer,Integer> map=new HashMap<>();
        ListNode 
                 temp=pHead;
        int i=1,j=0;
        while(temp.next!=null){
            map.put(temp.val,i);
            temp=temp.next;
            i++;
            if(map.containsKey(temp.val))
               
                return temp;
        }
        return null;
    }
}